Bacterial DNA is referred to as naked because it is not associated with :
- A.any scaffold
- B.proteins
- C.ribozymes
- D.plasmid
Correct answer
Explanation
The correct answer is B, proteins. In bacteria the DNA is not wrapped around histone proteins as it is in the chromosomes of eukaryotes, so it is called naked DNA.
In eukaryotic cells such as ours, DNA is wound around histone proteins to form nucleosomes, which pack into chromatin and chromosomes inside a nucleus bounded by a membrane. Bacteria are prokaryotes: they have no nuclear membrane, and their single, usually circular, DNA molecule lies in a region of the cytoplasm called the nucleoid, without histones. Many bacteria also carry small extra rings of DNA called plasmids, which often hold genes for antibiotic resistance and are used as vectors in genetic engineering.
A is wrong because the term naked refers to the absence of histone proteins, not of a scaffold. C is wrong because ribozymes are RNA molecules that act as enzymes and have nothing to do with how DNA is packed. D is wrong because plasmids are separate DNA rings found in many bacteria; their presence or absence does not make the main DNA naked.
Exam tip: eukaryotic DNA plus histones makes chromatin; prokaryotic DNA lies naked in the nucleoid.
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