Transcription factors account for a greater proportion of the proteome in a fetus compared to a 20-year-old because
A) many cells have already died in a 20-year-old.
B) a fetus does not yet need many of its proteins.
C) cells are actively differentiating and many structures are forming in a fetus.
D) an adult can carry out more activities than can a fetus.
E) the 20-year-old can consciously activate his or her transcription factors.

Question

Quizplus · Accepted Answer

During fetal development, many cells are actively differentiating into various cell types and forming complex structures. Transcription factors are key regulators of gene expression during development, so their higher abundance in fetal cells may be required for proper differentiation and tissue formation. In contrast, many of the cell types in a 20-year-old are already established, and fewer transcription factors may be needed to maintain the expression of the genes required for their function.

Transcription Factors Account for a Greater Proportion of the Proteome