Answer: [A]=[T] and [G]=[C].
- A [A]=[T] and [G]=[C]
- B [A]=[G] and [T]=[C]
- C [A]+[T]=[G]+[C]
- D All bases are equal
Correct answer: A. [A]=[T] and [G]=[C]
Explanation: Chargaff's rule: adenine pairs with thymine and guanine pairs with cytosine; so [A]=[T] and [G]=[C].
Two amino acids join via a condensation reaction: the carboxyl -OH of one and an amine -H of the other are eliminated as water, leaving a peptide bond (-CO-NH-) linking them into a dipeptide; repeating this builds a full protein chain.
Concept context
The chemistry of life: carbohydrates, proteins, lipids, nucleic acids, enzymes, and vitamins. Understand their structures, classification, and biological functions. Highly relevant for NEET and Class 12 board exams.