Answer
If only 10 different amino acids were used, then the number of distinct peptides generated would reduce to $10^5$. Thus, the number of distinct peptides will decrease $32$ times.
Proteins are much longer and thus result in a huge reduction in protein diversity.
Work Step by Step
The primary structure is responsible for the formation of the 3D conformation of a protein, which determines its function. Thus, diverse protein sequence results in diverse shapes and functions.
Formula
For a peptide of length
$n$ with $k$ possible amino acids at each position, the number of possible sequences is:
Number of sequences
= $k^n$
We are given $n=5$ and $k=20$ or $k=10$.
For $k=20$ we have:
$20^5=3,200,000$ possible sequences
For $k=10$ we have:
$10^5=100,000$ possible sequences
Using only 10 amino acids reduces the possible peptide diversity by a factor of 32.
