Chapter 20

Question 1

A signal molecule that, when bound to a regulatory protein, produces an increase in the expression of a given gene.

Answer 1

inducer

Question 2

The inhibition of the expression of genes required for the metabolism of other sugars in the presence of glucose.

Answer 2

catabolite repression:

Question 3

A protein that inhibits transcription by binding both the RNA polymerase and a repressor or repressors, without binding the DNA directly.

Answer 3

corepressor

Question 4

A process for the regulation of expression of a bacterial operon in which transcription begins but is halted before transcription of the operon genes.

Answer 4

transcription attenuation

Question 5

A short sequence near the 5′ end of an RNA that has a specialized targeting or regulatory function.

Answer 5

leader sequence

Question 6

Broadly, a place where transcription is halted. This can occur at the end of a gene (where some termination sequences are also called terminators) or in regulatory sequences preceding some operons (as occurs in transcription attenuation).

Answer 6

terminator

Question 7

A short sequence near the amino terminus of a protein that has a specialized targeting or regulatory function.

Answer 7

leader peptide

Question 8

In bacteria, a coordinated induction of a variety of genes in response to high levels of DNA damage.

Answer 8

SOS response

Question 9

A structured segment of an mRNA that binds to a specific ligand and affects the translation or processing of the mRNA.

Answer 9

riboswitch

Question 10

A repressor that binds to an mRNA, blocking translation.

Answer 10

translational repressor

Question 11

A mechanism for coordinating transcriptional activity in bacteria with the levels of amino acids available in the cell. Triggered by the binding of uncharged tRNAs to the ribosome, the stringent response directs the cellular machinery toward amino acid synthesis rather than growth and reproduction.

Answer 11

stringent response

Question 12

A bacterial protein (RelA) recruited to a ribosome when an uncharged tRNA binds. Stringent factor catalyzes the formation of guanosine tetraphosphate (ppGpp), which binds RNA polymerase, reducing transcription from rRNA and tRNA genes and increasing transcription from biosynthetic genes.

Answer 12

stringent factor

Question 13

An effector molecule synthesized in a cell in response to an external signal (first messenger) such as a hormone.

Answer 13

second messenger