Digestion

• Coenzymes in Cellular Metabolism:
• NAD (Nicotinamide Adenine Dinucleotide): Pyridine nucleotide coenzyme derived from vitamin $B_3$ (niacin), functioning as an electron carrier.
• FAD (Flavin Adenine Dinucleotide): Flavin nucleotide coenzyme derived from vitamin $B_2$ (riboflavin), functioning in oxidation-reduction reactions.
• LDH (Lactate Dehydrogenase) is a full catalytic protein (enzyme).
• Proline is an imino/amino acid.
• nalysis:
• ((A) and (B) only): Correct coenzymes.

Correct option: (2) (A) and (B) only.

• Enzyme Classes in the EC Classification System:
• The International Union of Biochemistry and Molecular Biology (IUBMB) classifies all enzymes into six primary hierarchical classes (EC 1 to EC 6):

• EC 1: Oxidoreductases
• EC 2: Transferases (B)
• EC 3: Hydrolases (A)
• EC 4: Lyases
• EC 5: Isomerases (C)
  6. EC 6: Ligases (D)
  (EC 7 Translocases was added subsequently).
  • nalysis:

• All four listed groups (A, B, C, D) are official major enzyme classes. Hence, Option 3 is correct.

• Comparative Proteomics and Genome Architecture:
• Large-scale sequencing and domain architecture analyses (Pfam / SMART) across the Human Genome Project revealed:
• The human proteome is largely modular, built by shuffling ancient, highly conserved eukaryotic protein domains.
• Humans and vertebrates share virtually all of their basic protein domain repertoire with invertebrates; only a very small number ($\lt 7\%$) of protein domains are unique to vertebrates, and virtually no domain is uniquely restricted to humans alone.
• nalysis:
• (human genome contains a small number of protein domains that are unique to vertebrates): Correct.

Correct option: (2) human genome contains a small number of protein domains that are unique to vertebrates