Although the Expression of Most Genes Is Tightly Regulated, Some

Multiple Choice

Although the expression of most genes is tightly regulated, some genes are expressed at roughly constant rates. Which of the following genes would you predict to be constitutively (constantly) expressed?

A) genes involved in the biosynthesis of the amino acid tryptophan
B) genes involved in the degradation of tryptophan
C) genes involved in the degradation of arabinose, a sugar
D) genes that code for regulatory proteins