Question

Histone proteins are positively charged because they are rich in basic amino acid residues

• A. Arginine and Proline
• B. Arginine and Alanine
• C. Arginine and Lysine
• D. Arginine and Phenylalanine

Answer 1

The Correct Option is C

Histone proteins are a class of proteins that play a crucial role in DNA packaging in eukaryotic cells. They are positively charged due to the presence of basic amino acids in their structure.

The basic amino acids that contribute to the positive charge of histones are arginine and lysine.

• Arginine contains a positively charged guanidino group in its side chain, which is important for interactions with the negatively charged phosphate backbone of DNA.
• Lysine has an amino group (-NH₂) that is positively charged under physiological conditions and helps in binding to the DNA.

These positive charges help histones interact with the negatively charged DNA, aiding in the formation of nucleosomes, which are the building blocks of chromatin.

Thus, histone proteins are rich in arginine and lysine residues, which makes them positively charged.

The correct answer is (C) : Arginine and Lysine

Answer 2

Histone proteins are positively charged because they are rich in basic amino acid residues.

The correct answer is: (C) Arginine and Lysine.

Histone proteins are positively charged due to the high presence of basic amino acids, which contain amino groups that attract negatively charged molecules such as DNA. The amino acids Arginine and Lysine are particularly abundant in histone proteins and contribute to their positive charge.

These amino acids contain amino groups (-NH₂) in their side chains, which can form ionic bonds with the negatively charged phosphate groups of DNA. This interaction helps histones bind tightly to DNA, allowing them to package and organize the DNA into nucleosomes, which is crucial for the structure and function of chromosomes.

Thus, the positive charge of histone proteins is primarily due to the presence of Arginine and Lysine residues.