Chemistry Test - 12

α- Keratin which are associated the most with structural proteins. α- Keratin contains a lot of cysteine amino acids (C). These Cysteine amino acids forms disulphide bonds or bridges. These disulphide bridges are very strong covalent bonds and are not easily broken by any means. That's why disulphide bridges are so crucial to structural proteins. Also these fibrous proteins have intra-chain H-bonding. Thus, the disulphide bridges (Covalent bonds) and H - bonding cause insolubility.

Thymine and cytosine are the pyrimidine bases of DNA.

(II) and (III) are mirror images of each other that are non-superposable (not identical).

Hence, these are enantiomers.

Insulin is a hormone produced by the pancreas which is central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle.

Proteins are essential nutrients for the human body.[1] They are one of the building blocks of body tissue, and can also serve as a fuel source. Although your body can manufacture many of the 20 amino acids necessary to make proteins, it can't make them all. Those your body can't produce, called the essential amino acids, must come from the foods you eat.

The statement (D) is incorrect. Fructose is a ketohexoses and is not oxidised by mild oxidising agents, like chlorine or bromine water.

All the other statements are correct.

(A) Sucrose has an anomeric carbon which is not free. The carbon that links glucose and fructose and fructose does not have free OH group to undergo reducing reaction and to open the ring, sucrose is non-reducing.

(B) With bromine water, glucose is oxidised to gluconic acid.

(C) Glucose is dextrorotatory and rotates the plane polarised light in the clockwise direction.