Ch12

Question 1

constitutive expression

Answer 1

when a gene is transcribed constantly

Question 2

inducible expression

Answer 2

gene is transcribed only when needed (can be turned off or on)

Question 3

How can enzymes be regulated? briefly explain each.

Answer 3

allosteric inhibition - alteration of enzyme’s structure in order to stop function
covalent modification - methylation/ phosphorylation in order to control it (not as efficient as transcription regulation BUT quicker)

Question 4

consensus sequence

Answer 4

the optimal promoter sequence that RNA polymerase binds to

Question 5

What are operons? Why are they important?

Answer 5

a series of genes that share a promoter and regulatory elements; allows the cell to conserve energy through control of transcription

Question 6

What is the lac operon? Describe the Structural genes.

Answer 6

A series of genes dedicated to the metabolism/ transport of lactose

made up of lacZ- creates beta gal/ breakdown of lactose
lacY - creates permease/ transport of lactose in the cell
lacA - makes beta gal transacetylase (currently unknown why)

Question 7

Completely describe a negative control relative to an operon. In the lac operon, what prevents the repressor from binding to the operator

Answer 7

regulatory mechanisms that block transcription via a repressor (blocks operon)

effectors are small molecules that have the ability to influence a repressor’s behavior

inducers - (a type of effector) repressor proteins that prevent binding between repressor and operator

corepressors - strengthen the binding between the repressor and operator

allolactase

Question 8

Completely describe a positive control relative to an operon.

Answer 8

involved with activators that lead to increased transcription (activators factor into this)