A-LevelBiologyBiological moleculesFeb/Mar 2025Paper 1 Q101 Mark
Hydroxyproline is synthesised by addition of an –OH group to the R-group of the amino acid proline. Hydroxyproline is a major component of collagen and has an important role in increasing the stability of its structure. Which statement explains why the addition of an –OH group to proline could increase the stability of collagen?
AIt strengthens hydrogen bonding between the R-groups of adjacent polypeptide chains, resulting in a tertiary structure that is more resistant to heat denaturation.
BIt increases the number of sites available for the formation of hydrogen bonds within the secondary structure of collagen, resulting in more stable alpha helices.
CIt increases the formation of hydrogen bonds between R-groups and water molecules, which help to hold the chains of the collagen triple helix together by strengthening hydrophilic interactions.
DIt strengthens the quaternary structure of collagen by providing more sites for hydrogen bonding between the R-groups of distantly separated amino acids within the same polypeptide chain.
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The correct answer is C. This question tests the candidate's understanding of biological molecules within the Biologysyllabus. The examiner's mark scheme requires...
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