Eukaryotic Vs Prokaryotic Cells – Cell Biology

    Eukaryotic Vs Prokaryotic Cells – Cell Biology, Right now, talk about the similarities and contrasts between the eukaryotic cells of your body and prokaryotic cells in bacteria. Eukaryotes sort out various capacities inside particular film bound compartments called organelles. These structures don’t exist in prokaryotes.

    Prokaryote = without a nucleus | Eukaryote = with a nucleus

    Prokaryotic and Eukaryotic Cells

    Your body’s made out of trillions of cells – loads of various kinds of cells that make up various organs and different pieces of your body. Your body is likewise where multiple times that number of microscopic organisms call ‘ah, it feels good to be back home.’ But, don’t be apprehensive – these microbes accomplish more great than damage to you. What’s more, just on the off chance that you needed to start up a discussion with your occupants, you and your microorganisms do share a couple of things practically speaking.

    All cells share some normal attributes that make them living things. All living beings are made out of cells, the essential thing unit of life. They contain DNA as a heritable hereditary material, and they can replicate. They interpret DNA into RNA and make an interpretation of RNA into proteins on ribosomes. They can likewise manage transport over a cell film and require compound vitality for some cell forms.

    The main greatest contrast between the microorganisms in your body and the phones making up your body are these minor cell parts called organelles. You’ve really taken in a great deal about organelles in different exercises without knowing it. Organelles are just layered bound compartments inside a cell, for example, the core, mitochondria, chloroplasts, Golgi, and endoplasmic reticulum.

    You are a eukaryote. Your cells are eukaryotic. Eukaryotic cells contain layer bound organelles, including a core. Eukaryotes can be single-celled or multi-celled, for example, you, me, plants, growths, and bugs.

    Microscopic organisms are a case of prokaryotes. Prokaryotic cells don’t contain a core or some other layer bound organelle. Prokaryotes incorporate two gatherings: microbes and another gathering called archaea.

    Having organelles is a serious deal for a cell. A microscopic organism’s cell gets along fine and dandy without organelles, however, microorganisms are modest. That is the reason we’re ready to have such a significant number of them in our bodies without truly seeing them.

    Our cells, however – they’re still little to the unaided eye, yet they’re tremendous in contrast with microbes. Our eukaryotic cells are greater in size, with considerably more DNA. More DNA implies more interpretation, and more translation implies more interpretation, and more interpretation implies more proteins. Greater cells make the requirement for organelles.

    You can consider it along these lines. In the event that you just had two sets of shoes and a couple of straightforward outfits, you could simply hang up your outfits and put your shoes on the floor inside a little storage room. Straightforward. Nonetheless, suppose you have shopping enslavement, and you have seven unique sets of dark jeans, ten sets of shoes in totally various shades of darker (and different hues, obviously), and you barely ever wear a similar cap twice. You can envision that you would require a stroll in the storeroom, complete with racking frameworks to compose everything, correct?

    All things considered, organelles are a productive method to sort out everything that is going on in the cell – to compartmentalize cell capacities. That is actually what a eukaryotic cell is doing – isolating cell forms and sorting out its space. Be that as it may, don’t be tricked by the ‘straightforwardness’ of prokaryotes. Their littler size and straightforwardness is a preferred position to their way of life.

    Check out the differences!!

    Prokaryotic Cells Eukaryotic cells
    small cells (< 5 mm) larger cells (> 10 mm)
    always unicellular often multicellular
    no nucleus or any membrane-bound organelles always have a nucleus and other membrane-bound organelles
    DNA is circular, without proteins DNA is linear and associated with proteins to form chromatin
    ribosomes are small (the 70S) ribosomes are large (the 80S)
    no cytoskeleton always has a cytoskeleton
    cell division is by binary fission cell division is by mitosis or meiosis
    reproduction is always asexual reproduction is asexual or sexual

    Let’s start with the basics!!


    A sequence of three bases in tRNA that is complementary to a codon in mRNA. Enables tRNA to sequence amino acids in the order specified by mRNA.


    A non-sex chromosome. Synonymous with somatic chromosomes (chromosome pairs 1-22).


    Rod-shaped structures within the cell nucleus that carry genes encoded by DNA.

    Cis position

    Genes in the cis position are on the same chromosome of a pair of homologous chromosomes.

    Cloned gene

    A recombinant DNA molecule with the gene of interest.


    Genes are co-dominant if both alleles are expressed in the heterozygous state, e.g., K and k genes


    A sequence of three bases in DNA or RNA that codes for a single amino acid. Enables specific proteins to be made by specific genes.

    Crossing over

    The exchange of genetic material between members of a pair of homologous chromosomes.


    An abnormality in which part of a chromosome (carrying genetic material) is lost.

    The diploid number of chromosomes

    The number of chromosomes found in somatic cells, which in humans is 46.


    Deoxyribonucleic acid. Composed of nucleic acids, these molecules encode the genes that allow genetic information to be passed to offsprings.

    DNA polymerases

    Enzymes that can synthesize new DNA strands using previously synthesized DNA (or RNA) as a template.

    DNA probe

    A cloned DNA molecule labeled with a radioactive isotope (e.g., 32P or 35S) or a nonisotopic label (e.g. biotin). Used in molecular genetics to identify complementary DNA sequences by hybridizing them.

    Dominant gene

    A gene is dominant if it is expressed when heterozygous but its allele is not.

    Functional genes

    Genes that produce proteins, e.g., blood group genes that produce antigens.


    A segment of a DNA molecule that codes for the synthesis of a single polypeptide.

    Gene interaction

    The situation in which genes inherited at different loci.


    A term used to denote the entire DNA sequence (gene content) of a gamete, person, population, or species.

    Homologous chromosomes

    A matched pair of chromosomes, one from each parent.


    Genes are linked if they are on the same chromosome within a measurable distance of each other and are normally inherited together.


    The location of allelic genes on the chromosome. (Plural = loci)

    Messenger RNA (mRNA)

    Type of RNA polymerase using DNA as a template. It contains the codons that encompass the genetic codes to be translated into protein.

    Nucleic acids

    Polymers of phosphorylated nucleosides, the building blocks of DNA and RNA.


    The building blocks of RNA and DNA. Compounds consisting of a purine (adenine or guanine) or pyrimidine (thymine or cytosine) attached to a ribose (in RNA) or deoxyribose (in DNA) at the 11 carbon.


    A short sequence of nucleotides that controls the adjacent structural (functional) genes.


    A postulated unit of gene action that consists of an operator and the closely linked functional genes it controls.


    Extrachromosomal circular DNA in bacteria. Plasmids can independently replicate and encode a product for drug resistance or some other advantage. Used in molecular genetics as vectors for cloned segments of DNA.

    Reverse transcriptase

    An RNA-dependent DNA polymerase that synthesizes DNA from an RNA template. Used by retroviruses like the human immunodeficiency virus (HIV) to make proviral DNA from its RNA genome.


    Synthesis of single-stranded RNA by RNA polymerase using DNA as a template.

    Restriction fragment length polymorphisms (RFLP)

    Regions of DNA of varying lengths that can be cut out of DNA by restriction endonucleases. Because the fragment lengths vary among individuals, they are polymorphic and can be used as genetic markers.


    The process of translating the codon sequence in mRNA into polypeptides with the help of tRNA and ribosomes.

    Eukaryotic and prokaryotic genome


    • The word “genome,” coined by German botanist Hans Winkler in 1920, was derived simply by combining gene and the final chromosome.
    • An organism’s genome is defined as the complete haploid genetic complement of a typical cell.
    • In diploid organisms, sequence variations exist between the two copies of each chromosome present in a cell.
    • The genome is the ultimate source of information about an organism.
    • The number of genomes sequenced in their entirety is now in the thousands and includes organisms ranging from bacteria to mammals.
    • The first complete genome to be sequenced was that of the bacterium Haemophilus influenzae, in 1995.
    • The first eukaryotic genome sequence, that of the yeast Saccharomyces cerevisiae, followed in 1996.
    • The genome sequence for the bacterium Escherichia coli became available in 1997.
    • The much larger effort directed at the human genome was also accelerating.

    Bacterial genome

    • Bacterial genomics can give us a broader understanding of how bacteria functions, bacterias origins, and what bacteria live in our world that we can study by their DNA.
    • Of medical interest, bacterial genomics is also anticipated to play a significant role in speeding up the development of better therapies and vaccines for controlling disease-causing bacteria.
    • It will also be the cornerstone of anticipated DNA- based diagnostic tools that will hopefully enable doctors to make quicker, more accurate diagnoses of infectious disease.
    • The size of Bacterial chromosomes ranges from 0.6 Mbp to over 10 Mbp •The smallest Bacterial genome identified thus far is from Mycoplasma genitalium, an obligate intracellular pathogen with a genome size of 0.58 Mbp (580 Kbp).
    • M. genitalium is restricted to the intracellular niche because it lacks genes encoding enzymes required for amino acid biosynthesis and the peptidoglycan cell wall, genes encoding TCA cycle enzymes, and many other biosynthetic genes.
    • In contrast to such obligate intracellular bacteria, free-living bacteria must dedicate many genes toward the biosynthesis and transport of nutrients and building blocks.
    • The smallest free-living organisms have a genome size of over 1 Mbp.
    • Currently, the largest sequenced prokaryotic genome is streptomyces coelicolor, 8.7 Mbp.


    • The genome of E.coli contains amount of 4X106 base pairs
    • > 90% of DNA encodes a protein
    • Lacks a membrane-bound nucleus.
    • Circular DNA and supercoiled domain
    • Histones not present
    • Prokaryotic genomes generally contain one large circular piece of DNA referred to as a “chromosome” (not a true chromosome in the eukaryotic sense).
    • Some bacteria have linear “chromosomes”
    • Many bacteria have small circular DNA structures called plasmids which can be swapped between neighbors and across bacterial species.


    • The term plasmid was first introduced by the American molecular biologist Joshua Lederberg in 1952.
    • A plasmid is separate from and can replicate independently of the chromosomal DNA.
    • Plasmid size varies from 1 to over 1,000 (kbp).


    ØThe genome of yeast cells contains

    • 1.35×107 base pairs
    • A small fraction of the total DNA encodes protein.
    • Many repeats of non-coding sequences
    • All chromosomes are contained in a membrane-bound nucleus
    • DNA is divided between two or more chromosomes
    • A set of five histones
    • DNA packaging and gene expression regulation


    • The study of chromosomes, their structure, and their inheritance are known as Cytogenetics.
    • Each species has a characteristic number of chromosomes and this is known as a karyotype.

    DNA Supercoiling

    • One way prokaryotes compress their DNA into smaller spaces is through supercoiling.
    • Genomes can be negatively supercoiled, meaning that the DNA is twisted in the opposite direction of the double helix, or positively supercoiled, meaning that the DNA is twisted in the same direction as the double helix.
    • Most bacterial genomes are negatively supercoiled during normal growth.
    DNA Supercoiling
    • Multiple proteins act together to fold and condense prokaryotic DNA.
    • In particular, one protein called HU, which is the most abundant protein in the nucleoid, works with an enzyme called topoisomerase I to bind DNA and introduce sharp bends in the chromosome, generating the tension necessary for negative supercoiling.
    • Integration host factor (IHF), can bind to specific sequences within the genome and introduce additional bends.
    • The folded DNA is then organized into a variety of conformations that are supercoiled and wound around tetramers of the HU protein, much like eukaryotic chromosomes are wrapped around histones.
    • Once the prokaryotic genome has been condensed, DNA topoisomerase I, DNA gyrase, and other proteins help maintain the supercoils.
    • It has been determined that prokaryotic DNA replication occurs at a rate of 1,000 nucleotides per second, and prokaryotic transcription occurs at a rate of about 40 nucleotides per second.
    • During transcription, small regions of the chromosome can be seen to project from the nucleoid into the cytoplasm.
    • Because there is no nuclear membrane to separate prokaryotic DNA from the ribosomes within the cytoplasm, transcription and translation occur simultaneously in these organisms.


    • When different genes are to be expressed in exactly the same amount because they are part of a complex, transcription of all genes in a single transcript diminishes gene expression.
    • Pairs of divergently oriented operons show correlated expression levels this is because sometimes they share bidirectional regulatory regions that allow co-regulation of the two operons.

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    Rajat Singh
    Rajat Singh is the Editor-in-chief at Bioinformatics India, he is a Master's in Bioinformatics and validates all the data present on this website. Independent of his academic qualifications he is a marketing geek and loves to explore trends in SEO, Keyword research, Web design & UI/UX improvement.

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