Correct option is C
Explanation-
CENP-A (Centromere Protein A) is a histone H3 variant. It replaces canonical histone H3 specifically at centromeric nucleosomes. It plays a critical role in centromere identity, kinetochore assembly and chromosome segregation during mitosis and meiosis
The nucleosome core is made of H2A, H2B, H3, and H4, with H3 playing a central role in chromatin structure and epigenetic regulation. At centromeres, CENP-A replaces H3 to mark this region uniquely, without altering the nucleosome’s overall structure. CENP-A is functionally and structurally similar to histone H3, but with key modifications that allow it to direct centromere function.
Incorrect options -
Option A - . H1 - H1 is a Linker histone . H1 is not part of the nucleosome core. It stabilizes linker DNA, not replaced by CENP-A.
Option B - H2A - H2A is a Core histone . It is important in nucleosome structure, but CENP-A is not a variant of H2A.
Option D - H4 - H4 is a core histone. H4 is partner of H3 in the nucleosome, but not replaced at centromeres.
So, the correct answer is option C - H3
