Which of the following contains a Glycosamine unit?

All of these

The correct answer is option 4. All of these.

Let us break down the role of glycosamines in the contexts of Heparin, Nucleic Acids, and Chitin:

1. Heparin

Heparin is a type of glycosaminoglycan, which is a class of polysaccharides. Glycosaminoglycans are composed of repeating disaccharide units, where one of the sugars in the disaccharide is a glycosamine. In heparin, the glycosamine unit is primarily N-sulfated glucosamine. This unit contributes to heparin's function as an anticoagulant by interacting with various proteins involved in blood clotting.

2. Nucleic Acids

Nucleic acids (DNA and RNA) are composed of nucleotides, which consist of a phosphate group, a sugar (ribose in RNA and deoxyribose in DNA), and a nitrogenous base. The building blocks of DNA and RNA, nucleotides, contain a sugar molecule, which can be either ribose or deoxyribose. These sugars are linked to a phosphate group and a nitrogenous base. Deoxyribose is a type of glycosamine.

3. Chitin

Chitin is a structural polysaccharide found in the exoskeletons of arthropods and the cell walls of fungi. It is composed of repeating units of N-acetylglucosamine, a type of glycosamine. The N-acetylglucosamine unit in chitin provides structural support and rigidity.

Summary

Heparin and Chitin contain glycosamine units, specifically N-sulfated glucosamine in heparin and N-acetylglucosamine in chitin. In nucleic acids, deoxyribose is a type of glycosamine.

Thus, the correct answer is option 4. All of these.