NTR University Biochemistry Paper-I - Important Questions (Exam Tomorrow)

Strategy: Focus on high-mark chapters first. Carbohydrate (16 marks) + Vitamins (15 marks) + Lipids (15 marks) = 46 marks alone! Master these three first.

🔴 PRIORITY 1 - Carbohydrate Chemistry & Metabolism (16 Marks)

Long Essays (10 marks each - expect 1-2 questions)

1. Glycolysis (EMP pathway) - Write all steps with enzymes, energy yield (net 2 ATP), regulation (phosphofructokinase-1), substrate-level phosphorylation
2. TCA Cycle (Krebs Cycle) - All 8 steps, enzymes, products (3 NADH, 1 FADH2, 1 GTP per turn), regulation points, total ATP from 1 glucose
3. Glycogen metabolism - Glycogenesis vs glycogenolysis, enzymes (glycogen synthase, phosphorylase), hormonal regulation (insulin vs glucagon)

Short Essays (5 marks each)

1. HMP shunt (Pentose phosphate pathway) - Significance: NADPH production, ribose-5-phosphate; G6PD deficiency and hemolytic anemia
2. Gluconeogenesis - Substrates, key enzymes, Cori cycle, regulation
3. Glucose transporters (GLUTs) - GLUT1-4, locations, significance
4. Glycemic Index and diabetes-related carbohydrate metabolism
5. Fructose and Galactose metabolism - Enzyme deficiencies (galactosemia, essential fructosuria)
6. Pasteur effect - Relationship between aerobic/anaerobic metabolism
7. Lactate metabolism and Cori cycle

🔴 PRIORITY 2 - Vitamins (15 Marks)

Long Essays (10 marks)

1. Fat-soluble vitamins overview - Vitamins A, D, E, K: sources, active forms, functions, deficiency diseases, toxicity
2. Vitamin B complex (Water-soluble) - Especially B1 (thiamine/beriberi), B2 (riboflavin), B3 (niacin/pellagra), B6 (pyridoxine), B12 (cobalamin/pernicious anemia), Folic acid (megaloblastic anemia)
3. Vitamin D metabolism - 7-dehydrocholesterol → cholecalciferol → 25-OH-D3 → 1,25-(OH)2-D3 (calcitriol); regulation; rickets/osteomalacia

Short Essays (5 marks)

1. Vitamin C (Ascorbic acid) - Scurvy, collagen synthesis, antioxidant role
2. Vitamin K - Coagulation factors (II, VII, IX, X), warfarin mechanism
3. Coenzyme roles of B vitamins - NAD+/NADP+ (B3), FAD/FMN (B2), CoA (B5/pantothenic acid), TPP (B1)
4. Vitamin A - Rhodopsin/vision cycle, night blindness, retinoic acid in gene expression
5. Biotin - Carboxylation reactions, avidin antagonism
6. Folic acid vs Vitamin B12 - Megaloblastic anemia, methylfolate trap, neural tube defects

🔴 PRIORITY 3 - Lipid Chemistry & Metabolism (15 Marks)

Long Essays (10 marks)

1. Beta-oxidation of fatty acids - Activation, steps in mitochondria, energy yield from palmitic acid (129 ATP), odd-chain fatty acids
2. Cholesterol metabolism - Synthesis (HMG-CoA reductase pathway), regulation, bile acid formation, steroid hormones; statins mechanism
3. Lipoproteins - Structure, classification (chylomicrons, VLDL, IDL, LDL, HDL), functions, apoprotein roles, lipoprotein lipase

Short Essays (5 marks)

1. Fatty acid synthesis (De novo) - Acetyl-CoA carboxylase, fatty acid synthase, NADPH requirement, even-numbered fatty acids produced
2. Ketone bodies - Formation (ketogenesis), utilization, ketoacidosis - diabetes connection
3. Essential fatty acids - Linoleic acid, linolenic acid, arachidonic acid, prostaglandin synthesis
4. Phospholipids - Structure, types (lecithin, cephalin), sphingomyelin, role in membranes, surfactant
5. Reverse cholesterol transport - HDL function, LCAT enzyme
6. Obesity and lipid metabolism - Adipose tissue triglyceride metabolism, hormone-sensitive lipase

🟡 PRIORITY 4 - Heme Metabolism (10 Marks)

Long Essay (10 marks) - Very commonly asked!

1. Bilirubin metabolism - Hemoglobin breakdown → heme → biliverdin → unconjugated bilirubin → liver conjugation → conjugated bilirubin → urobilinogen/stercobilinogen; jaundice types (pre-hepatic, hepatic, post-hepatic)

Short Essays

1. Heme synthesis - Succinyl-CoA + glycine → ALA → porphobilinogen → heme; ALA synthase regulation; porphyrias
2. Types of jaundice - Hemolytic vs obstructive vs hepatocellular; lab differentiation
3. Porphyrias - Acute intermittent porphyria, erythropoietic porphyria

🟡 PRIORITY 5 - Enzymes (8 Marks)

Long Essay

1. Enzyme kinetics - Michaelis-Menten equation, Km and Vmax, Lineweaver-Burk plot, significance of Km

Short Essays

1. Enzyme inhibition - Competitive vs non-competitive vs uncompetitive inhibition with examples
2. Isoenzymes - LDH isoenzymes (LDH1 in heart, LDH5 in liver), CK isoenzymes (CK-MB in MI)
3. Regulation of enzymes - Allosteric regulation, covalent modification (phosphorylation/dephosphorylation), zymogen activation
4. Coenzymes and cofactors - Examples and their vitamin precursors
5. Clinical significance of serum enzymes - AST, ALT, ALP, GGT, amylase, lipase in disease diagnosis

🟡 PRIORITY 6 - Biological Oxidation (8 Marks)

Long Essay

1. Electron Transport Chain (ETC) - Complexes I-IV, electron carriers (NADH, FADH2, CoQ, cytochrome c), proton gradient, ATP synthase (Complex V); P:O ratio

Short Essays

1. Oxidative phosphorylation - Chemiosmotic hypothesis (Mitchell), inhibitors (rotenone, antimycin A, cyanide, oligomycin)
2. Free energy and redox potential - Standard reduction potential, relationship to ΔG
3. Uncouplers - 2,4-DNP, thermogenin (brown adipose tissue), mechanism

🟡 PRIORITY 7 - Nutrition (8 Marks)

Short Essays

1. Protein-energy malnutrition - Kwashiorkor vs Marasmus (differences in detail - very commonly asked!)
2. Balanced diet - Recommended dietary allowances, caloric value of nutrients (carb=4, protein=4, fat=9 kcal/g)
3. Dietary fiber - Types, health benefits
4. BMI and nutritional assessment
5. Essential amino acids - List all 10, limiting amino acids in foods

🟠 PRIORITY 8 - Organ Function Tests (8 Marks)

Short Essays

1. Liver function tests - Bilirubin, transaminases (AST/ALT), ALP, GGT, albumin, prothrombin time, their significance
2. Kidney function tests - Serum creatinine, BUN, creatinine clearance, GFR, urine analysis
3. Thyroid function tests - T3, T4, TSH, clinical interpretation
4. Cardiac biomarkers - Troponin I & T, CK-MB, myoglobin in MI

🟢 PRIORITY 9 - Digestion & Absorption (3 Marks)

Short Notes

1. Digestion of carbohydrates - Salivary amylase → pancreatic amylase → brush border enzymes → monosaccharide absorption
2. Fat digestion and absorption - Bile salts, micelle formation, chylomicron formation, long vs short chain fatty acid absorption
3. Protein digestion - Pepsin, trypsin, chymotrypsin, peptidases

🟢 PRIORITY 10 - Detoxification (3 Marks)

Short Notes

1. Biotransformation - Phase I (oxidation/reduction/hydrolysis via CYP450) and Phase II reactions (conjugation - glucuronidation, sulfation, acetylation)
2. Microsomal enzyme induction - Examples: phenobarbitone, rifampicin
3. Glutathione - Role in detoxification, GSH in paracetamol toxicity

🟢 PRIORITY 11 - Free Radicals & Antioxidants (3 Marks)

Short Notes

1. Free radicals - ROS: O2•-, H2O2, •OH; sources, damage to DNA/lipids/proteins
2. Antioxidant defense - Enzymatic (SOD, catalase, GSH peroxidase) and non-enzymatic (Vitamins C, E, beta-carotene, selenium)
3. Lipid peroxidation - Mechanism, malondialdehyde (MDA) as marker

🟢 PRIORITY 12 - Integration of Metabolism & Homeostasis (3 Marks)

Short Notes

1. Metabolic interrelationships - Fed state vs fasting state vs starvation (fuel use in different organs)
2. Insulin vs glucagon - Anabolic vs catabolic actions on carbohydrate/lipid/protein metabolism
3. Glucose homeostasis - Role of liver, muscle, brain in maintaining blood glucose

⚡ QUICK REVISION - Most Likely Short Note Topics (2-3 marks)

• Km and Vmax
• Lineweaver-Burk plot
• LDH isoenzymes
• Chemiosmotic hypothesis
• Cori cycle
• HMP shunt significance
• Ketone bodies
• Night blindness and Vitamin A
• Scurvy
• Pellagra
• Beriberi
• Rickets
• Pernicious anemia
• Jaundice (types)
• ALA synthase
• Kwashiorkor vs Marasmus
• SOD and catalase
• Phase I and Phase II reactions
• GLUT transporters

Exam Day Tips

• Long essays: Write in steps/numbered points with enzyme names highlighted
• Draw diagrams: TCA cycle, ETC, bilirubin metabolism, cholesterol synthesis - diagrams fetch extra marks
• For each vitamin: Always write Sources → Active form → Coenzyme role → Deficiency → Excess/toxicity
• Energy calculations: Practice the ATP yield calculations for glycolysis, TCA, and beta-oxidation
• Normal values: Memorize serum bilirubin (<1 mg/dL), AST (<40 U/L), ALT (<45 U/L), serum cholesterol (<200 mg/dL)