Chapter 14: Regulation of Bacterial Cellular Processes

Question 1

Constitutive genes (housekeeping genes)

Answer 1

• Genes that encode enzymes of the central metabolic
  pathway
• Cell needs constant supply of active enzymes
• They are regularly transcribed and translated

Question 2

Some enzymes only needed during specific
conditions/environments

Answer 2

gene expression is → regulated

Question 3

Regulation of gene expression can be done through:

Answer 3

• Transcriptional: initiation or elongation
• Translational

Question 4

Alter activity of → proteins

Answer 4

• Posttranslational modification

Question 5

Nutrient availability in the environment changes the gene
expression of a cell

Question 6

β-galactosidase

Answer 6

hydrolyzes lactose into galactose and
glucose

Question 7

Absence of lactose

Answer 7

3 β-galactosidase molecules

Question 8

Presence of lactose

Answer 8

3,000 β-galactosidase molecules

Question 9

Inducer

Answer 9

small effector molecule that stimulates gene
expression

Question 10

Inducible genes

Answer 10

genes that encode inducible enzymes
* Required only when their substrate is → available

Question 11

Corepressor

Answer 11

small effector molecule

Question 12

Repressible genes

Answer 12

genes for enzymes involved in biosynthetic pathways
* Generally, these enzymes are
always present
* Unless the end product in the
biosynthetic pathway is available

Question 13

Initiation occurs when sigma subunit of RNA polymerase
positions the core enzyme at a →

Answer 13

promoter

Question 14

Transcription factors

Answer 14

regulate transcription → initiation
* DNA binding domain interacts with the → promoter

Question 15

Negative control

Answer 15

Repressor protein binds to DNA
* Binding operator inhibits transcription initiation by
blocking RNA polymerase from binding

Question 16

Positive control

Answer 16

Activator protein binds to DNA
* Binding to activator binding sites upstream of
promoter encourages RNA polymerase to bind

Question 17

Repressor proteins bind onto the DNA at the

Answer 17

operator

• Overlaps or is downstream from the gene → promotor
• Blocks the binding or movement of RNA polymerase

Question 18

Activator proteins bind to

Answer 18

activator-binding sites

• These are found upstream of the promotor
• Enables RNA polymerase to bind

Question 19

Enzymes of catabolic pathway
are only needed (increased
mRNA synthesis) when their
preferred substrate is →

Answer 19

available

Question 20

Enzymes are not synthesized
when their substrate is →

Answer 20

absent

Question 21

Bacteria have polycistronic mRNA that carriers multiple
genes that are transcribed and translated →

Answer 21

together

Question 22

structural genes

Answer 22

genes that code for nonregulatory polypeptides (enzymes) that are all lined up together on DNA

Question 23

Operon

Answer 23

structural gene, promotor and operator, or
activator-binding site

Question 24

Lactose Operon

Answer 24

Three structural genes coding for lactose uptake and
metabolism

Question 25

What three structural genes coding for lactose uptake and metabolism?

Answer 25

lacZ, lacY, and lacA

Question 26

lacZ codes for

Answer 26

-galactosidase hydrolyzes lactose into galactose and glucose

Question 27

lacY codes for

Answer 27

lactose permease – membrane transporter that bring lactose into the cell

Question 28

lacA codes

Answer 28

for transacetylase