Genomics and population genetics

Question 1

What is gene regulation?

Answer 1

Process where genes required by particular cells are switched on and remaining unnecessary genes are turned off

Question 2

When can gene regulation occur?

Answer 2

At any point in the journey from DNA to final protein product

Question 3

Types of transcriptional regulation

Answer 3

Positive Transcriptional Regulation

Negative Transcriptional Regulation

Question 4

Positive Transcriptional Regulation

Answer 4

Activator protein must be present in order for the recruitment of RNA polymerase complex to occur

Question 5

Negative Transcriptional Regulation

Answer 5

RNA polymerase will be blocked by the presence of a repressor protein, thereby inhibiting transcription

Question 6

What occurs in the lac operon when there is no lactose?

Answer 6

the repressor protein is unable to bind to the operator, and the promoter recruits the RNA polymerase complex and transcription occurs.

Question 7

What happens when there is enough glucose present?

Answer 7

the lac operon will not activate because glucose is the preferred source of energy

Question 8

Role of cyclic AMP in the lac operon

Answer 8

A small molecule present in high amounts when glucose levels are low so it acts as a signal for glucose concentration

Question 9

What happens to the levels of cAMP when there is low glucose in cells

Answer 9

there will be higher cAMP levels. this forms a complex with CRP (cAMP complex receptor) upstream of the promotor sequence. binding of this CRP-cAMP complex to the lac promoter is necessary for the recruitment of the RNA polymerase

Question 10

When there are low cAMP levels and high glucose, what happens to the lac operon?

Answer 10

cAMP complex receptor is unable to bind to the promoter, therefore RNA polymerase cannot function

Question 11

Repressible operon

Answer 11

gene expression pathway that will turn off when there is sufficient levels of the protein/enzyme in the cell

Question 12

inducible operon

Answer 12

gene expression which will turn on when a molecule is detected

Question 13

repressor protein

Answer 13

molecule that inhibits the expression of a gene by binding to the operator and preventing RNA polymerase from binding

Question 14

operon

Answer 14

a set of adjacent structural genes arranged under a common promoter and regulated by a common operator

Question 15

activator protein

Answer 15

proteins that increases gene transcription of a set of genes

Question 16

transcription factors

Answer 16

proteins that help switch genes on or off

Question 17

operator

Answer 17

binding site for a repressor protein

Question 18

polycistronic mRNA

Answer 18

single molecule of mRNA that is formed by the transcription of a group of functionally related genes located next to one another along bacterial DNA

Question 19

constitutive gene expression

Answer 19

expression of a gene that occurs continuously

Question 20

inducible gene expression

Answer 20

genes that are regulated and must be switched on or off