Free Proteins and Amino Acids MCQs with Answers

• A. Arginine
• B. Tryptophan
• C. Phenylalanine
• D. Histidine

Explanation: Creatine synthesis uses arginine and glycine in the kidney or pancreas, followed by methylation using methionine-derived SAM in the liver.

• A. Cycline
• B. Calmodulin
• C. Collagen
• D. Kinesin

Explanation: Calmodulin is a small calcium-binding regulatory protein; when bound to Ca²⁺, it changes shape and activates or inhibits many target…

• A. Valine
• B. Arginine
• C. Glutamic acid
• D. Histidine

Explanation: Histidine undergoes decarboxylation to form histamine, which produces vasodilation and contributes to inflammatory responses.

• A. Decarboxylation
• B. Hydroxylation
• C. Transamination
• D. Reduction

Explanation: Histidine is converted to histamine by histidine decarboxylase, which removes its carboxyl group as CO₂.

• A. Kidney
• B. Liver
• C. Muscle
• D. Spleen

Explanation: Albumin is synthesized by hepatocytes in the liver and is the major contributor to plasma oncotic pressure.

• A. Arginine
• B. Glycine
• C. Phenylalanine
• D. Leucine

Explanation: Phenylalanine is rapidly hydroxylated to tyrosine by phenylalanine hydroxylase, requiring tetrahydrobiopterin.

• A. Hydroxyproline
• B. Proline
• C. Lysine
• D. Glycine

Explanation: Hydroxyproline is a characteristic post-translationally modified amino acid abundant in collagen and is therefore used as a biochemical…

• A. Fe+2
• B. Succinate
• C. Ascorbic acid
• D. O2

Explanation: Prolyl hydroxylase requires ferrous iron, molecular oxygen and vitamin C to hydroxylate proline residues in collagen.

• A. Used by the body
• B. Forming part of the proteins
• C. Required in the diet
• D. Absorbed in the intestines

Explanation: Nonessential amino acids are synthesized in adequate amounts by the body, so they are not normally required in the diet.

• A. Involved in melatonin in synthesis
• B. Involved in serotonin synthesis
• C. Involved in niacin synthesis
• D. Non-essential amino acid

Explanation: Tryptophan is an essential amino acid, so it must be obtained from the diet.

• A. Glycine
• B. All of the above
• C. Cysteline
• D. Valine

Explanation: Glycine, valine and cysteine can all contribute carbon skeletons to gluconeogenesis because they are glucogenic amino acids.

• A. All of the above
• B. Glutathione
• C. Purines
• D. Creatine
• E. Hemoglobin

Explanation: Glycine contributes to heme-containing hemoglobin, is a component of glutathione, and participates in the synthesis of purines and…

• A. Protamines
• B. Lactalbumin
• C. Prolamines
• D. Peptones

Explanation: Peptones are derived proteins produced by partial hydrolysis of native proteins.

• A. Acidic
• B. Basic
• C. Aromatic
• D. Branched chain

Explanation: The acidic amino acids, aspartate and glutamate, are both nonessential because the body can synthesize them.

• A. 5 gm
• B. 8 gm
• C. 10 gm
• D. 16 gm

Explanation: Typical proteins contain about 16% nitrogen by mass, based on the conventional protein factor of 6.25.

• A. Lysine
• B. Histidine
• C. Tyrosine
• D. Proline

Explanation: Proline is called an imino acid because its side chain forms a ring with the amino nitrogen, making its amino group secondary.

• A. Protein synthesis
• B. Protein degradation
• C. Protein denaturation
• D. Protein folding

Explanation: Chaperones bind newly synthesized or stressed proteins and help them reach their correct three-dimensional conformation.

• A. Hb has 2 polypeptide chains
• B. Iron is present in ferrous state
• C. Hb structurally similar to myoglobin
• D. Ferrous ions are in porphyrin rings

Explanation: Adult haemoglobin has four polypeptide chains, not two, whereas myoglobin has one chain.

• A. Sulphydryl group
• B. Carboxy terminal
• C. Amino terminal
• D. Histidine

Explanation: At physiological pH, 2,3-DPG binds in the positively charged central cavity between haemoglobin's beta chains, interacting mainly with…

• A. Leucine
• B. Valine
• C. Isoleucine
• D. Histidine

Explanation: Haem iron is coordinated to a proximal histidine residue of the globin chain, in addition to its four bonds with the porphyrin nitrogens.