This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Molecular Genetics, Subject name: Biochemistry
Proteins seen in chromosomes are called: 
Select and explain. 
A. Nucleotides, B. Histones, C. Apoproteins, D. Glycoproteins
B: Histones
Answer: B: Histones 
Explanation: Ans: b (Histones) Ref: Vasudevan, 4th ed, p. 398; 5th ed, p. 416* Histones are proteins rich in basic amino acids. DNA wraps around histone octamer to form one nucleosome.* Histones are rich in lysine and arginine.* Histone octamer contains two copies each of histones (H2A, H2B, H3 H4)* H, histone is associated with the linker DNA found between nucleosomes.* Eu chromatin - loosely packed and transcriptionaly active.* Hetero chromatin - tightly packed and inactive.Topo isomearses are enzymes that can change the amount or super coiling.