A Levels Biology (9700)•9700/13/M/J/23
Explanation
mRNA Codon Identification in Translation
Steps:
- Locate the mRNA strand in the ribosome diagram, read 5' to 3'.
- Identify position S as the codon in the A-site.
- Note the bases at S: guanine, adenine, uracil.
- Confirm GAU codes for aspartic acid, pairing with tRNA.
Why C is correct:
- GAU is the standard RNA codon for aspartic acid per the genetic code.
Why the others are wrong:
- A. CUA codes for leucine, not matching the diagram's amino acid.
- B. CAT uses thymine (DNA base), invalid for mRNA.
- D. GAT uses thymine (DNA base), invalid for mRNA.
Final answer: C
Topic: Protein synthesis
Practice more A Levels Biology (9700) questions on mMCQ.me