Exam 16: Regulation of Gene Expression

The outer shell of a virus is called a

In a hypothetical bacterial operon, genes A, C, and D are expressed when "substance r" is present but not when it is absent.Mutations in gene A cause protein 1 not to be produced, but they only affect production of protein 1.Mutations in gene C cause protein 2 not to be produced.Mutations in gene D cause protein 3 not to be produced.Gene B, which has been shown to be near the other genes, does not code for a protein.Mutations in gene B cause genes A, C, and D to be expressed all the time regardless of the presence or absence of substance r.Gene E produces protein 4.Mutations in gene E (which is not near A, B, C, or D) cause genes A, C, and D to be expressed all the time regardless of the presence or absence of substance r.What is the role of gene B?

Cro is a bacteriophage λ protein that represses transcription of cI but promotes expression of genes that encourage the lytic cycle.cI protein represses Cro transcription but promotes expression of genes that encourage lysogeny.If the environment experienced by bacteriophage λ deteriorates, the change will most likely _______ the lifespan of cI protein.This result will have the effect of _______.

Which of the following is a carrier protein?

Regulatory sequences in bacterial operons