PGIMER Entrance Biochemistry Syllabus

Biochemistry syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Biochemistry in PGIMER Entrance, not a summary of it.

1. 1

   Biomolecules and Enzymes

   4 topics

   • Protein structure and amino acid classification
   • Carbohydrate and lipid chemistry
   • Enzyme kinetics and inhibition
     • Michaelis-Menten and Lineweaver-Burk
     • Competitive vs non-competitive inhibition
   • Coenzymes and isoenzymes
2. 2

   Metabolism

   5 topics

   • Glycolysis, TCA cycle and oxidative phosphorylation
   • Gluconeogenesis and glycogen metabolism
   • Beta-oxidation and ketone body formation
   • Urea cycle and amino acid catabolism
   • Inborn errors of metabolism
     • Phenylketonuria and alkaptonuria
     • Glycogen and lysosomal storage disorders
3. 3

   Molecular Biology and Nutrition

   5 topics

   • DNA replication, transcription and translation
   • Gene regulation and mutations
   • PCR, blotting and recombinant DNA techniques
   • Vitamins and mineral functions and deficiencies
   • Free radicals and antioxidant defense

Biochemistry flashcards for PGIMER Entrance

19 of 59 cards from the Biochemistry deck — real questions with worked answers.

1. What are the four levels of protein structure, and which bonds stabilize each?

   Primary (peptide bonds), Secondary (hydrogen bonds — alpha-helix, beta-sheet), Tertiary (H-bonds, disulfide, ionic, hydrophobic, van der Waals), Quaternary (same non-covalent forces between subunits).

2. Classify amino acids by side-chain polarity, giving examples of each class.

   Nonpolar/hydrophobic (Gly, Ala, Val, Leu, Ile, Met, Phe, Trp, Pro); Polar uncharged (Ser, Thr, Cys, Tyr, Asn, Gln); Acidic/negatively charged (Asp, Glu); Basic/positively charged (Lys, Arg, His).

3. Which amino acids are essential (must be obtained from diet)?

   PVT TIM HaLL: Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine, Arginine (semi-essential), Leucine, Lysine.

4. What is the isoelectric point (pI) of an amino acid?

   The pH at which the amino acid carries no net charge (zwitterion), with equal positive and negative charges; calculated as the average of the two pKa values flanking the neutral species.

5. What is the Ramachandran plot used for?

   It plots the phi (φ) and psi (ψ) dihedral angles of the polypeptide backbone to show sterically allowed conformations, identifying favorable regions for alpha-helices and beta-sheets.

6. Distinguish aldoses from ketoses and give an example of each.

   Aldoses have an aldehyde group (e.g., glucose); ketoses have a ketone group (e.g., fructose).

7. What type of glycosidic bonds link glucose units in starch, glycogen, and cellulose?

   Starch: alpha-1,4 (amylose) with alpha-1,6 branches (amylopectin); Glycogen: alpha-1,4 with alpha-1,6 branches (~every 8-12 residues); Cellulose: beta-1,4 linkages.

8. Define reducing sugars and name a common non-reducing disaccharide.

   Reducing sugars have a free anomeric carbon (free aldehyde/ketone) that can reduce Cu2+ (e.g., glucose, fructose, lactose, maltose). Sucrose is non-reducing (anomeric carbons joined).

9. How are fatty acids classified as saturated vs unsaturated, and what are essential fatty acids?

   Saturated have no C=C double bonds; unsaturated have one or more. Essential fatty acids (cannot be synthesized): linoleic acid (omega-6) and alpha-linolenic acid (omega-3).

10. What distinguishes the major lipoprotein classes by density and function?

    Chylomicrons (least dense, dietary TG transport); VLDL (endogenous TG); LDL ('bad', delivers cholesterol to tissues); HDL ('good', reverse cholesterol transport, most dense).

11. Write the Michaelis-Menten equation and define its terms.

    v = (Vmax × [S]) / (Km + [S]), where v = reaction velocity, Vmax = maximum velocity, [S] = substrate concentration, Km = substrate concentration at half Vmax.

12. What does the Km value indicate about an enzyme?

    Km is the substrate concentration at half-maximal velocity; a low Km indicates high affinity for substrate, a high Km indicates low affinity.

13. What is the Lineweaver-Burk plot and its axes?

    A double-reciprocal plot of 1/v vs 1/[S]; y-intercept = 1/Vmax, x-intercept = -1/Km, slope = Km/Vmax. Used to linearize Michaelis-Menten kinetics.

14. Compare competitive, noncompetitive, and uncompetitive enzyme inhibition by their effects on Km and Vmax.

    Competitive: Km increases, Vmax unchanged. Noncompetitive: Km unchanged, Vmax decreases. Uncompetitive: both Km and Vmax decrease.

15. What is allosteric regulation of enzymes?

    Regulation in which an effector molecule binds at a site other than the active site, changing enzyme conformation and activity; gives sigmoidal kinetics (e.g., feedback inhibition).

16. Name the coenzyme derived from each vitamin: niacin, riboflavin, thiamine, pantothenic acid, and pyridoxine.

    Niacin (B3) → NAD+/NADP+; Riboflavin (B2) → FAD/FMN; Thiamine (B1) → TPP; Pantothenic acid (B5) → Coenzyme A; Pyridoxine (B6) → PLP (pyridoxal phosphate).

17. What are isoenzymes, and give a clinically important example.

    Isoenzymes are different molecular forms of an enzyme that catalyze the same reaction but differ in structure/properties. Example: LDH (5 isoforms), Creatine Kinase (CK-MM, CK-MB, CK-BB — CK-MB elevated in MI).

18. Which LDH isoenzyme predominates in cardiac muscle and is elevated after myocardial infarction?

    LDH-1 (H4); a 'flipped ratio' where LDH-1 > LDH-2 suggests myocardial infarction.

19. What is the net ATP yield and key products of glycolysis per glucose molecule?

    Net 2 ATP, 2 NADH, and 2 pyruvate per glucose (4 ATP produced minus 2 ATP consumed).

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