alleryStart learning →What sits at the two ends of a polypeptide chain?
AA free amino group at one end, a free carboxyl at the other
BA free amino group at one end, a free R group at the other
CA free carboxyl group at both ends of the finished chain
DA free phosphate at one end, a free carboxyl at the other
Answer & Solution
Correct answer: A. A free amino group at one end, a free carboxyl at the other
1. Inside the chain every amino group and carboxyl group is used up in a peptide bond.
2. Only the two ends escape that, so each polypeptide has one free amino group and one free carboxyl group.
3. The end with the free amino group is the N terminal, or amino terminal.
4. The end with the free carboxyl group is the C terminal, or carboxyl terminal.
5. Two free carboxyl groups would leave no amino end for the chain to have been extended from.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 3 "Biological Macromolecules", section 3.4 Proteins_
Keep practising Biological Macromolecules
Browse all Biological Macromolecules questions for CSIR NET, or explore more Biology topics.
Related questions
Even though RNA is single stranded, what shape does most RNA still take?Which RNA is the smallest, and what does it do?What is the role of transfer RNA in protein synthesis?If a DNA strand reads AATTGCGC, what is the sequence of the complementary RNA?Which are the four major types of RNA?How is RNA built compared with DNA?If one DNA strand reads AATTGGCC, what does its complementary strand read?What distance separates one base pair from the next in the DNA double helix?