a. The diagram below shows the structures of three amino acids.

i. Draw a diagram to show the structure of the tripeptide with the following sequence: 

alanine–glycine–serine.

ii. What is the name given to the sequence of amino acids in a protein?

iii. What substance, apart from the tripeptide, would be formed when the three amino acids combine?

iv Draw a ring around an atom or group of atoms making up an R group that could hydrogen bond with a neighbouring R group.

v. Draw a ring around and label the peptide bond(s) you have drawn in the diagram.

vi. Draw a ring around a group of atoms which could hydrogen bond with a –CO – group in an alpha helix (α-helix). Label this group A.

b. State three features that α-helices and beta sheets (β-sheets) have in common.

c. A protein can be described as a polymer. State the meaning of the term polymer.

d. X and Y represent two different amino acids.

i. Write down the sequences of all the possible tripeptides that could be made with just these two amino acids.

ii. From your answer to d i, what is the formula for calculating the number of different tripeptides that can be formed from two different amino acids?

Transcribed Image Text:

OH CH, H CH, H H. N - N - H он H он он H alanine glycine serine