The following statements are made regarding the nature of the chromosomes in bacteria.

A. Most bacterial chromosomes are circular. However, in few bacteria, linear chromosomes exist.
B. All the bacterial systems are known to have a single chromosome.
C. Some bacterial chromosomes contain enhancer-like elements.
D. Chromosomes in bacteria are stabilized by histone-like proteins.

Which one of the following options represents the combination of all correct statements?

Correct option is D

Explanation

• A (Most bacterial chromosomes are circular, but some are linear) – Correct

  • The majority of bacterial species have circular chromosomes (e.g., E. coli).
  • However, some bacteria such as Borrelia burgdorferi (causative agent of Lyme disease) and Streptomyces species have linear chromosomes.

• B (All bacteria have a single chromosome) – Incorrect

  • Many bacteria contain a single chromosome, but some species have multiple chromosomes.
  • Example: Vibrio cholerae has two circular chromosomes instead of one.

• C (Some bacterial chromosomes contain enhancer-like elements) – Correct

  • Although bacteria do not have traditional enhancers like eukaryotes, studies suggest that bacterial DNA contains enhancer-like sequences that regulate gene expression.
  • Some bacteria use upstream activator sequences that function similarly to eukaryotic enhancers.

• D (Chromosomes in bacteria are stabilized by histone-like proteins) – Correct

  • Unlike eukaryotes, bacteria do not have true histones, but they do contain histone-like proteins such as HU, H-NS, and Fis, which help in DNA packaging and stability.

Thus, the correct choice is A, C, and D (Option 4).

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