Biology

Difference Between Prokaryotic Chromosome and Eukaryotic Chromosome

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Main Difference

The main difference between Prokaryotic Chromosome and Eukaryotic Chromosome is that Prokaryotic Chromosome is referring to as a short, circular molecule of DNA, whereas Eukaryotic Chromosome is referring as an elongated, linear molecule.

Prokaryotic Chromosome vs. Eukaryotic Chromosome

The prokaryotic chromosome is considered as a double-stranded circular molecule of DNA that is present in prokaryotes whereas, the eukaryotic chromosome is considered as a molecule having long strands of DNA having genetic information and present in eukaryotes. The prokaryotic chromosome is made up of only a single chromosome, whereas; eukaryotic chromosomes made up of several chromosomes.

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The occurrence of the prokaryotic chromosome is primarily in the nucleoid, while the presence of a eukaryotic chromosome is mainly inside the nucleus. No homologous chromosomes are present in the prokaryotic chromosome because they are haploid; in contrast, a pairing of homologous chromosomes is present in the eukaryotic chromosome.

A prokaryotic chromosome is generally attached to the cytoplasm from the inside, while the eukaryotic chromosome does not have any contact or attachment with the cytoplasm. The general structure of the prokaryotic chromosome is a short and circular DNA molecule, whereas, the general structure of the eukaryotic chromosome is a long or extended, linear molecule of DNA.

Telomeres and centromeres are primarily not present in the prokaryotic chromosome; on the flip side, the eukaryotic chromosome consists of centromere and telomeres. The prokaryotic chromosome is usually linked with nucleoid-associated proteins, which helps them for packing, while by associating with histone proteins, the eukaryotic chromosome forms unique structures known as nucleosomes.

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The prokaryotic chromosome consists of the single origin of their replication usually per chromosome; however, the eukaryotic chromosome consists of many origins of their replication, usually per chromosome.

Comparison Chart

Prokaryotic ChromosomeEukaryotic Chromosome
The prokaryotic chromosome contains a simple structure and is characterized by double-stranded DNA. They are linked with specific proteins other than histone proteins, which helps them in stabilizing their supercoiled domains.The eukaryotic chromosome contains a complex structure because it consists of more than just one DNA, and their DNA consist of a large number of histone proteins wrapped around DNA molecule, forming a particular structure known as a nucleosome.
Considered As
Considered as a double-stranded circular molecule of DNA which is present in prokaryotesConsidered as a molecule having long strands of DNA having genetic information and present in eukaryotes
Number
Made up by only a single chromosomeMade up by several chromosomes
Homologous Chromosomes
No homologous chromosomes are present because they are haploidA pairing of the homologous chromosome is present because they are diploid
Attachment to the Cytoplasm
Generally attached with the cytoplasm from the insideDoes not have any contact or attachment with the cytoplasm
General Structure
The general structure is short, and have a circular DNA moleculeThe general structure is long or extended, and have a linear molecule of DNA
Telomeres/ Centromeres
Telomeres and centromeres are primarily not presentConsist of centromere and telomeres
Association with Proteins
Usually linked with nucleoid-associated proteins which helps them for packingBy associating with histone proteins, the eukaryotic chromosome form special structures known as nucleosomes
DNA Replication
The replication of DNA happens typically at the start of the cell divisionThe DNA replication happens during the S phase of the cell
Origin of Replication
Consist of a sole origin of their replication usually per chromosomeConsist of many origins of their replication usually per chromosome
Gene Structure
The prokaryotic gene structure is organized into operons.The eukaryotic gene structure is regulated like individual structures.
Number of Proteins
Encrypt for a few proteinsEncrypted for a large number of chromosomes
Genetic Recombination
Get genetic recombination by horizontal gene transfer.Get genetic recombination by the process of fusion of gametes or through the meiosis.
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What is the Prokaryotic Chromosome?

The genetic material of prokaryotes (bacteria) is known as the prokaryotic chromosome. They form the whole DNA pool in prokaryotes besides with plasmid DNA. Furthermore, a single prokaryotic chromosome is present only in one cell in prokaryotes.

The prokaryotic chromosome is a covalently closed circular DNA (cccDNA) molecule which size may vary from 0.16-12.2 million base pairs. The DNA molecule of prokaryotes is not surrounded by nuclear membranes, so it consists of an association with the cytoplasm, and it mainly occurs in the nucleoid of the cell. Besides, the looped structures for packing which are formed in prokaryotic chromosomes due to the help of nucleoid-associated proteins.

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The gene structure of the prokaryotic chromosome is organized into operons. Each operon consists of functionally-related genes, which are usually expressed together.

What is the Eukaryotic Chromosome?

The genetic material of eukaryotes is known as a eukaryotic chromosome. The eukaryotic chromosomes are wholly surrounded by two nuclear membranes and producing organelle known as the nucleus. Besides, a single eukaryotic cell consists of 10-50 eukaryotic chromosomes, and these are structurally linear molecules.

The size of a human genome is considered around 3 billion base pairs. The center of the eukaryotic chromosome is known as centromere, and the two ends are known as telomeres. The eukaryotic chromosome is associated with a particular type of proteins known as histone proteins, which form the dense packing around the eukaryotic DNA by forming tight coils.

The eukaryotic chromosome consists of many origins of their replication, usually per chromosome, hence forming the multiple replication forks and bubbles per chromosome. This method is slow, and its proportion is 100 base pairs in one second.

Key Differences

  1. In the prokaryotic chromosome, the prokaryotic DNA is referred to as the circular double-stranded molecule, and the prokaryotic chromosome is relatively small in size; on the other hand, in the eukaryotic chromosome, the eukaryotic DNA is referred to as the long, double-stranded DNA molecule.
  2. In the prokaryotic chromosome, the typical formation of the chromosome is generally absent, whereas, in the eukaryotic chromosome, the formation of the chromosome is organized as discrete structural units.
  3. A single chromosome is present per cell in the prokaryotic chromosome; on the flip side, in the eukaryotic chromosome, generally from two to many chromosomes are present.
  4. The length of the prokaryotic chromosome is comparatively shorter, while the length of the eukaryotic chromosome is relatively more extensive than that of prokaryotes.
  5. The prokaryotic chromosome consists of covalently bonded closed circular DNA; on the other hand, the eukaryotic chromosome consists of a linear DNA having two ends.
  6. The prokaryotic chromosome is encoded for only a few proteins other than histone proteins, while the eukaryotic chromosome is encoded for a large number of proteins such as histone proteins.
  7. The prokaryotic chromosome is present freely in the middle of the cell, and it is not surrounded by the nucleus; at the same time, the eukaryotic chromosome is always enclosed or surrounded by the nucleus.
  8. The prokaryotic chromosome mainly stays linked with cytoplasm due to the absence of the nuclear membrane; in contrast, the eukaryotic chromosome is separated from the cytoplasm and does not have any association with the cytoplasm due to the presence of the nuclear membrane.

Conclusion

A prokaryotic chromosome is a short circular DNA molecule and has a single origin of their replication; in contrast, the eukaryotic chromosome is extended, a linear molecule of DNA that is densely packed with a large number of histone proteins.

Janet White

Janet White is a writer and blogger for Difference Wiki since 2015. She has a master's degree in science and medical journalism from Boston University. Apart from work, she enjoys exercising, reading, and spending time with her friends and family. Connect with her on Twitter @Janet__White

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