Question

One of the peptides that can be recovered after gluten digestion is 33 residues long; 13 of the 33 residues are proline. How many times would you expect proline to appear in this peptide if it were made up of a completely random assortment of the 20 most common amino acids?

Answer 1

It's expected that proline would appear between once or twice.

Explanation:

If it were made up of a random assortment of amino acids, each amino acid can have:

`(1)/(20)` chance of being in any particular place in the sequence.

Therefore, Proline has a
`(1)/(20)` chance of being in each place.

We've got 33 places,

So if we can multiply the places we've got times the chances and we get:

`33*(1)/(20) = (33)/(20)` or 1.65

Therefore it's expected that proline would appear between once or twice.