CHAPTER 10

Regulation of Gene Expression in Bacteria and Their Viruses

CHAPTER 10

Regulation of Gene Expression in Bacteria and Their Viruses

Copyright 2008 © W H Freeman and Company

CHAPTER OUTLINE10.1 Gene regulation

10.2 Discovery of the lac system: negative control

10.3 Catabolite repression of the lac operon: positive control

10.4 Dual positive and negative control: the arabinose operon

10.5 Metabolic pathways and additional levels of regulation: attenuation

10.6 Bacteriophage life cycles: more regulators, complex operons

10.7 Alternative sigma factors regulate large sets of genes

Regulatory proteins control transcription

Figure 10-2

Allosteric effectors bind to regulatory proteins

Figure 10-3

Repressor protein controls the lac operon

Figure 10-4

Lactose is broken down into two sugars

Figure 10-5

The lac operon is transcribed only in the presence of lactose

Figure 10-6a

The lac operon is transcribed only in the presence of lactose

Figure 10-6b

Structure of IPTG

Figure 10-7

Table 10-1

Operators are cis-acting

Figure 10-8

Table 10-2

Repressors are trans-acting

Figure 10-9

Table 10-3

The repressor contains a lactose-binding site

Figure 10-10

RNA polymerase contacts the promoter at specific sequences

Figure 10-11

The operator is a specific DNA sequence

Figure 10-12

Glucose levels control the lac operon

Figure 10-13

Glucose levels control the lac operon

Figure 10-13a

Glucose levels control the lac operon

Figure 10-13b

Many DNA binding sites are symmetrical

Figure 10-14

Binding of CAP bends DNA

Figure 10-15

CAP and RNA polymerase bind next to each other

Figure 10-16

Negative and positive control of the lac operon

Figure 10-17

Negative and positive control of the lac operon

Figure 10-17a

Negative and positive control of the lac operon

Figure 10-17b

Negative and positive control of the lac operon

Figure 10-17c

Repression and activation compared

Figure 10-18

Repression and activation compared

Figure 10-18a

Repression and activation compared

Figure 10-18b

Map of the ara operon

Figure 10-19

AraC serves as an activator and as a repressor

Figure 10-20

Gene order in the trp operon corresponds to reaction order in

the biosynthetic pathway

Figure 10-21

The trp mRNA leader sequence contains an attenuator region

and two tryptophan codons

Figure 10-22

Abundant tryptophan attenuates transcription of the trp operon

Figure 10-23

Leader peptides of amino acid biosynthesis operons

Figure 10-24

The life cycle of bacteriophage

Figure 10-25

Phage genome is organized for coordinate control

Figure 10-26

Figure 10-27

The lysogenic-versus-lytic cycle is determined by repressoroccupancy on the OR operators

Helix-turn-helix is a common DNA-binding motif

Figure 10-28

Amino acid side chains determine the specificity of DNA binding

Figure 10-29

factors control clusters of unlinked genes

Figure 10-30a

factors control clusters of unlinked genes

Figure 10-30b