Will eukaryotic RNA fold in the same way in prokaryotes?

Will eukaryotic RNA fold in the same way in prokaryotes?

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As far as I know, there are no specific eukaryotic or prokaryotic factors that aid in RNA folding other than cellular environment (salt and ion concentrations, dissolved molecules, etc). Are there any factors to consider when introducing eukaryotic RNA in prokaryotes? Is it possible to predict the proper shape and folding upon introduction to a prokaryotic cell?

As you have mentioned ions and temperature affect RNA structure. There are also different types of RNA structures and their dependence on ions are different. Mg2+, as Mad Scientist mentioned, stabilizes duplexes; so do monovalent cations like K+ and Na+. However, Mg2+ favors duplex over quadruplex if the same RNA can adopt both these conformations. Dependence on temperature is a trivial case.

Ions and temperature should be more or less same for prokaryotes and eukaryotes unless we are talking about extremophiles.

Apart from these factors I can think of two other factors that can cause difference in RNA structure between prokaryotes and eukaryotes:

  • Osmolytes
  • RNA binding proteins/chaperones (Already mentioned in comments by Mad Scientist)


It has been shown that TMAO (Trimethylamine N-oxide) stabilizes RNA secondary structures. The metabolism of TMAO is different in prokaryotes and eukaryotes.

From this paper:

Although eukaryototes can endogenously produce L-carnitine, only prokaryotic organisms can catabolize L-carnitine11. A role for intestinal microbiota in TMAO production from dietary carnitine was first suggested by studies in rats; moreover, while TMAO production from alternative dietary trimethylamines has been suggested in humans, a role for microbiota in production of TMAO from dietary L-carnitine in humans had not yet been demonstrated30-32. The present studies reveal an obligatory role of gut microbiota in the production of TMAO from ingested L-carnitine in humans (Fig. 6c)

I cannot ascertain that this will affect RNA folding but is possible.


This is something that you can be certain about. Some RNAs require protein counterparts to adopt a functionally capable structure. In the absence of the protein they may not form the relevant structure. So if an RNA needs Hfq then you have to express it in the eukaryotic system where you want to use the RNA (and converse).

Will eukaryotic RNA fold in the same way in prokaryotes? - Biology

Prokaryotes do not have membrane-enclosed nuclei. Therefore, the processes of transcription, translation, and mRNA degradation can all occur simultaneously. The intracellular level of a bacterial protein can quickly be amplified by multiple transcription and translation events occurring concurrently on the same DNA template. Prokaryotic transcription often covers more than one gene and produces polycistronic mRNAs that specify more than one protein.

Our discussion here will exemplify transcription by describing this process in Escherichia coli, a well-studied bacterial species. Although some differences exist between transcription in E. coli and transcription in archaea, an understanding of E. coli transcription can be applied to virtually all bacterial species.

Will eukaryotic RNA fold in the same way in prokaryotes? - Biology

Comparisons between bacterial and RNA polymerase II have been performed. Similarity in sequence has been shown between alpha, Rpb3, and Rpb11. Alpha2 binds beta to form a subcomplex that then binds beta’ that form the core enzyme. Rpb3 and Rpb11 also form a subcomplex with Rpb2. The Rpb3 and Rpb11 show the same fold as the alpha subunit in bacterial polymerase. Beta and Rpb2 as well as beta’ and Rpb1 show sequence homology. The pore in which RNA exits and where NTPs comes into the polymerase are conserved as well (4).

Prokaryotes only contain three different promoter elements: -10, -35 promoters, and upstream elements. Eukaryotes contain many different promoter elements: TATA box, initiator elements, downstream core promoter element, CAAT box, and the GC box to name a few. Eukaryotes have three types of RNA polymerases, I, II, and III, and prokaryotes only have one type. Eukaryotes form and initiation complex with the various transcription factors that dissociate after initiation is completed. There is no such structure seen in prokaryotes. Another main difference between the two is that transcription and translation occurs simultaneously in prokaryotes and in eukaryotes the RNA is first transcribed in the nucleus and then translated in the cytoplasm. RNAs from eukaryotes undergo post-transcriptional modifications including: capping, polyadenylation, and splicing. These events do not occur in prokaryotes. mRNAs in prokaryotes tend to contain many different genes on a single mRNA meaning they are polycystronic. Eukaryotes contain mRNAs that are monocystronic. Termination in prokaryotes is done by either rho-dependent or rho-independent mechanisms. In eukaryotes transcription is terminated by two elements: a poly(A) signal and a downstream terminator sequence (7).

What is Eukaryotic Translation

Translation is the second step of eukaryotic gene expression, a separate event from eukaryotic transcription. Transcription and translation occur in two different compartments in eukaryotes. Therefore, the two processes can not occur simultaneously. Eukaryotic mRNAs are monocistronic and are processed in the nucleus by adding a 5′ cap, poly A tail and splicing out of introns before they are released to the cytoplasm. Ribosomal pausing also affects the translation by co-translational folding of the newly synthesising polypeptide chain on the ribosome. This process delays translation, giving time for the translation.

Eukaryotic mRNAs consist of a 5′ cap and poly A tail. Therefore, the initiation of translation occurs in two different ways: cap-dependent initiation and cap-independent initiation. During cap-dependent initiation, the initiation factors bind to the 5′ end of the mRNA. These initiation factors hold the mRNA in the small subunit of the ribosome. During cap-independent initiation, internal ribosome entry sites allow the ribosome trafficking to the start site by direct binding. In eukaryotes, the first binding amino acid is methionine. 40S subunit associates with 60S subunit to form 80S ribosome.

Two elongation factors are involved in eukaryotic translation: eEF-1 and eEF-2. Elongation occurs in a similar way to that of prokaryotes. Termination of the translation is also the same as in the prokaryotic system. But the universal release factor eRF1 is capable of recognising all three stop codons. The release factor, eRF3 helps eRF1 to release the polypeptide chain. Basic steps of the translation are shown in figure 2.

Figure 2: Generalised translation

RNA polymerase is the enzyme responsible for RNA polymerization known as transcription in the living cell. The RNA polymerase is also named as DNA-directed RNA polymerase as it uses DNA as the template. In transcription RNA polymerase normally opens the double-stranded DNA so that one DNA strand can be used as a template for the process of synthesizing RNA molecule. RNA polymerase can give rise to mRNA, rRNA, and tRNA. Transcription factors and transcription mediated complex are guiding the RNA polymerase in the transcription process. The transcription has three steps initiation, elongation, and termination. This can be highlighted as the difference between Prokaryotic and Eukaryotic RNA Polymerase.

Download the PDF Version of Prokaryotic vs Eukaryotic RNA Polymerase

You can download PDF version of this article and use it for offline purposes as per citation note. Please download PDF version here Difference Between Prokaryotic and Eukaryotic RNA Polymerase


1.Nature News, Nature Publishing Group. Available here
2.“RNA polymerase.” Wikipedia, Wikimedia Foundation, 11 Dec. 2017. Available here

Image Courtesy:

1.’RNAP TEC small’By Abbondanzieri, ( Public Domain) via Commons Wikimedia
2.’Label RNA pol II’ By JWSchmidt, (Public Domain) via Commons Wikimedia


As elongation proceeds, the DNA is continuously unwound ahead of the core enzyme as the hydrogen bonds that connect the complementary base pairs in the DNA double helix are broken (Figure 2). The DNA is rewound behind the core enzyme as the hydrogen bonds are reformed. The base pairing between DNA and RNA is not stable enough to maintain the stability of the mRNA synthesis components. Instead, the RNA polymerase acts as a stable linker between the DNA template and the newly forming RNA strand to ensure that elongation is not interrupted prematurely.

Figure 2 During elongation, RNA polymerase tracks along the DNA template, synthesizes mRNA in the 5′ to 3′ direction, and unwinds then rewinds the DNA as it is read.

Will eukaryotic RNA fold in the same way in prokaryotes? - Biology

C2006/F2402 '11 OUTLINE OF LECTURE #9

(c) 2011 Dr. Alice Heicklen & Dr. Deborah Mowshowitz, Columbia University, New York, NY . Last update 02/18/2011 09:34 AM .

Handouts: 9A Regulatory Elements & Picture of a typical Eukaryotic Gene (in Word, not pdf)
9B Transcription Complex & Modular Regulation -- this handout is posted in Courseworks

I. How Do you turn a Eukaryotic Gene On?

A. The Problem: Need to unfold/loosen chromatin before transcription is possible. Can't just add RNA polymerase (& basal TFs) to DNA and start transcription. DNA is in chromatin and must be made accessible.

B. So how can transcription occur?

1. Need multiple steps not found in prokaryotes

a. Must de-condense (loosen up) euchromatin to a transcribable state = relatively loose (compared to heterochromatin and compared to inactive euchromatin). Pull out 30nm fiber to beads-on-a-string stage?

b. Many transcription factors (TF's) must bind to DNA first -- before RNA polymerase binds.

c. Polymerase must bind to TF's (not directly to the DNA) to get actual transcription.

2. What changes state of chromatin? (To tighten or loosen.)

a. Remodeling proteins: these are responsible for moving and/or loosening up nucleosomes. See Sadava fig. 16.19 (14.17). These may be a separate set of proteins or the TF's that activate the modifying enzymes.

b. Enzymes that modify histone tails. Changes in modification may have a direct effect and/or affect binding of regulatory proteins. Some examples:

(1). Phosphorylation of H1 occurs in M changes in kinase and phosphatase activity affect state of histones and folding of chromatin in parallel with changes in lamins as discussed last time.

(2). Acetylation of lys side chains of histones. Acetylation of histones → more active, looser chromatin. Acetylation of H3 & H4 is higher in active chromatin.

(3). Methylation -- Effects depend which amino acid side chains in which position of the protein are methylated -- some modifications increase likelihood of transcription, and some decrease it. (DNA can be methylated too see below.)

c. Methylation of DNA -- In most organisms, both DNA and histones can be methylated. (Methyl groups can be added to C's in DNA as well as side chains of AA.)

Usually, but not always, DNA methylation is higher in more inactive/condensed chromatin.

In some organisms, there is no methylation of DNA.

d. Overall histone modification 'code' -- it is possible that each combination of modifications to the histone tails has a specific meaning. For a full explanation (fyi) see Alberts. (Or go to PubMed at , click on books on upper right, and enter 'histone code' in the search term box. )

3. What triggers the tightening or loosening process? Do TF's come first or remodeling/modification enzymes? Current Model

a. Regulatory TF's (activators) bind first -- that triggers remodeling, modification, etc. Loosens up the chromatin in the area to be transcribed.

b. Basal TF's bind later -- After chromatin is loosened up, basal TF's ( & possibly more regulatory TF's) can bind to the DNA, pol II can bind to the TF's, and transcription occurs.

4. How does this fit with the DNase sensitivity results?

a. Loosest -- Regions where transcription factors bind - - have nucleosomes removed &/or very loosened up = hypersensitive sites.

b. Looser -- Regions being transcribed -- have nucleosomes somehow "loosened up" or "remodeled" but not removed.

c. Loose -- Regions not being transcribed -- have regular nucleosomes ('loose', relative to heterochromatin, but 'tight' or 'not so loose' compared to transcribed euchromatin.) Regions that are not transcribed are often in euchromatin, not in heterochromatin.

II. Details of transcription in eukaryotes (as vs. prokaryotes) See Becker Ch 21, pp 660-664 (665-670).

A. More of everything needed for transcription in eukaryotes.

1. Multiple RNA Polymerases (see last lecture). We will focus on pol II (makes mRNA).

2. More proteins -- Need TF's, not just RNA pol.

3. More Regulatory Sequences -- many dif. ones bind dif. TF's

4. An Overview & Some terminology

  • Cis-acting regulatory element = affects only the nucleic acid molecule on which it occurs. Usually is a DNA sequence that binds some regulatory protein.

  • Trans-acting regulatory element = affects target nucleic sequences anywhere in the cell. The regulatory sequence codes for a regulatory molecule -- usually a protein -- that binds to a target -- usually a DNA sequence.

  • The term "trans acting" can be used to refer to the regulatory molecule (usually a protein) or to the DNA sequence that codes for it.

  • Cis acting elements = DNA itself = same in all cells of multicellular organism = target of trans acting regulatory molecules.

  • Trans acting regulatory molecules = product of DNA = TF's & other molecules = different in different cell types and at different times.

  • In euk. the number of different types of cis and trans acting control elements is much larger than in prokaryotes. What are they like? See below.

  • Regulation can be "+" or "-" depending on the function of the protein

  • Negative control -- If regulatory protein blocks transcription.

  • Positive control -- If regulatory protein enhances transcription.

  • Euk vs. Prok. -- Negative control (use of repressors) seems to be more common in prok. positive control (use of activators) more common in euk.

  • How you tell positive and negative control apart -- by effects of deletions.

B. Details of regulatory (cis acting) sites in the DNA. Prokaryotes have promoters and operators. What sequences do eukaryotes have in the DNA that affect transcription? (The following discussion refers mostly to regulation of transcription by RNA pol II. See texts esp. Becker for details about promoters etc. for pol I & III.) See Sadava Fig. 16.15 (14.14) or Becker fig.23-21 or handout 9A for structure of regulatory sites for a typical protein coding gene. Three types of regulatory sites:

1. Core Promoter

a. Numbering. Position of bases is usually counted along the sense strand from the start of transcription.

(1). "Start" = Point where transcription actually begins (usually marked with bent arrow) = zero.

(2). Upstream and Downstream

(a). Downstream = Going toward the 3' end on sense strand = in direction of transcription)

(b). Upstream = Going toward 5' end on sense strand = in opposite direction from transcription.

(3). Numbering -- some examples

(a). +10 = 10 bases downstream from start = 10 bases after start of transcription.

(b). -25 = 25 bases upstream from start = 25 bases before reaching start of transcription.

(c). +1 = first base in transcript one that gets a cap (modified base attached to 5' end).

(4). Numbering -- misc. features

(a). There is no 'zero' base, just as there is no 'zero' year between BC and AD and no zero hour between am and pm.

(b). In some cases, the position of bases is counted along the sense strand from the start of translation.If it is done this way, the A in the first AUG is +1. However, numbering is assumed to be from the start of transcriptionunless specified otherwise.

(c). TF's, RNA pol, etc. bind to grooves in double stranded DNA, not to one strand. However, positions in the DNA are usually specified in terms of the sense strand only. This does NOT mean that the protein binds only to the sense strand.

b. Core Promoter Itself Core promoter is defined by what you need to allow RNA polymerase to start in the right spot. What is included in it?

(1). Actual point for start of transcription (where bent arrow is) plus a few bases on either side of 'start.' Usually includes a few bases of the 5' UTR (untranslated region).

(2). Binding sites: Part where basal TF's and RNA polymerase binding starts -- usually section just upstream (before) start point. Often includes short sequence called a TATA box (usually about 25 bases before start point).

(3). Additional Features: Often includes some additional or different sequences besides those specified. Not all promoters of Pol II are the same. (If you are interested in details, see Becker 21-12b (13 b), or 23-21)

2. Proximal Control Elements. (Proximal = Near).

a. Location: Near core promoter and start of transcription usually "upstream" (on 5' side of start of transcription.) Usually includes regulator elements up to -100 or -200 (bases).

b. Terminology: Sometimes considered part of core promoter.

c. Function: Binding of appropriate proteins promotes or inhibits transcription. Identified by effects of deletions. Sequence and mechanism of action varies.

3. Distal Control Elements (Distal = Far)

a. Two kinds: Enhancers & silencers. These control elements can decrease (silencers) or increase transcription (enhancers).

b. These can be quite far from the gene they control (in either 5' or 3' direction = upstream or downstream). Can be in introns or in untranscribed regions.

c. These can work in both orientations -- Inverting them has no effect, unlike with promoters. See Becker fig. 23-22 (or handout 9B).

d. Mechanism of action -- bind TF's see below.

4. Terminology & Misc. Details -- this is for reference may not be discussed in class.

a. Boxes = short sequences that are found in regulatory regions (ex: TATA box)

b. Consensus sequences = sequence containing the most common base found at each position for all sequences of that type. Any individual version of sequence is likely to be different from the consensus at one or more positions. (Ex: TATAAAA = consensus sequence for TATA box. Means T is most common base in first position, A is most common in second position, etc.)

c. For multicellular organisms, term "operator" is not used for site/DNA sequence where a regulatory protein sits. Why? Because no polycistronic mRNA & no operons in higher eukaryotes. (Are some in unicellular euk.)

C. How do Basal Transcription Factors work?

1. Same in all cells. Needed to start transcription in all cells. See Sadava fig. 16.14 (14.13) (14.12) or Becker fig. 21-13 (21-14).

2. Properties

a. Many basal TF's needed.

b. Basal TF's for RNA pol. II .

(1). Terminology: Basal TF's for pol II are called TFIIA, TFIIB, etc.

(2). Major one is TFIID it itself has many subunits. Most studied subunit is TBP (TATA binding protein -- See Becker fig. 21-14 (21-15).) Recognizes TATA box when there is one.

(3). Other polymerases have TF's too, but TF's for pol II are of major interest, since pol II → mRNA

c. Basal TF's bind first to core promoter, and then RNA pol binds to them. Takes a lot of proteins to get started. RNA polymerase does not bind directly to the DNA.

D. How do Regulatory or Tissue Specific TF's Work?

1. Different ones are used in different cell types or at certain times. Not all are needed in all cells. See Becker fig. 23-24.

2. Properties

a. Bind to areas outside the core promoter -- usually to enhancers or silencers (distal control elements) but sometimes to proximal control elements

b. When regulatory TF's bind, can decrease or promote transcription.

(1). Activators. TF's called activators if bind to enhancers and/or increase transcription.

(2). Repressors.TF's called repressors if bind to silencers and/or decrease transcription.

c. How regulatory TF's affect transcription: DNA thought to loop around so silencer/enhancer is close to core promoter. TF's on enhancer help stabilize (or block) binding of basal TF's directly or indirectly to core promoter. (See Becker fig. 23-23 or Sadava fig. 16.15 (14.14) and section on regulatory TF's below.)

d. Euk. vs Prok. repressors -- both 'repressors' interfere with transcription, but mechanism of action is different.

e. Role of Co-activators -- Proteins that bind to TF's on the enhancer and influence transcription (but don't bind directly to the DNA) are often called co-activator (or co-repressor) proteins. There are 2 ways co-activators affect transcription:

(1). Act as mediator -- Connect two parts of the transcription machine. One part of mediator binds to TF (which is bound to enhancer or silencer) and other part of mediator binds to basal transcription factors (or pol II) on core promoter and/or proximal control elements. Mediator = usual name of complex of co-activators that act this way.

(2). Modify state of chromatin. Bind to TF on enhancer and loosen up chromatin in gene to be transcribed. Remodeling proteins and histone modifying enzymes are included in this category.

To review gene structure & TF's, try problems 4R-2, 4R-5A & 4R6-A.

f. Co-ordinate control. A group of genes can all be turned on or off at once in response to the same signal (heat shock, hormone, etc.).

(1). Prokaryotes vs. Eukaryotes: Both prok. and euk. exhibit co-ordinate control, but mechanism is different. (See table below.)

(2). Location of coordinately controlled genes

(a). In prokaryotes, coordinately controlled genes are located together in operons.

(b). In eukaryotes, coordinately controlled genes do not need to be near each other -- they just have to have the same (cis acting) control elements. See Sadava fig. 16.17 (14.16).

(3). Control elements:

(a). All genes turned on in the same cell type and/or under the same conditions share the same control elements -- therefore these genes all respond to the same regulatory TF's. Result is multiple mRNA's, all made in response to same signal (s).

(b). Most genes have multiple (cis acting) control elements. Therefore transcription of most genes is affected by more than one TF.

(c). Transcription of any particular gene depends on the combinations of TF's, not just one, available in that cell type.

(4). Differences in TF's. Different cell types make different regulatory TF's. Therefore different groups of coordinately controlled genes are turned on/off. See Becker fig. 23-24.

(5). Comparison of situation in prokaryotes vs multicellular eukaryotes:

Chapter 27 - Prokaryotes

  • If humans were to disappear from the planet tomorrow, life on Earth would go on for most other species.
  • But prokaryotes are so important to the biosphere that if they were to disappear, the prospects for any other life surviving would be dim.

Prokaryotes are indispensable links in the recycling of chemical elements in ecosystems.

  • The atoms that make up the organic molecules in all living things were at one time part of inorganic compounds in the soil, air, and water.
  • Life depends on the recycling of chemical elements between the biological and chemical components of ecosystems.
    • Prokaryotes play an important role in this process.
    • Chemoheterotrophic prokaryotes function as decomposers, breaking down corpses, dead vegetation, and waste products and unlocking supplies of carbon, nitrogen, and other elements essential for life.
    • Prokaryotes also mediate the return of elements from the nonliving components of the environment to the pool of organic compounds.
    • Autotrophic prokaryotes use carbon dioxide to make organic compounds, which are then passed up through food chains.
    • They are the only organisms able to metabolize inorganic molecules containing elements such as iron, sulfur, nitrogen, and hydrogen.
    • Cyanobacteria not only synthesize food and restore oxygen to the atmosphere, but they also fix nitrogen.
      • This stocks the soil and water with nitrogenous compounds that other organisms can use to make proteins.

      Many prokaryotes are symbiotic.

      • Prokaryotes often interact with other species of prokaryotes or eukaryotes with complementary metabolisms.
      • An ecological relationship between organisms that are in direct contact is called symbiosis.
        • If one of the symbiotic organisms is larger than the other, it is termed the host, and the smaller is known as the symbiont.
        • Many of these species are mutualists, digesting food that our own intestines cannot.
        • The genome includes a large array of genes involved in synthesizing carbohydrates, vitamins, and other nutrients needed by humans.
        • Signals from the bacterium activate human genes that build the network of intestinal blood vessels necessary to absorb food.
        • Other signals induce human cells to produce antimicrobial compounds to which B. thetaiotaomicron is not susceptible, protecting the bacterium from its competitors.

        Concept 27.5 Prokaryotes have both harmful and beneficial impacts on humans

        • Pathogenic prokaryotes represent only a small fraction of prokaryotic species.
          • Other prokaryotes serve as essential tools in agriculture and industry.
          • If untreated, Lyme disease can lead to debilitating arthritis, heart disease, and nervous disorders.
          • An exotoxin produced by Vibrio cholerae causes cholera, a serious disease characterized by severe diarrhea.
            • The exotoxin stimulates intestinal cells to release chloride ions (Cl?) into the gut water follows by osmosis.
            • The endotoxin-producing bacteria in the genus Salmonella are not normally present in healthy animals.
            • Salmonella typhi causes typhoid fever.
            • Other Salmonella species, including some that are common in poultry, cause food poisoning.
            • E. coli is ordinarily a harmless symbiont in the human intestines.
            • Pathogenic strains causing bloody diarrhea have arisen.
              • One of the most dangerous strains is called O157:H7.
              • Today, it is a global threat, with 75,000 cases annually in the United States alone.
              • In 2001, an international team of scientists sequenced the genome of O157:H7 and compared it with the genome of a harmless strain of E. coli.
              • 1,387 of the 5,416 genes in O157:H7 have no counterpart in the harmless strain.
              • These 1,387 genes must have been incorporated into the genome of O157:H7 through horizontal gene transfer, most likely through the action of bacteriophages.
              • Many of the imported genes are associated with the pathogen’s invasion of its host.
              • For example, some genes code for exotoxins that enable O157:H7 to attach itself to the intestinal wall and extract nutrients.

              Humans use prokaryotes in research and technology.

              • Humans have learned to exploit the diverse metabolic capabilities of prokaryotes for scientific research and for practical purposes.
                • Much of what we know about metabolism and molecular biology has been learned using prokaryotes, especially E. coli, as simple model systems.
                • Increasingly, prokaryotes are used to solve environmental problems.
                • The most familiar example is the use of prokaryote decomposers to treat human sewage.
                • Anaerobic bacteria decompose the organic matter into sludge (solid matter in sewage), while aerobic microbes do the same to liquid wastes.
                • Other bioremediation applications include breaking down radioactive waste and cleaning up oil spills.
                • Other prokaryotes can extract gold from ore.

                ecture Outline for Campbell/Reece Biology, 7th Edition, © Pearson Education, Inc. 27-1

                Chloroplasts and photosynthetic eukaryotes

                The information below was adapted from OpenStax Biology 23.1

                Some groups of eukaryotes are photosynthetic. Their cells contain, in addition to the “standard” eukaryotic organelles, photosynthetic organelles called chloroplasts. Like mitochondria, chloroplasts appear to have an endosymbiotic origin. Chloroplasts are derived from cyanobacteria that lived inside the cells of an ancestral, aerobic, heterotrophic eukaryote. Evidence suggests that engulfment of a cyanobacteria-like organism has happened twice in the history of eukaryotes: in one case, the common ancestor of the major lineage/supergroup Archaeplastida took on a cyanobacterial endosymbiont in the other, the ancestor of the small amoeboid rhizarian taxon, Paulinella, took on a different cyanobacterial endosymbiont. Almost all photosynthetic eukaryotes are descended from the first event, and only a couple of species are derived from the other.

                The Similarities

                There are many other cell types in different forms, like neurons, epithelial, muscle cells, etc. But prokaryotes and eukaryotes are the only true cell structures and types. The following points will cover the main similarities.

                • The genetic material, i.e., presence of DNA is common between the two cells.
                • The presence of RNA is common.
                • They both have a cell membrane covering them.
                • Resemblances are seen in their basic chemical structures. Both are made up of carbohydrates, proteins, nucleic acid, minerals, fats, and vitamins.
                • Both of them have ribosomes, which make proteins.
                • They regulate the flow of nutrients and waste matter that enters and exits the cellules.
                • Basic life processes like photosynthesis and reproduction are carried out by them.
                • They need energy supply to survive.
                • They both have ‘chemical noses’ that keep them updated and aware of all the reactions that occur within them and in the surrounding environment.
                • Both these organisms have a fluid-like matrix called the cytoplasm that fills the cells.
                • Both have a cytoskeleton within the cell to support them.
                • They have a thin extension of the plasma membrane which is supported by the cytoskeleton.
                • Flagella and cilia are found in eukaryotes likewise endoflagella, fimbriae, pili and flagella are found in prokaryotes. They are used for motility and adhering to surfaces or moving matter outside the cells.
                • Some prokaryotic and eukaryotic cellules have glycocalyces as a common material. This is a sugar-based structure that is sticky and helps the cells in anchoring to each other thus, giving them some protection.
                • They have a lipid bilayer, known as the plasma layer, that forms the boundary between the inner and outer side of the cell.

                There are many differences between them, of which age and structure are the main attributes. It is believed by scientists that eukaryotic cells evolved from prokaryotic cells. In short, both are the smallest units of life.

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