Question

A model of how DNA is organized to form genes is shown here. What likely explains how DNA within a single gene can create multiple phenotypes within the same organism that contains the same genome in each cell? (Choose 2)
Responses
A Differential timing of when genes are expressed can produce different phenotypes.Differential timing of when genes are expressed can produce different phenotypes.
B Differential splicing of exons after intro removal can produce multiple phenotypes.Differential splicing of exons after intro removal can produce multiple phenotypes.
C Different numbers of genes within the DNA molecule can exist within the same organism.Different numbers of genes within the DNA molecule can exist within the same organism.
D Varying quantities of DNA in each cell results in multiple phenotypes from the same genome.Varying quantities of DNA in each cell results in multiple phenotypes from the same genome.
E Different organelles can be used to translate the same gene region, which results in unique proteins and phenotypes.

Answer 1

Correct choices: A and B.

- A is correct: Cells can turn the same gene on or off at different times or in different tissues, producing different phenotypes.
- B is correct: Alternative splicing of exons after intron removal makes multiple mRNA/protein isoforms from one gene.

C, D, and E are not good explanations in this context:
- C: an organism’s cells don’t normally have different numbers of genes in the same genome.
- D: the question assumes the same genome per cell; varying DNA quantity is not the usual explanation.
- E: nuclear genes aren’t translated by different organelles to produce distinct proteins in the way implied.