Organisation of DNA - Prokaryotes

Organisation of DNA - Prokaryotes

Bacteria: The Prokaryotic Organisms

• Bacteria are a type of prokaryotic organism.
• Unlike eukaryotic cells, they lack a membrane-bound nucleus.
• In bacteria, DNA is not enclosed within a nucleus but exists freely in the cytoplasm.

Single Circular Chromosome

• Bacterial DNA is organised as a single circular chromosome.
• This chromosome holds all the genes necessary for the bacterium's survival and functioning.
• The circular arrangement of DNA is located at the centre of the bacterial cell.

Plasmids: Extra DNA Circles

• In addition to the main chromosome, bacteria also possess extra circles of DNA known as plasmids.
• Plasmids contain additional genes that are not essential for basic survival but can provide advantages to the bacterium.
• Some plasmids may carry genes for antibiotic resistance, which enhances a bacterium's chances of surviving in the presence of antibiotics.

Significance of Plasmids

• Plasmids serve as a reservoir of genetic diversity within bacterial populations.
• They can be passed between bacterial cells through processes like conjugation, allowing for the rapid spread of beneficial traits, such as antibiotic resistance.
• Plasmids contribute to the adaptability and evolution of bacterial species.

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Organisation of DNA - Prokaryotes

Biology

Summary

In prokaryotic organisms like bacteria, DNA lacks a membrane-bound nucleus and is freely found in the cytoplasm. The bacterial genome consists of a single circular chromosome containing essential genes. Additionally, bacteria possess plasmids, extra circles of DNA, which may carry advantageous genes like antibiotic resistance. Plasmids enhance a bacterium's adaptability and play a crucial role in its survival and evolution.