Nucleoid Structure & DNA Organization — NEET Biology
✅ Asked in NEET 2023Given below are two statements: (NEET 2023) Statement I: In prokaryotes, the positively charged DNA is held with some negatively charged proteins in a region called nucleoid. Statement II: In eukaryotes, the negatively charged DNA is wrapped around the positively charged histone octamer to form nucleosome.
Given below are two statements: (NEET 2023) Statement I: In prokaryotes, the positively charged DNA is held with some negatively charged proteins in a region called nucleoid. Statement II: In eukaryotes, the negatively charged DNA is wrapped around the positively charged histone octamer to form nucleosome.
Answer & NCERT explanation
Correct answer: D — Statement I is incorrect but Statement II is true.
Statement I is incorrect: DNA is negatively charged (not positive) due to phosphate groups, and prokaryotic proteins in nucleoid are positively charged. Statement II is correct: In eukaryotes, negatively charged DNA wraps around positively charged histone octamer forming nucleosome. This charge interaction is crucial for DNA packaging as per NCERT.
Read more NCERT concept on the PYQ
In prokaryotes, such as, E. coli, though they do not have a defined nucleus, the DNA is not scattered throughout the cell. DNA (being negatively charged) is held with some proteins (that have positive charges) in a region termed as 'nucleoid'. The DNA in nucleoid is organised in large loops held by proteins.
In prokaryotes like E. coli, DNA is organized in the nucleoid region through electrostatic interactions: negatively charged DNA binds to positively charged proteins, forming large supercoiled loops. NTA tests this because students often confuse nucleoid with nucleus or assume prokaryotic DNA is randomly scattered. The common mistake is forgetting that proteins actively organize prokaryotic DNA despite the absence of a membrane-bound nucleus. To score correctly, remember: nucleoid = protein-organized DNA loops held by ionic charges, NOT a nucleus, and this organization is essential for gene regulation and DNA replication in prokaryotes.
What does NCERT say about prokaryotes such as E?
Has this concept appeared in NEET?
Which chapter is this from?
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