Protein Structure and Function MCQs

Ans. A: 1.1 Each 100 grams of breast milk yields approximately: 65 Kilocalories 88 g water 7.4 g carbohydrates (primarily lactose) 3.4 g fat 1.1 g protein 871. It waste contain toxic substances, organic load is measured by ? a) Biological oxygen demand b) Chemical oxygen demand c) Suspended solid d) None Correct Answer - B Ans. is 'b' i.e., Chemical oxygen demand [Ref Park 22"d/e p. 708] " The strength of sewage is expressed in terms of :

Phase II detoxification involves mainly conjugation reactions. Some alcohols, arylamines, and phenols are sulfated and detoxified in body. Option A: SAM is a donor of methyl group during conjugation as well as other methylation reaction in body. Option B: SAH is not involve as donor of sulfate group during conjugation reactions. Option C: The sulfate donor in conjugation reaction of phase II detoxification is active sulfate adenosine 3'-phosphate-5'-phosphosulfate (PAPS). PAPS is also a sulfate donor in other biologic and sulfation reactions eg, sulfation of steroids, glycosaminoglycans, glycolipids, and glycoproteins. Option D: GSH (Glutathione) act as conjugating agent during phase II detoxification reaction, but not as sulfate donor. Reference: Harper's illustrated biochemistry 32nd edition CH 47 PN 558

Explanatio: Glucagon is a catabolic hormone secreted in the fasting state to increase blood glucose levels. Its actions are antagonistic to insulin. Glucagon inhibits glycolysis in the liver to prevent the use of glucose for energy production, thereby conserving it for release into the bloodstream. Instead, it promotes processes that generate glucose: Gluconeogenesis (Option B ruled out): Stimulates glucose production from non-carbohydrate precursors. Glycogenolysis (Option C ruled out): Stimulates the breakdown of glycogen to glucose. Ketogenesis (Option D ruled out): In prolonged fasting, stimulates ketone body production from fatty acids. Key Takeaways: Glucagon's primary role is to raise blood glucose by stimulating gluconeogenesis and glycogenolysis while inhibiting glycolysis.

Option A: In type I DM, the lack of insulin to antagonize the actions of glucagon results in increased lipolysis in adipose tissue and the resultant nonesterified fatty acids are substrates for ketogenesis in the liver. Option C: In poorly controlled type 1 diabetes mellitus, patients may become hyperglycemic, both as a result of lack of insulin to stimulate uptake and utilization of glucose and because in the absence of insulin to antagonize the actions of glucagon, there is increased gluconeogenesis from amino acids in the liver (increased hepatic glucose output). Option B: Increased protein catabolism to produce glucose by gluconeogenesis. Option D: Insulin insufficiency also reduced glucose uptake.

Explanation: Normal Calcium Levels in Blood Total Calcium: Includes both ionized (free) calcium and calcium bound to proteins like albumin. The normal range for total calcium is: 8.5-10.5 mg/dL (or 2.1-2.6 mmol/L). Ionised Calcium: The physiologically active form that is not bound to proteins. This is crucial for biological functions and is often measured in specific cases. The normal range for ionised calcium is: 4.5-5.5 mg/dL (or 1.1-1.3 mmol/L).

Ans. is 'c' i.e., SDS-PAGE [Ref Vasudevan 6"die p. 600]

There is only a limited capacity to metabolize vitamin A, and excessive intakes lead to accumulation beyond the capacity of intracellular binding proteins. Unbound vitamin A causes membrane lysis and tissue damage. Symptoms of toxicity affect: central nervous system (headache, nausea, ataxia, and anorexia, all associated with increased cerebrospinal fluid pressure; aka Pseudotumour cerebri) the liver (hepatomegaly with histological changes and hyperlipidemia) calcium homeostasis (thickening of the long bones, hypercalcemia, and calcification of soft tissues) skin (excessive dryness, desquamation, and alopecia). Reference: Harper's illustrated biochemistry 32nd edition, page 1297

Iron-sulfur proteins (nonheme iron proteins, Fe-S) are found in Complexes I, II, and III (Option A, Option B, Option C), but not found in Complex IV (Option D). So option D is correct option. Reference: Harper's illustrated biochemistry 32nd edition CH 13 PN 118