Long answer question (15marks) 1. Write a detail note on urea cycle with reaction? Mention its major metablic disorders . 2. Explain the transamination reaction ? Involved in the catabolism of amino acids. 3. What are the bile pigments. Name the diseases aassociated with their metablism. 4. What are transaminase. Write the fiagnostic importance of transaminases. 5. What are porphyrin. Explain the type and clinical importance of porphyria. Short answer question ( 5 marks) 1. Explain the transamination reaction involved in thr catabolism of amino avids. 2. Explain phenoketoneumia and alkaptoneumia 3. What is porphyria? 4. What is jaundice? Explain the different types of jaundice? 5. What is normal blood urea level? Name two condition in which blood urea level is elevated .
Quick Reference Guide
Long Answer Questions (15 Marks)
| Q | Topic | Key Points to Emphasize |
|---|---|---|
| 1 | Urea Cycle | 5 steps (CPS-I → OTC → ArgSucc Synthetase → ArgSucc Lyase → Arginase); 2N from NH₄⁺ and aspartate; 3 ATP consumed; 6 enzyme defect disorders |
| 2 | Transamination | PLP coenzyme; ping-pong mechanism; α-KG/Glutamate as universal pair; all AA except Lys/Thr; link to urea cycle via oxidative deamination |
| 3 | Bile Pigments | Heme → Biliverdin → Bilirubin (unconjugated) → Bilirubin diglucuronide → Urobilinogen → Stercobilin/Urobilin; diseases: hemolytic, hepatocellular, obstructive jaundice, Gilbert's, Crigler-Najjar, Dubin-Johnson |
| 4 | Transaminases | AST (GOT) and ALT (GPT); PLP-dependent; diagnostic: hepatitis (ALT > AST), alcoholic liver disease (AST:ALT > 2:1), MI (AST); normal values |
| 5 | Porphyrins/Porphyria | 8-step heme synthesis; hepatic vs. erythropoietic; AIP (PBG deaminase deficiency) — neurovisceral; PCT — cutaneous; treatment: hemin, glucose, givosiran |
Short Answer Questions (5 Marks)
| Q | Topic | Core Answer |
|---|---|---|
| S1 | Transamination | Same as Long Q2 but condensed |
| S2 | PKU & Alkaptonuria | PKU: PAH deficiency, mental retardation, low-Phe diet; Alkaptonuria: homogentisate oxidase deficiency, dark urine, ochronosis, arthritis |
| S3 | Porphyria | Heme enzyme defects; hepatic (neurovisceral) vs. erythropoietic (cutaneous) |
| S4 | Jaundice | Pre-hepatic/Hepatic/Post-hepatic — distinguished by urine color, stool color, urobilinogen, ALP, AST/ALT |
| S5 | Blood Urea Level | Normal: 15–40 mg/dL (BUN: 7–20 mg/dL); elevated in: AKI, CKD, high-protein diet, dehydration, GI bleed, obstruction |