Prokaryotic vs Eukaryotic Chromosome
Prokaryotes and Eukaryotes are the two major domains of living organisms. This classification is on the basis of the features of their cellular features primarily the nature of membrane bounded organelles and organization of the genetic materials. Both prokaryotes and eukaryotes contain the genetic materials which are organized into specialized structures called Chromosomes. Even though the term chromosome is accurate only for eukaryotes, the genetic materials of prokaryotes are also described as prokaryotic chromosome. The prokaryotic chromosome is considerably different from that of eukaryotes.
The present post describes the Similarities and Differences between the Prokaryotic Chromosome and Eukaryotic Chromosome with the help of a Comparison Table.
Similarities between Prokaryotic and Eukaryotic Chromosomes
Ø The chromosome of both prokaryotes and eukaryotes contains the genetic material DNA.
Ø The chemical composition and structural organization of DNA is similar in both prokaryotes and eukaryotes.
Ø In both prokaryotes and eukaryotes, the expression of genetic material is facilitated by transcription and translation.
Ø In both groups, the negatively charged DNA interacts with some positively charged proteins to nullify their charges.
Ø The genetic material contains both coding and noncoding sequences.
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Ø In both groups, the methylation of DNA in the chromosome causes its inactivation.
Ø Both groups contain extra-chromosomal genetic materials. (plasmids in prokaryotes and DNA of mitochondria and chloroplasts in eukaryotes)
Difference between Prokaryotic and Eukaryotic Chromosomes
Sl. No. Prokaryotic Chromosome Eukaryotic Chromosome 1 The typical chromosome formation is absent in prokaryotes. In eukaryotes, the genetic material is organized as distinct structural entities called the Chromosomes. 2 Only a single chromosome per cell Always two to many chromosomes per cell. 3 The prokaryotic chromosome is comparatively shorter Eukaryotic chromosomes are larger than that of prokaryotes. 4 Prokaryotic chromosome contains a covalently closed circular DNA (cccDNA). Each eukaryotic chromosome contains a linear DNA with two ends. 5 Prokaryotic chromosomes codes for few proteins. Codes for a large number of proteins. 6 Chromosome occupies freely in the center of the cell and not covered by the nucleus. Chromosomes are always enclosed in the nucleus. 7 Due to the absence of nucleus, the prokaryotic chromosomes stay in direct contact with the cytoplasm. Eukaryotic chromosomes are separated from the cytoplasm by the nuclear membrane. 8 Prokaryotic chromosome sometimes associated with the mesosomes of the plasma membrane. Eukaryotic chromosome cannot be associated with the plasma membrane. They always stay away from the plasma membrane. 9 The DNA is not associated with histone proteins in prokaryotic chromosomes. DNA is associated with histone proteins in eukaryotes. 10 Nucleosomes are not formed in prokaryotes. In eukaryotes, the association of DNA with the histone produces distinct structural repeats called nucleosomes. 11 Prokaryotic chromosome contains only a single origin of replication (Ori). Eukaryotic chromosome contains many origin or replications. 12 In prokaryotes, the replication of DNA can occur at any stage of the life cycle. In eukaryotes, the genetic material will only replicate at the S phase of cell cycle. 13 The negative charge of prokaryotic chromosomes are nullified by Mg2+ ions The negative charge of the eukaryotic DNA is nullified by histone proteins (positively charged). 14 Telomere is absent since the chromosome is circular. Telomere is present in the tip of eukaryotic chromosomes. 15 Structures like centromere, Kinetochore, secondary constriction and chromosomal arms are not formed in prokaryotic chromosomes. Eukaryotic chromosomes contain centromere, kinetochore and chromosomal arms.
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