Cell growth depends on the transcription of genes and translation into protein - Scottish Highers Biology - Question 2 - 2022

The diagram indicates that more than one polypeptide (polypeptides X and Y) is produced from the primary mRNA transcript, which suggests that alternative splicing has taken place.

Alternative RNA splicing is a process whereby different exons from the primary mRNA transcript are retained or excluded, resulting in the formation of multiple mature mRNA transcripts. This allows for the production of different proteins from a single gene.

Ribosomes contain rRNA, which would incorporate the radioactive uracil present in the growth medium during the synthesis of rRNA. Additionally, as mRNA is translated at the ribosome, the uracil from the mRNA would also be detectable, confirming its presence in the molecules synthesized.