Question

1. the image to the right represents a growing polypeptide chain. what does directionality refer to in terms of polypeptides? label the image to the right accordingly.

Explanation:

In polypeptides, directionality refers to the orientation of the chain based on the amino - and carboxyl - termini. The end with a free amino group ($NH_2$) is called the N - terminus (amino - terminus) and the end with a free carboxyl group ($COOH$) is called the C - terminus (carboxyl - terminus). For the given polypeptide chain, the left - hand side with $NH_2$ is the N - terminus and the right - hand side with $COOH$ is the C - terminus.

Answer:

Label the left - most $NH_2$ group as N - terminus and the right - most $COOH$ group as C - terminus.