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The Mymaridae are the smallest insects. This video explains their numerous adaptations to being as small as 140 microns yet still complex, such as smaller cells with as little cytoplasm as possible, denucleated neurons, loss of several body parts (including eyes and hearts, depending on the species), and parasitism as an alternative to insects' usual level of nutrition in eggs. My question is why natural selection would favour their being so small in the first place.
Since few extant species have been extensively observed, this question may require some "just so story" speculation, hopefully informed by other examples of organisms becoming unusually, almost prohibitively small for their taxa. On the other hand, their fossil record covers about 100 million years, so perhaps the time and place of shrinking intermediates would suggest specific explanations.
Fairy flies can be so small because they mooch off other insects' eggs, this is one of the reasons why they need to be small, then after that, they don't need to eat as they will die in only a few days. Information can be found on the "how do they manage to be so small" section of this PDF: https://www.cell.com/current-biology/pdf/S0960-9822(18)31343-5.pdf
New 'Fairy' Insect Is Mind-Blowingly Small
A new species of tiny fly named after the fairy in "Peter Pan" is mind-blowingly miniscule, with delicate wings trimmed in fringe.
Tinkerbella nana is a newly discovered species of fairyfly from Costa Rica. Fairyflies are a type of chalcid wasp, and almost all are parasites, living on the eggs and larvae of other insects. It's a gruesome way to live, but it makes fairyflies useful for farmers, who sometimes import them to control nasty pests.
Many fairyflies are extraordinarily tiny, including Kikiki huna, a Hawaiian species that grows to be only 0.005 inches (0.13 millimeters) long &mdash about the diameter of the tip of a fine drawing pen. This makes them tough to find, but researchers led by John Huber of Natural Resources Canada conducted their search by seeking out insect eggs in leaf litter, soil and on plants in the Costa Rican province of Alajeula.
There, they found specimens of T. nana, none of which were more than 250 micrometers in length. One micrometer is a thousandth of a millimeter.
Under the microscope, these teeny-tiny insects reveal fine detail, particularly their long, skinny wings, which terminate in hairlike fringe. This wing shape may help ultra-small insects reduce turbulence and drag when they fly, a feat that requires beating their wings hundreds of times per second.
Researchers don't know how small insects can get, Huber said.
"If we have not already found them, we must surely be close to discovering the smallest insects," he said in a statement. The researchers published their discovery today (April 24) in the Journal of Hymenoptera Research.
As an analytical biochemistry assay and a "wet lab" technique, ELISA involves detection of an analyte (i.e., the specific substance whose presence is being quantitatively or qualitatively analyzed) in a liquid sample by a method that continues to use liquid reagents during the analysis (i.e., controlled sequence of biochemical reactions that will generate a signal which can be easily quantified and interpreted as a measure of the amount of analyte in the sample) that stays liquid and remains inside a reaction chamber or well needed to keep the reactants contained.   This is in contrast to "dry lab" techniques that use dry strips. Even if the sample is liquid (e.g., a measured small drop), the final detection step in "dry" analysis involves reading of a dried strip by methods such as reflectometry and does not need a reaction containment chamber to prevent spillover or mixing between samples. 
As a heterogenous assay, ELISA separates some component of the analytical reaction mixture by adsorbing certain components onto a solid phase which is physically immobilized. In ELISA, a liquid sample is added onto a stationary solid phase with special binding properties and is followed by multiple liquid reagents that are sequentially added, incubated, and washed, followed by some optical change (e.g., color development by the product of an enzymatic reaction) in the final liquid in the well from which the quantity of the analyte is measured. The quantitative "reading" is usually based on detection of intensity of transmitted light by spectrophotometry, which involves quantitation of transmission of some specific wavelength of light through the liquid (as well as the transparent bottom of the well in the multiple-well plate format).   The sensitivity of detection depends on amplification of the signal during the analytic reactions. Since enzyme reactions are very well known amplification processes, the signal is generated by enzymes which are linked to the detection reagents in fixed proportions to allow accurate quantification, and thus the name "enzyme-linked." 
The analyte is also called the ligand because it will specifically bind or ligate to a detection reagent, thus ELISA falls under the bigger category of ligand binding assays.  The ligand-specific binding reagent is "immobilized," i.e., usually coated and dried onto the transparent bottom and sometimes also side wall of a well  (the stationary "solid phase"/"solid substrate" here as opposed to solid microparticle/beads that can be washed away), which is usually constructed as a multiple-well plate known as the "ELISA plate." Conventionally, like other forms of immunoassays, the specificity of antigen-antibody type reaction is used because it is easy to raise an antibody specifically against an antigen in bulk as a reagent. Alternatively, if the analyte itself is an antibody, its target antigen can be used as the binding reagent. 
Before the development of the ELISA, the only option for conducting an immunoassay was radioimmunoassay, a technique using radioactively labeled antigens or antibodies. In radioimmunoassay, the radioactivity provides the signal, which indicates whether a specific antigen or antibody is present in the sample. Radioimmunoassay was first described in a scientific paper by Rosalyn Sussman Yalow and Solomon Berson published in 1960. 
As radioactivity poses a potential health threat, a safer alternative was sought. A suitable alternative to radioimmunoassay would substitute a nonradioactive signal in place of the radioactive signal. When enzymes (such as horseradish peroxidase) react with appropriate substrates (such as ABTS or TMB), a change in color occurs, which is used as a signal. However, the signal has to be associated with the presence of antibody or antigen, which is why the enzyme has to be linked to an appropriate antibody. This linking process was independently developed by Stratis Avrameas and G. B. Pierce.  Since it is necessary to remove any unbound antibody or antigen by washing, the antibody or antigen has to be fixed to the surface of the container i.e., the immunosorbent must be prepared. A technique to accomplish this was published by Wide and Jerker Porath in 1966. 
In 1971, Peter Perlmann and Eva Engvall at Stockholm University in Sweden, and Anton Schuurs and Bauke van Weemen in the Netherlands independently published papers that synthesized this knowledge into methods to perform EIA/ELISA.  
Traditional ELISA typically involves chromogenic reporters and substrates that produce some kind of observable color change to indicate the presence of antigen or analyte. Newer ELISA-like techniques use fluorogenic, electrochemiluminescent, and quantitaoppositiontive PCR reporters to create quantifiable signals. These new reporters can have various advantages, including higher sensitivities and multiplexing.   In technical terms, newer assays of this type are not strictly ELISAs, as they are not "enzyme-linked", but are instead linked to some nonenzymatic reporter. However, given that the general principles in these assays are largely similar, they are often grouped in the same category as ELISAs.
In 2012, an ultrasensitive, enzyme-based ELISA test using nanoparticles as a chromogenic reporter was able to give a naked-eye colour signal, from the detection of mere attograms of analyte. A blue color appears for positive results and red color for negative. Note that this detection only can confirm the presence or the absence of analyte, not the actual concentration. 
There are many ELISA tests for particular molecules that use the matching antibodies. ELISA tests are broken into several types of tests based on how the analytes and antibodies are bonded and used.   The major types are described here. 
Direct ELISA Edit
The steps of direct ELISA  follows the mechanism below:
- A buffered solution of the antigen to be tested for is added to each well (usually 96-well plates) of a microtiter plate, where it is given time to adhere to the plastic through charge interactions.
- A solution of nonreacting protein, such as bovine serum albumin or casein, is added to each well in order to cover any plastic surface in the well which remains uncoated by the antigen.
- The primary antibody with an attached (conjugated) enzyme is added, which binds specifically to the test antigen coating the well.
- A substrate for this enzyme is then added. Often, this substrate changes color upon reaction with the enzyme.
- The higher the concentration of the primary antibody present in the serum, the stronger the color change. Often, a spectrometer is used to give quantitative values for color strength.
The enzyme acts as an amplifier even if only few enzyme-linked antibodies remain bound, the enzyme molecules will produce many signal molecules. Within common-sense limitations, the enzyme can go on producing color indefinitely, but the more antibody is bound, the faster the color will develop. A major disadvantage of the direct ELISA is that the method of antigen immobilization is not specific when serum is used as the source of test antigen, all proteins in the sample may stick to the microtiter plate well, so small concentrations of analyte in serum must compete with other serum proteins when binding to the well surface. The sandwich or indirect ELISA provides a solution to this problem, by using a "capture" antibody specific for the test antigen to pull it out of the serum's molecular mixture. [ citation needed ]
ELISA may be run in a qualitative or quantitative format. Qualitative results provide a simple positive or negative result (yes or no) for a sample. The cutoff between positive and negative is determined by the analyst and may be statistical. Two or three times the standard deviation (error inherent in a test) is often used to distinguish positive from negative samples. In quantitative ELISA, the optical density (OD) of the sample is compared to a standard curve, which is typically a serial dilution of a known-concentration solution of the target molecule. For example, if a test sample returns an OD of 1.0, the point on the standard curve that gave OD = 1.0 must be of the same analyte concentration as the sample. [ citation needed ]
The use and meaning of the names "indirect ELISA" and "direct ELISA" differs in the literature and on web sites depending on the context of the experiment. When the presence of an antigen is analyzed, the name "direct ELISA" refers to an ELISA in which only a labelled primary antibody is used, and the term "indirect ELISA" refers to an ELISA in which the antigen is bound by the primary antibody which then is detected by a labeled secondary antibody. In the latter case a sandwich ELISA is clearly distinct from an indirect ELISA. When the "primary" antibody is of interest, e.g. in the case of immunization analyses, this antibody is directly detected by the secondary antibody and the term "indirect ELISA" applies to a setting with two antibodies. [ citation needed ]
Sandwich ELISA Edit
A "sandwich" ELISA is used to detect sample antigen.  The steps are:
- A surface is prepared to which a known quantity of capture antibody is bound.
- Any nonspecific binding sites on the surface are blocked.
- The antigen-containing sample is applied to the plate, and captured by antibody.
- The plate is washed to remove unbound antigen.
- A specific antibody is added, and binds to antigen (hence the 'sandwich': the antigen is stuck between two antibodies). This primary antibody could also be in the serum of a donor to be tested for reactivity towards the antigen.
- Enzyme-linked secondary antibodies are applied as detection antibodies that also bind specifically to the antibody's Fc region (nonspecific).
- The plate is washed to remove the unbound antibody-enzyme conjugates.
- A chemical is added to be converted by the enzyme into a color or fluorescent or electrochemical signal.
- The absorbance or fluorescence or electrochemical signal (e.g., current) of the plate wells is measured to determine the presence and quantity of antigen.
The image to the right includes the use of a secondary antibody conjugated to an enzyme, though, in the technical sense, this is not necessary if the primary antibody is conjugated to an enzyme (which would be direct ELISA). However, the use of a secondary-antibody conjugate avoids the expensive process of creating enzyme-linked antibodies for every antigen one might want to detect. By using an enzyme-linked antibody that binds the Fc region of other antibodies, this same enzyme-linked antibody can be used in a variety of situations. Without the first layer of "capture" antibody, any proteins in the sample (including serum proteins) may competitively adsorb to the plate surface, lowering the quantity of antigen immobilized. Use of the purified specific antibody to attach the antigen to the plastic eliminates a need to purify the antigen from complicated mixtures before the measurement, simplifying the assay, and increasing the specificity and the sensitivity of the assay. A sandwich ELISA used for research often needs validation because of the risk of false positive results. 
Competitive ELISA Edit
A third use of ELISA is through competitive binding. The steps for this ELISA are somewhat different from the first two examples:
Unlabeled antibody is incubated in the presence of its antigen (sample).
- These bound antibody/antigen complexes are then added to an antigen-coated well.
- The plate is washed, so unbound antibodies are removed. (The more antigen in the sample, the more Ag-Ab complexes are formed and so there are less unbound antibodies available to bind to the antigen in the well, hence "competition".)
- The secondary antibody, specific to the primary antibody, is added. This second antibody is coupled to the enzyme.
- A substrate is added, and remaining enzymes elicit a chromogenic or fluorescent signal.
- The reaction is stopped to prevent eventual saturation of the signal.
Some competitive ELISA kits include enzyme-linked antigen rather than enzyme-linked antibody. The labeled antigen competes for primary antibody binding sites with the sample antigen (unlabeled). The less antigen in the sample, the more labeled antigen is retained in the well and the stronger the signal.
Commonly, the antigen is not first positioned in the well.
For the detection of HIV antibodies, the wells of microtiter plate are coated with the HIV antigen. Two specific antibodies are used, one conjugated with enzyme and the other present in serum (if serum is positive for the antibody). Cumulative competition occurs between the two antibodies for the same antigen, causing a stronger signal to be seen. Sera to be tested are added to these wells and incubated at 37 °C, and then washed. If antibodies are present, the antigen-antibody reaction occurs. No antigen is left for the enzyme-labelled specific HIV antibodies. These antibodies remain free upon addition and are washed off during washing. Substrate is added, but there is no enzyme to act on it, so a positive result shows no color change.
Reverse ELISA Edit
A fourth ELISA test does not use the traditional wells. This test leaves the antigens suspended in the test fluid.  
- Unlabeled antibody is incubated in the presence of its antigen (sample)
- A sufficient incubation period is provided to allow the antibodies to bind to the antigens.
- The sample is then passed through the Scavenger container. This can be a test tube or a specifically designed flow through channel. The surface of the Scavenger container or channel has “Scavenger Antigens” bound to it. These can be identical or sufficiently similar to the primary antigens that the free antibodies will bind.
- The Scavenger container must have sufficient surface area and sufficient time to allow the Scavenger Antigens to bind to all the excess Antibodies introduced into the sample.
- The sample, that now contains the tagged and bound antibodies, is passed through a detector. This device can be a flow cytometer or other device that illuminates the tags and registers the response. 
This test allows multiple antigens to be tagged and counted at the same time. This allows specific strains of bacteria to be identified by two (or more) different color tags. If both tags are present on a cell, then the cell is that specific strain. If only one is present, it is not.
This test is done, generally, one test at a time and cannot be done with the microtiter plate. The equipment needed is usually less complicated and can be used in the field.
The following table lists the enzymatic markers commonly used in ELISA assays, which allow the results of the assay to be measured upon completion.
- OPD (o-phenylenediamine dihydrochloride) turns amber to detect HRP (Horseradish Peroxidase), which is often used to as a conjugated protein. 
- TMB (3,3',5,5'-tetramethylbenzidine) turns blue when detecting HRP and turns yellow after the addition of sulfuric or phosphoric acid. 
- ABTS (2,2'-Azinobis [3-ethylbenzothiazoline-6-sulfonic acid]-diammonium salt) turns green when detecting HRP. 
- PNPP (p-Nitrophenyl Phosphate, Disodium Salt) turns yellow when detecting alkaline phosphatase. 
Because the ELISA can be performed to evaluate either the presence of antigen or the presence of antibody in a sample, it is a useful tool for determining serum antibody concentrations (such as with the HIV test  or West Nile virus). It has also found applications in the food industry in detecting potential food allergens, such as milk, peanuts, walnuts, almonds, and eggs  and as serological blood test for coeliac disease.   ELISA can also be used in toxicology as a rapid presumptive screen for certain classes of drugs.
The ELISA was the first screening test widely used for HIV because of its high sensitivity. In an ELISA, a person's serum is diluted 400 times and applied to a plate to which HIV antigens are attached. If antibodies to HIV are present in the serum, they may bind to these HIV antigens. The plate is then washed to remove all other components of the serum. A specially prepared "secondary antibody"—an antibody that binds to other antibodies—is then applied to the plate, followed by another wash. This secondary antibody is chemically linked in advance to an enzyme.
Thus, the plate will contain enzyme in proportion to the amount of secondary antibody bound to the plate. A substrate for the enzyme is applied, and catalysis by the enzyme leads to a change in color or fluorescence. ELISA results are reported as a number the most controversial aspect of this test is determining the "cut-off" point between a positive and a negative result.
A cut-off point may be determined by comparing it with a known standard. If an ELISA test is used for drug screening at workplace, a cut-off concentration, 50 ng/ml, for example, is established, and a sample containing the standard concentration of analyte will be prepared. Unknowns that generate a stronger signal than the known sample are "positive." Those that generate weaker signal are "negative".
There are ELISA tests to detect various kind of diseases, such as dengue, malaria, Chagas disease  , Johne's disease, and others.  ELISA tests also are extensively employed for in vitro diagnostics in medical laboratories. The other uses of ELISA include:
1. You will receive a small tray filled with an agar mold. *See below for directions* Avoid handling the agar with your bare hands and use a scalpel and tweezers to cut three agar cubes with the following approximate dimensions. Save your agar, you will need it later!
2. Measure your cubes (the actual dimensions may not be perfect, depending on how you cut it) and determine the surface area, the volume, and the SA:V ratio. Record on data table.
3. Drop each block into a separate beaker (or container) of vinegar. The agar has been infused with a chemical called bromothymol blue, the blue will turn to a yellow in the presence of acid. You will be able to observe this change with your cubes. Record the time it takes for the blue to completely disappear.
- Each group will acquire three agar cubes: A 3cm cube, a 2cm cube, and a 1cm cube. CUT AS ACCURATELY AS POSSIBLE. (This may be already completed for you.)
- Place cubes into a beaker and submerge with 200 ml NaOH.
- Let the cubes soak for approximately 10 minutes.
- Periodically, gently stir the solution, or turn the cubes over.
- After 10 minutes, remove the NaOH solution.
- Blot the cubes with a paper towel.
- Promptly cut each cube in half and measure the depth to which the pink color has penetrated. Sketch each block&rsquos cross-section.
- Record the volume that has remained white in color.
- Do the following calculations for each cube and complete the following data table:
Cube volume (cm 3 )
(cm 3 )
Sketch of each
Volume of the diffused cube
( Vtotal &ndash Vwhite ) =
Surface Area: Volume
(from the previous table)
Why Pygmies Are Small
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The Grim Reaper can cut life short and, under the right circumstances, whittle those still standing down to the size of pygmies. That’s the controversial conclusion of a new study, published in the October Current Anthropology, that found that stature declined as death rates rose in three small-bodied populations over a 115-year period.
“We provide the first evidence that pygmy body sizes vary considerably over time, that they correlate strongly with mortality rates and that increasing mortality rates lead to even greater reductions of body size,” says Jay Stock of the University of Cambridge in England.
Stock and Andrea Migliano, both anthropologists at the University of Cambridge, say that their findings support a scenario in which most females are able to reproduce at relatively young ages, probably in response to high mortality rates, This physical trait then becomes more common from one generation to the next. Early-maturing bodies divert physiological resources away from growth, yielding small bodies as a side effect, the researchers hypothesize.
Critics of this argument suspect that environmental challenges, such as nutritional deficiencies or cramped forest quarters, prompted the evolution of short-statured populations.
Researchers have traditionally defined pygmies as populations with an average adult male height of no more than 155 centimeters, or about 5 feet, 1 inch. Hunter-gatherer groups classified as pygmies live in various regions, including Africa, Indonesia, the Philippines and the Andaman Islands, which lie southeast of Burma.
Stock and Migliano analyzed data from 11 British government and anthropological studies of Andaman Islanders conducted between 1871 and 1986. Investigations included a range of health and physical measures for 604 individuals from three pygmy groups — the Great Andamanese, the Onge and the Jarawa. Data also included population approximations for each group across time.
Despite describing a small number of people who may have been assessed with varying degrees of accuracy, these studies provide the only long-term glimpse of growth changes within different pygmy groups, Stock says.
British colonies were first established on the Andaman Islands in 1858 and remained until 1947. Onge and Jarawa pygmies, who lived on separate islands, retreated into forests to avoid the British. Great Andamanese pygmies befriended the newcomers.
As a result, Great Andamanese individuals were exposed to infectious diseases against which they had no defense, including influenza, tuberculosis, measles and syphilis. Their approximate numbers dropped from 6,000 in 1858 to 600 in 1900. A low of 19 Great Andamanese individuals was recorded during the 1960s, but the population survives.
British historical records show that average heights for the Great Andamanese dropped markedly during the period of increased mortality, Stock and Migliano say. From 1879 to 1927, the average height of men who were measured decreased at a rate equivalent to 4.7 centimeters, or nearly 2 inches, every 100 years. Measured height declines for women were equivalent to 1.8 centimeters, or almost three-quarters of an inch, every 100 years.
Data from the 19th century were unavailable for the other two pygmy groups that avoided the British. But Onge men and women displayed average height increases from 1927 to 1962, after British attempts to interact with them had stopped. Onge population numbers declined from 1901 to 1951, although not as steeply as among the Great Andamanese.
Jarawa individuals were first measured in 1985. Average heights of 155 centimeters for men and 147 centimeters, or about 4 feet, 10 inches, for women exceeded all average heights recorded for the other two pygmy groups.
Population estimates for the Jarawa held stable during the colonial period, the researchers say.
A related 2007 study led by Migliano reported that pygmies in Africa and the Philippines tend to stop growing by early adolescence, have low life expectancies and begin reproducing at younger ages than taller hunter-gatherers. That pattern of findings also fits the idea that pygmy-sized bodies occur as a by-product of an evolved tendency for women to become fertile early in life, Stock says.
Ancient precursors Edit
The possible existence of microscopic organisms was discussed for many centuries before their discovery in the 17th century. By the fifth century BC, the Jains of present-day India postulated the existence of tiny organisms called nigodas.  These nigodas are said to be born in clusters they live everywhere, including the bodies of plants, animals, and people and their life lasts only for a fraction of a second.  According to the Jain leader Mahavira, the humans destroy these nigodas on a massive scale, when they eat, breathe, sit, and move.  Many modern Jains assert that Mahavira's teachings presage the existence of microorganisms as discovered by modern science. 
The earliest known idea to indicate the possibility of diseases spreading by yet unseen organisms was that of the Roman scholar Marcus Terentius Varro in a 1st-century BC book titled On Agriculture in which he called the unseen creatures animalcules, and warns against locating a homestead near a swamp: 
… and because there are bred certain minute creatures that cannot be seen by the eyes, which float in the air and enter the body through the mouth and nose and they cause serious diseases. 
In The Canon of Medicine (1020), Avicenna suggested that tuberculosis and other diseases might be contagious.  
Early modern Edit
My work, which I've done for a long time, was not pursued in order to gain the praise I now enjoy, but chiefly from a craving after knowledge, which I notice resides in me more than in most other men. And therewithal, whenever I found out anything remarkable, I have thought it my duty to put down my discovery on paper, so that all ingenious people might be informed thereof.
Antony van Leeuwenhoek remains one of the most imperfectly understood figures in the origins of experimental biology. The popular view is that Leeuwenhoek worked in a manner that was essentially crude and undisciplined, using untried methods of investigation that were lacking in refinement and objectivity. He has often been designated as a 'dilettante.' His microscopes, furthermore, have been described as primitive and doubt has been expressed over his ability to have made many of the observations attributed to him. Recent research shows these views to be erroneous. His work was carried out conscientiously, and the observations were recorded with painstaking diligence. Though we may see evidence of his globulist understanding of organic matter (this view has frequently been cited as evidence of his observational inadequacies), this minor preoccupation cannot detract from two firm principles that underlie his work: (a) a clear ability to construct experimental procedures which were, for their time, rational and repeatable, and (b) a willingness both to fly in the face of received opinion – for example, over the question of spontaneous generation – and to abandon a previously held belief in the light of new evidence. In his method of analysing a problem, Leeuwenhoek was able to lay many of the ground rules of experimentation and did much to found, not only the science of microscopy, but also the philosophy of biological experimentation.
Leeuwenhoek is universally acknowledged as the father of microbiology. He discovered both protists and bacteria. More than being the first to see this unimagined world of ‘animalcules', he was the first even to think of looking—certainly, the first with the power to see. Using his own deceptively simple, single-lensed microscopes, he did not merely observe, but conducted ingenious experiments, exploring and manipulating his microscopic universe with a curiosity that belied his lack of a map or bearings. Leeuwenhoek was a pioneer, a scientist of the highest calibre, yet his reputation suffered at the hands of those who envied his fame or scorned his unschooled origins, as well as through his own mistrustful secrecy of his methods, which opened a world that others could not comprehend.
Akshamsaddin (Turkish scientist) mentioned the microbe in his work Maddat ul-Hayat (The Material of Life) about two centuries prior to Antonie Van Leeuwenhoek's discovery through experimentation:
It is incorrect to assume that diseases appear one by one in humans. Disease infects by spreading from one person to another. This infection occurs through seeds that are so small they cannot be seen but are alive.  
In 1546, Girolamo Fracastoro proposed that epidemic diseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or even without contact over long distances. 
Antonie Van Leeuwenhoek is considered to be the father of microbiology. He was the first in 1673 to discover and conduct scientific experiments with microorganisms, using simple single-lensed microscopes of his own design.     Robert Hooke, a contemporary of Leeuwenhoek, also used microscopy to observe microbial life in the form of the fruiting bodies of moulds. In his 1665 book Micrographia, he made drawings of studies, and he coined the term cell. 
19th century Edit
Louis Pasteur (1822–1895) exposed boiled broths to the air, in vessels that contained a filter to prevent particles from passing through to the growth medium, and also in vessels without a filter, but with air allowed in via a curved tube so dust particles would settle and not come in contact with the broth. By boiling the broth beforehand, Pasteur ensured that no microorganisms survived within the broths at the beginning of his experiment. Nothing grew in the broths in the course of Pasteur's experiment. This meant that the living organisms that grew in such broths came from outside, as spores on dust, rather than spontaneously generated within the broth. Thus, Pasteur refuted the theory of spontaneous generation and supported the germ theory of disease. 
In 1876, Robert Koch (1843–1910) established that microorganisms can cause disease. He found that the blood of cattle that were infected with anthrax always had large numbers of Bacillus anthracis. Koch found that he could transmit anthrax from one animal to another by taking a small sample of blood from the infected animal and injecting it into a healthy one, and this caused the healthy animal to become sick. He also found that he could grow the bacteria in a nutrient broth, then inject it into a healthy animal, and cause illness. Based on these experiments, he devised criteria for establishing a causal link between a microorganism and a disease and these are now known as Koch's postulates.  Although these postulates cannot be applied in all cases, they do retain historical importance to the development of scientific thought and are still being used today. 
The discovery of microorganisms such as Euglena that did not fit into either the animal or plant kingdoms, since they were photosynthetic like plants, but motile like animals, led to the naming of a third kingdom in the 1860s. In 1860 John Hogg called this the Protoctista, and in 1866 Ernst Haeckel named it the Protista.   
The work of Pasteur and Koch did not accurately reflect the true diversity of the microbial world because of their exclusive focus on microorganisms having direct medical relevance. It was not until the work of Martinus Beijerinck and Sergei Winogradsky late in the 19th century that the true breadth of microbiology was revealed.  Beijerinck made two major contributions to microbiology: the discovery of viruses and the development of enrichment culture techniques.  While his work on the tobacco mosaic virus established the basic principles of virology, it was his development of enrichment culturing that had the most immediate impact on microbiology by allowing for the cultivation of a wide range of microbes with wildly different physiologies. Winogradsky was the first to develop the concept of chemolithotrophy and to thereby reveal the essential role played by microorganisms in geochemical processes.  He was responsible for the first isolation and description of both nitrifying and nitrogen-fixing bacteria.  French-Canadian microbiologist Felix d'Herelle co-discovered bacteriophages and was one of the earliest applied microbiologists. 
Microorganisms can be found almost anywhere on Earth. Bacteria and archaea are almost always microscopic, while a number of eukaryotes are also microscopic, including most protists, some fungi, as well as some micro-animals and plants. Viruses are generally regarded as not living and therefore not considered as microorganisms, although a subfield of microbiology is virology, the study of viruses.   
Single-celled microorganisms were the first forms of life to develop on Earth, approximately 3.5 billion years ago.    Further evolution was slow,  and for about 3 billion years in the Precambrian eon, (much of the history of life on Earth), all organisms were microorganisms.   Bacteria, algae and fungi have been identified in amber that is 220 million years old, which shows that the morphology of microorganisms has changed little since at least the Triassic period.  The newly discovered biological role played by nickel, however – especially that brought about by volcanic eruptions from the Siberian Traps – may have accelerated the evolution of methanogens towards the end of the Permian–Triassic extinction event. 
Microorganisms tend to have a relatively fast rate of evolution. Most microorganisms can reproduce rapidly, and bacteria are also able to freely exchange genes through conjugation, transformation and transduction, even between widely divergent species.  This horizontal gene transfer, coupled with a high mutation rate and other means of transformation, allows microorganisms to swiftly evolve (via natural selection) to survive in new environments and respond to environmental stresses. This rapid evolution is important in medicine, as it has led to the development of multidrug resistant pathogenic bacteria, superbugs, that are resistant to antibiotics. 
A possible transitional form of microorganism between a prokaryote and a eukaryote was discovered in 2012 by Japanese scientists. Parakaryon myojinensis is a unique microorganism larger than a typical prokaryote, but with nuclear material enclosed in a membrane as in a eukaryote, and the presence of endosymbionts. This is seen to be the first plausible evolutionary form of microorganism, showing a stage of development from the prokaryote to the eukaryote.  
Archaea are prokaryotic unicellular organisms, and form the first domain of life, in Carl Woese's three-domain system. A prokaryote is defined as having no cell nucleus or other membrane bound-organelle. Archaea share this defining feature with the bacteria with which they were once grouped. In 1990 the microbiologist Woese proposed the three-domain system that divided living things into bacteria, archaea and eukaryotes,  and thereby split the prokaryote domain.
Archaea differ from bacteria in both their genetics and biochemistry. For example, while bacterial cell membranes are made from phosphoglycerides with ester bonds, archaean membranes are made of ether lipids.  Archaea were originally described as extremophiles living in extreme environments, such as hot springs, but have since been found in all types of habitats.  Only now are scientists beginning to realize how common archaea are in the environment, with Crenarchaeota being the most common form of life in the ocean, dominating ecosystems below 150 m in depth.   These organisms are also common in soil and play a vital role in ammonia oxidation. 
The combined domains of archaea and bacteria make up the most diverse and abundant group of organisms on Earth and inhabit practically all environments where the temperature is below +140 °C. They are found in water, soil, air, as the microbiome of an organism, hot springs and even deep beneath the Earth's crust in rocks.  The number of prokaryotes is estimated to be around five nonillion, or 5 × 10 30 , accounting for at least half the biomass on Earth. 
The biodiversity of the prokaryotes is unknown, but may be very large. A May 2016 estimate, based on laws of scaling from known numbers of species against the size of organism, gives an estimate of perhaps 1 trillion species on the planet, of which most would be microorganisms. Currently, only one-thousandth of one percent of that total have been described.  Archael cells of some species aggregate and transfer DNA from one cell to another through direct contact, particularly under stressful environmental conditions that cause DNA damage.  
Bacteria like archaea are prokaryotic – unicellular, and having no cell nucleus or other membrane-bound organelle. Bacteria are microscopic, with a few extremely rare exceptions, such as Thiomargarita namibiensis.  Bacteria function and reproduce as individual cells, but they can often aggregate in multicellular colonies.  Some species such as myxobacteria can aggregate into complex swarming structures, operating as multicellular groups as part of their life cycle,  or form clusters in bacterial colonies such as E.coli.
Their genome is usually a circular bacterial chromosome – a single loop of DNA, although they can also harbor small pieces of DNA called plasmids. These plasmids can be transferred between cells through bacterial conjugation. Bacteria have an enclosing cell wall, which provides strength and rigidity to their cells. They reproduce by binary fission or sometimes by budding, but do not undergo meiotic sexual reproduction. However, many bacterial species can transfer DNA between individual cells by a horizontal gene transfer process referred to as natural transformation.  Some species form extraordinarily resilient spores, but for bacteria this is a mechanism for survival, not reproduction. Under optimal conditions bacteria can grow extremely rapidly and their numbers can double as quickly as every 20 minutes. 
Most living things that are visible to the naked eye in their adult form are eukaryotes, including humans. However, many eukaryotes are also microorganisms. Unlike bacteria and archaea, eukaryotes contain organelles such as the cell nucleus, the Golgi apparatus and mitochondria in their cells. The nucleus is an organelle that houses the DNA that makes up a cell's genome. DNA (Deoxyribonucleic acid) itself is arranged in complex chromosomes.  Mitochondria are organelles vital in metabolism as they are the site of the citric acid cycle and oxidative phosphorylation. They evolved from symbiotic bacteria and retain a remnant genome.  Like bacteria, plant cells have cell walls, and contain organelles such as chloroplasts in addition to the organelles in other eukaryotes. Chloroplasts produce energy from light by photosynthesis, and were also originally symbiotic bacteria. 
Unicellular eukaryotes consist of a single cell throughout their life cycle. This qualification is significant since most multicellular eukaryotes consist of a single cell called a zygote only at the beginning of their life cycles. Microbial eukaryotes can be either haploid or diploid, and some organisms have multiple cell nuclei. 
Unicellular eukaryotes usually reproduce asexually by mitosis under favorable conditions. However, under stressful conditions such as nutrient limitations and other conditions associated with DNA damage, they tend to reproduce sexually by meiosis and syngamy. 
Of eukaryotic groups, the protists are most commonly unicellular and microscopic. This is a highly diverse group of organisms that are not easy to classify.   Several algae species are multicellular protists, and slime molds have unique life cycles that involve switching between unicellular, colonial, and multicellular forms.  The number of species of protists is unknown since only a small proportion has been identified. Protist diversity is high in oceans, deep sea-vents, river sediment and an acidic river, suggesting that many eukaryotic microbial communities may yet be discovered.  
The fungi have several unicellular species, such as baker's yeast (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe). Some fungi, such as the pathogenic yeast Candida albicans, can undergo phenotypic switching and grow as single cells in some environments, and filamentous hyphae in others. 
The green algae are a large group of photosynthetic eukaryotes that include many microscopic organisms. Although some green algae are classified as protists, others such as charophyta are classified with embryophyte plants, which are the most familiar group of land plants. Algae can grow as single cells, or in long chains of cells. The green algae include unicellular and colonial flagellates, usually but not always with two flagella per cell, as well as various colonial, coccoid, and filamentous forms. In the Charales, which are the algae most closely related to higher plants, cells differentiate into several distinct tissues within the organism. There are about 6000 species of green algae. 
Microorganisms are found in almost every habitat present in nature, including hostile environments such as the North and South poles, deserts, geysers, and rocks. They also include all the marine microorganisms of the oceans and deep sea. Some types of microorganisms have adapted to extreme environments and sustained colonies these organisms are known as extremophiles. Extremophiles have been isolated from rocks as much as 7 kilometres below the Earth's surface,  and it has been suggested that the amount of organisms living below the Earth's surface is comparable with the amount of life on or above the surface.  Extremophiles have been known to survive for a prolonged time in a vacuum, and can be highly resistant to radiation, which may even allow them to survive in space.  Many types of microorganisms have intimate symbiotic relationships with other larger organisms some of which are mutually beneficial (mutualism), while others can be damaging to the host organism (parasitism). If microorganisms can cause disease in a host they are known as pathogens and then they are sometimes referred to as microbes. Microorganisms play critical roles in Earth's biogeochemical cycles as they are responsible for decomposition and nitrogen fixation. 
Bacteria use regulatory networks that allow them to adapt to almost every environmental niche on earth.   A network of interactions among diverse types of molecules including DNA, RNA, proteins and metabolites, is utilised by the bacteria to achieve regulation of gene expression. In bacteria, the principal function of regulatory networks is to control the response to environmental changes, for example nutritional status and environmental stress.  A complex organization of networks permits the microorganism to coordinate and integrate multiple environmental signals. 
Extremophiles are microorganisms that have adapted so that they can survive and even thrive in extreme environments that are normally fatal to most life-forms. Thermophiles and hyperthermophiles thrive in high temperatures. Psychrophiles thrive in extremely low temperatures. – Temperatures as high as 130 °C (266 °F),  as low as −17 °C (1 °F)  Halophiles such as Halobacterium salinarum (an archaean) thrive in high salt conditions, up to saturation.  Alkaliphiles thrive in an alkaline pH of about 8.5–11.  Acidophiles can thrive in a pH of 2.0 or less.  Piezophiles thrive at very high pressures: up to 1,000–2,000 atm, down to 0 atm as in a vacuum of space.  A few extremophiles such as Deinococcus radiodurans are radioresistant,  resisting radiation exposure of up to 5k Gy. Extremophiles are significant in different ways. They extend terrestrial life into much of the Earth's hydrosphere, crust and atmosphere, their specific evolutionary adaptation mechanisms to their extreme environment can be exploited in biotechnology, and their very existence under such extreme conditions increases the potential for extraterrestrial life. 
In soil Edit
The nitrogen cycle in soils depends on the fixation of atmospheric nitrogen. This is achieved by a number of diazotrophs. One way this can occur is in the root nodules of legumes that contain symbiotic bacteria of the genera Rhizobium, Mesorhizobium, Sinorhizobium, Bradyrhizobium, and Azorhizobium. 
The roots of plants create a narrow region known as the rhizosphere that supports many microorganisms known as the root microbiome. 
A lichen is a symbiosis of a macroscopic fungus with photosynthetic microbial algae or cyanobacteria.  
Microorganisms are useful in producing foods, treating waste water, creating biofuels and a wide range of chemicals and enzymes. They are invaluable in research as model organisms. They have been weaponised and sometimes used in warfare and bioterrorism. They are vital to agriculture through their roles in maintaining soil fertility and in decomposing organic matter.
Food production Edit
Microorganisms are used in a fermentation process to make yoghurt, cheese, curd, kefir, ayran, xynogala, and other types of food. Fermentation cultures provide flavour and aroma, and inhibit undesirable organisms.  They are used to leaven bread, and to convert sugars to alcohol in wine and beer. Microorganisms are used in brewing, wine making, baking, pickling and other food-making processes. 
Some industrial uses of Microorganisms:
|Product||Contribution of Microorganisms|
|Cheese||Growth of microorganisms contributes to ripening and flavor. The flavor and appearance of a particular cheese is due in large part to the microorganisms associated with it. Lactobacillus Bulgaricus is one of the microbes used in production of diary products|
|Alcoholic beverages||yeast is used to convert sugar, grape juice, or malt-treated grain into alcohol. other microorganisms may also be used a mold converts starch into sugar to make the Japanese rice wine, sake. Acetobacter Aceti a kind of bacterium is used in production of Alcoholic beverages|
|Vinegar||Certain bacteria are used to convert alcohol into acetic acid, which gives vinegar its acid taste. Acetobacter Aceti is used on production of vinegar which gives vinegar odor of alcohol and alcoholic taste|
|Citric acid||Certain fungi are used to make citric acid, a common ingredient of soft drinks and other foods.|
|Vitamins||Microorganisms are used to make vitamins, including C, B2 , B12.|
|Antibiotics||With only a few exceptions, microorganisms are used to make antibiotics. Penicillin, Amoxicillin, Tetracycline and Erythromycin|
Water treatment Edit
These depend for their ability to clean up water contaminated with organic material on microorganisms that can respire dissolved substances. Respiration may be aerobic, with a well-oxygenated filter bed such as a slow sand filter.  Anaerobic digestion by methanogens generate useful methane gas as a by-product. 
Microorganisms are used in fermentation to produce ethanol,  and in biogas reactors to produce methane.  Scientists are researching the use of algae to produce liquid fuels,  and bacteria to convert various forms of agricultural and urban waste into usable fuels. 
Chemicals, enzymes Edit
Microorganisms are used to produce many commercial and industrial chemicals, enzymes and other bioactive molecules. Organic acids produced on a large industrial scale by microbial fermentation include acetic acid produced by acetic acid bacteria such as Acetobacter aceti, butyric acid made by the bacterium Clostridium butyricum, lactic acid made by Lactobacillus and other lactic acid bacteria,  and citric acid produced by the mould fungus Aspergillus niger. 
Microorganisms are used to prepare bioactive molecules such as Streptokinase from the bacterium Streptococcus,  Cyclosporin A from the ascomycete fungus Tolypocladium inflatum,  and statins produced by the yeast Monascus purpureus. 
Microorganisms are essential tools in biotechnology, biochemistry, genetics, and molecular biology. The yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe are important model organisms in science, since they are simple eukaryotes that can be grown rapidly in large numbers and are easily manipulated.  They are particularly valuable in genetics, genomics and proteomics.   Microorganisms can be harnessed for uses such as creating steroids and treating skin diseases. Scientists are also considering using microorganisms for living fuel cells,  and as a solution for pollution. 
In the Middle Ages, as an early example of biological warfare, diseased corpses were thrown into castles during sieges using catapults or other siege engines. Individuals near the corpses were exposed to the pathogen and were likely to spread that pathogen to others. 
In modern times, bioterrorism has included the 1984 Rajneeshee bioterror attack  and the 1993 release of anthrax by Aum Shinrikyo in Tokyo. 
Microbes can make nutrients and minerals in the soil available to plants, produce hormones that spur growth, stimulate the plant immune system and trigger or dampen stress responses. In general a more diverse set of soil microbes results in fewer plant diseases and higher yield. 
Human gut flora Edit
Microorganisms can form an endosymbiotic relationship with other, larger organisms. For example, microbial symbiosis plays a crucial role in the immune system. The microorganisms that make up the gut flora in the gastrointestinal tract contribute to gut immunity, synthesize vitamins such as folic acid and biotin, and ferment complex indigestible carbohydrates.  Some microorganisms that are seen to be beneficial to health are termed probiotics and are available as dietary supplements, or food additives. 
Microorganisms are the causative agents (pathogens) in many infectious diseases. The organisms involved include pathogenic bacteria, causing diseases such as plague, tuberculosis and anthrax protozoan parasites, causing diseases such as malaria, sleeping sickness, dysentery and toxoplasmosis and also fungi causing diseases such as ringworm, candidiasis or histoplasmosis. However, other diseases such as influenza, yellow fever or AIDS are caused by pathogenic viruses, which are not usually classified as living organisms and are not, therefore, microorganisms by the strict definition. No clear examples of archaean pathogens are known,  although a relationship has been proposed between the presence of some archaean methanogens and human periodontal disease.  Numerous microbial pathogens are capable of sexual processes that appear to facilitate their survival in their infected host. 
Hygiene is a set of practices to avoid infection or food spoilage by eliminating microorganisms from the surroundings. As microorganisms, in particular bacteria, are found virtually everywhere, harmful microorganisms may be reduced to acceptable levels rather than actually eliminated. In food preparation, microorganisms are reduced by preservation methods such as cooking, cleanliness of utensils, short storage periods, or by low temperatures. If complete sterility is needed, as with surgical equipment, an autoclave is used to kill microorganisms with heat and pressure.  
Why are women smaller than men? When anthropology meets evolutionary biology
There are large variations of size among humans but in all populations, men are larger on average than women. For most biologists this fact can be easily explained by the same processes that explain the size dimorphism in large mammals in general and in apes in particular. Due to fights between males for the possession of females, sexual selection has favoured bigger males. Indeed, this factor certainly explains why males are selected for being large but lets aside the question of selection on the female side. Actually, it has been shown that larger females are also favoured by natural selection. This is particularly relevant for women because their probability of dying when giving birth is then reduced. In this paper, the common view that size dimorphism in humans results from the fact that the advantage of being big is stronger for men than for women is challenged by another hypothesis, namely that the difference results from a difference of cost rather than from a difference of benefits. The cost of being big would be higher in women simply because, under gender hierarchical regimes found in all cultures, men are allocated the best food. The interaction between evolutionary forces and cultural practices could then lead to this disadaptive situation.
Why prokaryotes tend to be small as compared to eukaryotic cells
Discuss why prokaryotes tend to be small relative to eukaryotic cells. Discuss why size may be limited in cells of eukaryotic organisms bases on their function. Provide examples and incorporate resources as necessary.
© BrainMass Inc. brainmass.com March 4, 2021, 7:29 pm ad1c9bdddf
Prokaryotic cells are "simple" cells. What I mean by this is that they are "simpler" than eukaryotic cells. Now, don't be misled. The use of "simple" here is only used in a comparative sense. They are still vastly complex organisms, way beyond the knowledge of the entire scientific community in the world today. Think about that. So, "simple" doesn't exactly mean simple.
One of the main reasons why we might postulate that prokaryotic cells are smaller than eukaryotic cells has to do with internal functions. Eukaryotic cells have a significant system of internal membranes in order to divide the cytoplasm into compartments for specialized functions. A prokaryotic cells has no regular endomembrane system therefore, it must remain small. Think about it. From a cell's point of .
Is Having Small Testicles Bad?
Small testicles are a signal that your reproductive system is not operating at peak efficiency.
They’re like the proverbial canary in the coal mine, if you will, demonstrating clearly that your hormones are headed in the wrong direction.
And bad hormone levels will have a negative impact on many things — things you’ll soon be experiencing first hand if your testicles are smaller than they should be.
So if you want a simple answer to your question: Is having small testicles bad….the answer is a clear Yes.
Small Testicles And Ejaculating Less Semen
“The bigger the balls, the more sperm a man will produce,” according to professor of andrology Allen Pacey, who was recently quoted in The Telegraph, a respected British newspaper.
It’s a fairly simple idea, and it makes sense… even if you’re not a health expert who specializes in the biology of balls.
There are a LOT of small testicles out there these days…
Which explains why 1 in 12 men seek fertility help — and 1 in 6 can’t get their lady pregnant when they want to.
If you can grow decent facial hair, have a deep voice and have well-developed musculature, it’s safe to assume that your testicles are in halfway decent shape…
As these are all signs of good testosterone levels and healthy testicles.
Or at least they’re signs that your testicles worked well at one time.
Semen production can fall off with age, especially if you don’t keep your testosterone level high and your estrogen level low.
Balance is the key with these two hormones.
As you probably know, your testicles are where you produce and store your semen. But size isn’t the only thing that impacts semen production.
Many other factors affect semen production and sperm count as well.
Still, it’s accurate to say that when two men have otherwise similar reproductive health, the man with the smaller testicles will ejaculate less semen when he climaxes.
Small Testicles Produce Less Testosterone
It’s right there on WebMD: Low testosterone leads to small testicles.
Another way to say this is that small testicles lead to low testosterone. It’s a catch-22, and both are symptoms of a body not performing at its best.
Over 90 percent of the testosterone running around in your body is produced in your gonads.
You need balls big enough to produce plenty of this crucial male hormone.
Testosterone is literally what puts hair on your chest, builds your muscles, boost the size of your testes (and your penis!) and deepens your voice so you sound like a man.
It also leads to strong bones, better moods and greater energy when in balance with other hormones.
Oh, and did I mention that testosterone is responsible for your sex drive too?
And testosterone concentrations are usually 50 times higher in testicles compared to blood.
Then after age 30, testosterone levels can start to drop, your balls can start to shrink and sex can start to leave your life.
But this isn’t always a natural sign of aging.
It’s something you can correct, no matter how big your balls are now. And you need to correct it….
Because low T is not only associated with small testicles, but also…
- No energy
- No sex drive
- Weak erections
- Loss of muscle
- And more.
And worse, not having enough testosterone can lead to heart disease, osteoporosis and even diabetes.
So if you have small testicles, you can do something about it. And you have to do something if you want to maintain your sex life, your vitality and your health.
Small Testicles Indicate High Estrogen
All men have estrogen in their systems, even though the hormone is associated with feminine characteristics.
All women have testosterone running around in their bloodstreams too.
But when your testes don’t produce enough testosterone, the estrogen that’s naturally in your body starts to take over.
You develop feminine characteristics like breasts, a condition called gynecomastia.
This overall situation is called estrogen dominance, and it shouldn’t happen in healthy men.
In fact, in a pair of recent studies where men were given high doses of estrogen as part of medical treatment, the majority of the subjects experienced testicular shrinkage.
The punch line to this not very funny joke is clear: high estrogen causes small testicles.
And yes, small testicles cause high estrogen.
It’s another catch-22. Higher than normal estrogen, like low T, can cause a variety of problems for men, including:
- Fat gain, including breast growth
- Erectile dysfunction
- Prostate issues, including risk of prostate cancer
- Increased risk of stroke
- And more.
Having small testicles doesn’t always mean you have a high estrogen count, but more often than not this is the case.
If you do have more estrogen than is healthy, there are several natural methods to reduce your estrogen levels.
Is Having Small Testicles Bad Conclusion:
So let me say this again to be completely clear: Is having small testicles bad?
That’s because small balls can mean you aren’t putting out enough sperm, don’t have enough testosterone in your system and have too much of the female hormone estrogen coursing through your veins.
But don’t believe quite everything you read.
There are many articles online that say you can’t do anything about the size of your gonads. But that’s just wrong.
You can make your testicles bigger using a variety of natural methods that are easier than you might imagine.
And you can make those big boys work better too.
When you take care of yourself and take consistent action, you can have a healthier body, better sex drive, better sexual function — and have the balls to do whatever you want with your life.
What's the smallest microchip we can make?
Chris Smith put this question to tech expert Peter Cowley.
Peter - Yeah, that is an interesting question. I'm not quite sure he means microchip. Let’s just do a bit of a background. So first of all, the track width of a transistor nowadays has got down to about 7 nanometres.
Chris - Transistors are the things inside chips that make the computer tick effectively, aren’t they?
Peter - Exactly, yes. Okay. So that’s not actually in production yet. They're down to about 10 nanometres. That’s about 10,000th of a human hair. Its visible light is 40 times big, wider than that with the wavelength of that. But I'm sure that’s not the question because that transistor is just on or off. What we’re probably talking about is microprocessors and I brought in something that’s about the same…
Chris - This is the gadget, isn’t it, that you said to me you'd – you brought this is in. We said at the beginning, Peter has brought a gadget in and he’s going to tell us what it is. This is a big box. It’s probably at 20 centimetres by 15 centimetres and about 5 deep with lots of wires and circuit boards. What is that?
Peter - So, this is the first computer that I developed and built as you can see, very badly built built back in 1975. The reason I brought it in is because it had a processor that had about 4,000 transistors in it called a scamp in fact. This has 32 bytes of memory.
Chris - Gosh! That’s a lot, isn’t it?
Peter - You know, you can't do much with 32 bytes of memory, can you? But I just want to compare that with modern microprocessors or microchips.
Chris - Why did you build that? What did it do?
Peter - I built it because I want to learn how to build a computer. (inaudible) necessarily want going through with it. You have to enter the – on the front side, there are some switches and you have to enter the program on these switches. There are 16 bytes of RAM so you have maximum of 16 instructions and it will switch some LEDs on, Light Emitting Diodes on, on the front. Anyway, that was just an example of that. But nowadays, we’ve got processors that have got billions of transistors in rather than a few thousand. That’s about 600, 700, 800 square millimetres and it got GPUs which are even more. But I think actually…
Chris - That’s Graphic Processing Units.
Peter - Graphic Processing Unit. The question has possibly to do with, how are we going to do in the future? Quantum computing where you’ve got multiple of these quantum bits or these are investment I nearly made down in Cambridge which was storing data of strands of DNA. Then you’ve something, then you’ve got petabyte, you’ve got huge amounts of volume of data, possibly as much as there's on the earth in the size of a bucket really.
Chris - Yeah. The DNA thing at the moment is being held back by the fact that it’s extremely expensive to make and then decode DNA and not…
Peter - Well, to write it is not – well, to read is not too bad because there have been sequences around for years. To write it is…
Chris - Yeah and to make the DNA is very expensive.
Chris - But people are saying it’s a bit like the sort of Rosetta stone. It’s a very long lived, very stable molecule that you could put your information in and you know it will be (crosstalk)
Peter - It will last hundreds of millions of years, exactly for long term storage.