DP Chemistry (last assessment 2024)

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Question 17N.3.sl.TZ0.21

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Date November 2017 Marks available [Maximum mark: 3] Reference code 17N.3.sl.TZ0.21
Level sl Paper 3 Time zone TZ0
Command term Explain Question number 21 Adapted from N/A
21.
[Maximum mark: 3]
17N.3.sl.TZ0.21

Molecules of antibiotics often contain a beta-lactam ring. Explain the importance of the betalactam ring in the action of penicillin, using section 37 of the data booklet.

[3]

Markscheme

ring is «sterically» strained

OR

angles of 90° instead of 109.5/109/120° angles

OR

angles smaller than 109.5/109/120°/tetrahedral/trigonal planar/triangular planar angle

ring breaks up/opens/reacts «easily»

OR

amido/amine group «in ring» is «highly» reactive

binds to/reacts with/interferes with/inactivates transpeptidase

OR

binds to/reacts with/interferes with/inactivates enzyme responsible for bacterial cell wall formation/cross-linking

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