Question

Suppose that a scientist deletes the AAUAAA consensus sequence, the poly(A) tail, or the 5' cap from pre‑mRNAs in an mRNA. She then observes the effects on RNA regulation.

Assign each RNA regulation consequence to the type of deletion most likely to result in the consequence.

Answer 1

The absence of the AAUAAA consensus sequence, poly(A) tail, or 5' cap from pre-mRNAs leads to instability and degradation of mRNA, as well as poor translation due to the loss of these crucial regulatory features.

Step-by-step explanation:

Deletions in various regions of pre-mRNA have different effects on RNA regulation. Specifically:

• Deleting the AAUAAA consensus sequence will inhibit the cleavage of pre-mRNA for the addition of the 3' poly(A) tail, leading to instability and potentially preventing the mRNA from being exported to the cytoplasm.
• Removing the poly(A) tail itself will also decrease the stability of the mRNA and affect its half-life in the cytoplasm, which could lead to less protein being produced as the mRNA decays more quickly.
• Deleting the 5' cap removes the protection against exonuclease degradation and the recognition feature needed by the translation machinery to initiate protein synthesis. Consequently, an mRNA lacking the 5' cap would likely be rapidly degraded and poorly translated.

Each of these modifications plays a crucial role in RNA stability and efficient translation regulation, and their absence can result in early degradation or inefficient translation.