IB Biology HL B1.2.8 Secondary Protein Structure Question Bank

Practise IB Biology HL B1.2.8 by interpreting alpha helices and beta sheets and explaining the backbone hydrogen bonds that stabilise them.

Exam points

Identify alpha helices and beta sheets, then explain backbone hydrogen bonds stabilising secondary structure.
Distinguish secondary-structure hydrogen bonds from tertiary ionic, disulfide and hydrophobic interactions.

[Maximum number: 2]

Titin is the longest protein in the human body, consisting of a single strand of over 34000 amino acids.

Figure for Question B1.2.8 (HL)—Secondary structure question 1 — IB Biology HL

Describe the secondary structures represented by the arrows in the diagram.

a. beta/ $\beta$ -pleated sheets;

b. (structure held in place by) hydrogen bonds between N-H and C=O on different amino acids

OR

hydrogen bonds between sections of polypeptide running parallel or antiparallel

OR

sections of polypeptide form a pleat (when they run in opposite directions) because of the tetrahedral bond angles;

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B1.2.8 (HL)—Secondary structure question 1