Question 22M.1A.HL.TZ2.28
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.1A.HL.TZ2.28 |
| Level | HL | Paper | 1A | Time zone | TZ2 |
| Command term | Question number | 28 | Adapted from | N/A |
The diagram shows the structure of E. coli ribonuclease HI, a bacterial protein consisting of one polypeptide chain.
[Source: RCSB PDB. 1JL1 D10A E. coli ribonuclease HI. PDB DOI: 10.2210/pdb1JL1/pdb Mol* (Goedken, E.R., Marqusee, S. Native-state energetics of a thermostabilized variant of ribonuclease HI. (2001) J Mol Biol 314:
863–871 DOI:10.1006/jmbi.2001.5184) [image online] Available at: https://www.rcsb.org/structure/1jl1
[Accessed 25 November 2019]. This file is licensed under the Creative Commons CC0 1.0 Universal (https://creativecommons.org/publicdomain/zero/1.0/).]
Which level(s) of protein structure is/are shown?
A. Alpha helix only
B. Quaternary only
C. Primary and secondary
D. Secondary and tertiary
[1]
D
This question did not discriminate well, as many students answered that both primary and secondary structures are shown in the diagram. The diagram clearly shows secondary and tertiary structure. The stem of the question indicates the protein had only one polypeptide ruling out quaternary structure. The sequence of amino acids is not shown in the diagram making D the only correct response.
