Question 1
Multiple choiceEasy1 markA student is considering possible polypeptides assembled from the 20 amino acids represented in the genetic code. Which statements describe the possible chains?
I. Two chains can contain the same amino-acid types in different orders.
II. Each chain must contain all 20 amino-acid types.
III. Chains can range in length from a few amino acids to thousands.
Show answer and explanation
Answer: C. The 20 amino-acid types are possible building blocks, but their order and the length of a polypeptide chain can vary. Thus I and III are correct; a chain need not contain every type.
A: accepts variation in order but incorrectly assumes chain length cannot vary.
B: accepts variation in length but assumes amino-acid order is fixed.
D: mistakes the 20 amino acids available for a set that every chain must contain.
Remember: a polypeptide can use a subset of the 20 amino-acid types in different orders and chain lengths.