Question

polypeptide: val — his — leu — thr
the table shows the mrna codons that code for the amino acids present in the polypeptide.

amino acid

mrna codons

----

----

leucine

cuu cuc cua cug uua uug

histidine

cau cac

threonine

acu acc aca acg

valine

guu guc gua gug

from which mrna segment was the polypeptide translated?○ gtg cat ctg act○ gug cau ctg act○ gug cau cug acu○ cac gua gac uga

Explanation:

Step1: Match val to mRNA codon

Valine (val) has codons GUU, GUC, GUA, GUG.

Step2: Match his to mRNA codon

Histidine (his) has codons CAU, CAC.

Step3: Match leu to mRNA codon

Leucine (leu) has codons CUU, CUC, CUA, CUG, UUA, UUG.

Step4: Match thr to mRNA codon

Threonine (thr) has codons ACU, ACC, ACA, ACG.

Step5: Validate full mRNA sequence

Combine codons in order: val (GUG) → his (CAU) → leu (CUG) → thr (ACU), forming GUG CAU CUG ACU. Eliminate options with DNA bases (T) or incorrect codons.

Answer:

○ GUG CAU CUG ACU