Q.69 Match List I with List II
| LIST I | LIST II |
|---|---|
| A. Maple Syrup Urine Disease B. Phenylketonuria C. Leucine D. Valine |
I. Phenylalanine hydroxylase II. Essential amino acid III. Branched chain α-keto acid dehydrogenase complex IV. Ketogenic amino acid |
Choose the correct answer from the options given below:
- A-III, B-IV, C-II, D-I
- A-I, B-III, C-II, D-IV
- A-III, B-I, C-IV, D-II
- A-II, B-I, C-IV, D-III
Correct Answer: A-III, B-I, C-IV, D-II
Maple Syrup Urine Disease links to the branched chain α-keto acid dehydrogenase complex deficiency, Phenylketonuria to phenylalanine hydroxylase, leucine qualifies as ketogenic, and valine as essential.
Option Analysis
A. Maple Syrup Urine Disease – III. Branched chain α-keto acid dehydrogenase complex
True. MSUD results from deficiency in this multi-enzyme complex metabolizing leucine, isoleucine, and valine branched-chain amino acids, causing toxic ketoacid accumulation.
B. Phenylketonuria – I. Phenylalanine hydroxylase
True. PKU stems from PAH enzyme defect, blocking phenylalanine conversion to tyrosine and leading to hyperphenylalaninemia and neurological damage if untreated.
C. Leucine – IV. Ketogenic amino acid
True. Leucine catabolism yields acetyl-CoA and acetoacetate, pure ketogenic precursors for ketone body synthesis during fasting.
D. Valine – II. Essential amino acid
True. Valine, a branched-chain amino acid, cannot be synthesized by humans and must be obtained through diet.
Incorrect Options Explained
-
A-III, B-IV, C-II, D-I: Wrong—B (PKU) mismatches ketogenic amino acid; D (valine) mismatches phenylalanine hydroxylase.
-
A-I, B-III, C-II, D-IV: Wrong—A (MSUD) mismatches PAH; B mismatches dehydrogenase; D mismatches ketogenic.
-
A-II, B-I, C-IV, D-III: Wrong—A mismatches essential amino acid; D mismatches dehydrogenase.
Introduction to Amino Acid Disorders Matching
Maple syrup urine disease phenylketonuria leucine valine matching questions test inborn errors of metabolism and amino acid classification, core for GATE Life Sciences preparation. This breakdown matches diseases to enzymes and amino acids to properties precisely.
Maple Syrup Urine Disease Enzyme Defect
MSUD arises from branched chain α-keto acid dehydrogenase complex failure, accumulating leucine/valine/isoleucine ketoacids with characteristic sweet urine odor. Newborn screening detects elevated branched-chain amino acids.
Phenylketonuria and Phenylalanine Hydroxylase
PAH deficiency prevents phenylalanine hydroxylation to tyrosine, causing mental retardation unless diet-restricted. Guthrie bacterial inhibition assay historically screened newborns.
Leucine as Ketogenic Amino Acid
Purely ketogenic, leucine degrades via isovaleryl-CoA to acetyl-CoA/acetoacetate, fueling ketogenesis without glucogenic input—vital in starvation states.
Valine: Essential Branched-Chain Amino Acid
Non-synthesizable by humans, valine joins leucine/isoleucine in muscle protein synthesis and energy production, requiring dietary protein sources.
Match List I List II Correct? Reason A-III MSUD Dehydrogenase complex Yes Branched-chain defect B-I PKU PAH enzyme Yes Phenylalanine block C-IV Leucine Ketogenic Yes Acetyl-CoA pathway D-II Valine Essential AA Yes Dietary requirement -
