Difference between eukaryotic and prokaryotic genome

Genomes of prokaryotes
Genomes of eukaryotes

1. Difference between prokaryotic and eukaryotic genome

2. Genome Prokaryotes Eukaryotes Single, Circular Multiple, Linear

3. Location of genome Prokaryotes Eukaryotes Cytoplasm Haploid or merodiploid Plasmids are commonly found More compact Telomers are absent Introns are absent Repetitive DNA absent Transcription and translation occur simultaneously Inside the nucleus Diploid Plasmids are not observed Less compact Telomers are present Introns are present Repetitive DNA present Transcription takes place in nucleus and translation occur in the cytoplasm

4. Ratio of genomic to non genomic DNA Prokaryotes Eukaryotes Over 90 % protein coding genes, little nongenetic DNA , no pseudogenes almost no repeats Horizontal gene transfer Homologous recombination and chromosome, up to 5-10 % protein coding genes, abundance of nongenetic DNA-pseudogenes, and different repeats segregation linked to reproduction

5. Cell division Prokaryotes Eukaryotes No mitosis or meiosis Binary fission or budding Evolution is based on the rapid proliferation and accumulation of mutations and hypermutations Mitosis and meiosis occur in cells High contents of repeats facilitates the recombination's, translocations, shuffling's, duplications, and rearrangements of different scales

6. Sexual reproduction and crossing over Prokaryotes Eukaryotes True sexual reproduction is absent Through conjugation genetic material is transmitted to another organism May have pili and fimbriae No histone proteins are found Lack cytoskeleton Trans acting elements absent Distal acting elements absent True sexual reproduction is present and male and female participation is equal May have cilia DNA is wound around the histone proteins Cytoskeleton made of actin and microtubules Trans acting elements are present Distal acting elements are present

7. Flagella Prokaryotes Eukaryotes Have simple structure with 9 +0 arrangement Flagellin protein Have complex structure and have 9+2 arrangement of microfibrils

8. Cell wall Prokaryotes Eukaryotes Bacterial cell wall – peptidoglycan Plant cell wall- cellulose Animals – lack cell wall Fungi- chitin, cellulose

9. Cell organelles Prokaryotes Eukaryotes Membrane bound organelles such as endoplasmic reticulum, Golgi complex, mitochondria, chloroplasts and vacuoles are absent Ribosomes 70S Membrane bound organelles such as endoplasmic reticulum, Golgi complex, mitochondria, chloroplasts, vacuoles are present Ribosomes 80 and 70S

10. All cellular activities are encoded within a cell’s DNA. The sequence of bases within a DNA molecule represents the genetic information of the cell. Segments of DNA molecules are called  genes , and individual genes contain the instructional code necessary for synthesizing various proteins, enzymes, or stable RNA molecules. The full collection of genes that a cell contains within its genome is called its  genotype . However, a cell does not express all of its genes simultaneously. Instead, it turns on (expresses) or turns off certain genes when necessary. 

11. The set of genes being expressed at any given point in time determines the cell’s activities and its observable characteristics, referred to as its  phenotype .  Genes that are always expressed are known as  constitutive genes ; some constitutive genes are known as  housekeeping genes  because they are necessary for the basic functions of the cell. While the genotype of a cell remains constant, the phenotype may change in response to environmental signals (e.g., changes in temperature or nutrient availability) that affect which nonconstitutive genes are expressed.

12. For example, the oral bacterium  Streptococcus mutans  produces a sticky slime layer that allows it to adhere to teeth, forming  dental plaque ; however, the genes that control the production of the slime layer are only expressed in the presence of sucrose (table sugar). Thus, while the genotype of  S. mutans  is constant, its phenotype changes depending on the presence and absence of sugar in its environment. Temperature can also regulate  gene expression . For example, the gram-negative bacterium  Serratia marcescens , a pathogen frequently associated with hospital-acquired infections, produces a red pigment at 28 °C but not at 37 °C, the normal internal temperature of the human body

13. Mechanisms if control of genes in bacteria Bacteria have very simple general mechanisms for coordinating and regulation of genes that encode products involved in a set of related process The gene cluster and promoter plus additional sequences that function together are called an operon