The following statements (I - V) are either true or false characteristics and fu
ID: 142900 • Letter: T
Question
The following statements (I - V) are either true or false characteristics and functions of the important protein lactate dehydrogenase (LDH) I. II. The two subunits LDH-H and LDH-M are encoded by the LDHA and LDHB genes III. High levels of LDH in cerebrospinal fluid are often associated with bacterial IV. Mutations in the LDHA gene and resulting deficiencies in LDH-H activity can result V. LDH enzymes are most commonly specific for L-lactate and these L-LDH enzymes Plasma total LDH level is elevated in hemolysis respectively meningitis in Glycogen Storage Disease XI. have the EC number 1.1.1.27; D-LDH enzymes have the EC number 11.1.28 Which of the following options (A E) is/are CORRECT? (a) (b) (c) (d) (e) Statements I, III and V are true. Statements II, IV and V are false. Statements II and IV are false. All statements are false All statements are true. Arsenate is a toxic ion that can interfere with both glycolysis and oxidative phosphorylation. Arsenate resembles inorganic phosphate (P) and can replace it in many enzymatic reactions. One such reaction is catalysed by glyceraldehyde 3-phosphate dehydrogenase in glycolysis. Arsenate competes with phosphate for entry into the active site of glyceraldehyde 3-phosphate dehydrogenase and upon completion of the reaction instead of the normal product, 1,3-bisphosphoglycerate, the mixed anhydride 1-arsenato- 3-phosphoglycerate is formed: this undergoes rapid spontaneous hydrolysis into arsenate plus 3-phosphoglycerate, the latter being a normal intermediate in glycolysis, so glycolysis is able to proceed from the step at 3-phosphoglycerate. What would be the effect of arsenate in glycolysis? (a) Arsenate activates glycolysis so that more ATP and NADH is generated for every glucose molecule. In the presence of arsenate there is no net formation of ATP from glycolysis, but NADH generation is not directly affected Arsenate brings glycolysis to an abrupt stop with immediate lethal consequences In the presence of arsenate glycolysis produces fewer ATP and NADH molecules per glucose molecule Arsenate does not affect the number of ATP or NADH molecules generated per qlucose molecule, (b) (c) (d) (e)Explanation / Answer
LDH:
"I" is correct as plasma total LDH level is elevated in hemolysis. Damaged tissues release more LDH in blood.
"II" is incorrect because LDH-H and LDH-M are encoded by LDHB and LDHA genes respectively.
"III" is true.
"IV" is incorrect because Glycogen storage disease XI is caused due to homozygous mutation in LDHA gene. But LDHA gene encodes LDH-M, not LDH-H.
"V" is correct.
Thus, I, III and V are true while II and VI are false.
Correct answer will be (a) and (c).
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Arsenate:
The correct option will be (d) In the presence of arsenate glycolysis produces fewer ATP and NADH molecules per glucose molecule.