Microbiolgy Lecture 12

Question 1

What are the mechanisms of gene regulation?

Answer 1

Constituitive
Inducible
Repressible

Question 2

What’s a constitutive enzyme?

Answer 2

An enzyme that is always produced, gene expression is always on

Question 3

What is an repressible enzyme?

Answer 3

An enzyme that is normally produced, but can be turned off when not needded

Question 3

What is a inducible enzyme?

Answer 3

An enzyme that is not always produced, but can be turned on when needed

Question 4

What are operons?

Answer 4

A cluster of multiple genes that are transcribed together, but translated seperatedly

Question 5

What turns on gene expression?

Answer 5

Regulatory protein

Question 6

What is a lac operon

Answer 6

Contains genes necessary to break down lactose

Question 7

What is lac operon consider and why?

Answer 7

It’s considered inducible because it’s usually turned off, but can be turned on in presence of lactose and absence of glucose

Question 8

What are the four genes in the lac operon?

Answer 8

Permease, B galactosidase, acetylase, and regulatory protein

Question 9

During diphasic growth, E coli prefers to metabolize .. and then switch to …

Answer 9

It prefers to metabolize glucose and when no more glucose is present, switch to lactose

Question 10

Why is there a pause in the Diphasic growth?

Answer 10

To turn lac operon on

Question 11

What are riboswitches?

Answer 11

They regulate gene expression after transcription through binding of a ligand/ binding of ligand can hide or reveal Shine Dalgarno

Question 12

What are sRNas

Answer 12

short noncoding RNAS that regulate translation

- They increase/decrease translation of a transcript

Question 13

What two items regulate gene expression on a global scale

Answer 13

• Alternative sigma factor

- Secondary Messagers

Question 14

Secondary Messagers involve what?

Answer 14

cAMP and ppGpp

Question 15

What is cAMP?

Answer 15

Made when ATP levels are low/ increases expression of genes necessary for breaking down sugars

Question 16

What is ppGpp

Answer 16

Made when amino acid levels are low/ Increases genes necessary to provide amino acids

Question 17

In the absence of cAMP, what happens?

Answer 17

CAP does not bind the promoter/Transcription occurs at low rate

Question 18

In the presence of cAMP, what happens?

Answer 18

CAP binds the promoter and increases RNA polymerase activity

Question 19

What do cAMP CAP complex do?

Answer 19

They stimulate RNA polymerase activity and increases RNA synthesis

Question 20

However, even in the presence of cAMP CAP, what happens?

Answer 20

• RNA synthesis is blocked

Question 21

Talk about Individual behavior

Answer 21

Bacteria has individual behavior and act alone

Question 22

Talk about Group behavior bacteria

Answer 22

Group Behavior leads to a bigger population, higher concentration, and leads to group behavior as bacteria communicate with one another and exhibit new group behaviors

Question 23

When quorum has been reached, what happens?

Answer 23

Genes for a certain behavior are turned on

Question 24

The lac operon is an example of .. gene expression

Answer 24

Inducible gene expression

Question 25

What does alolactose do?

Answer 25

Bind to represor and prevent it from binding to lacO

Question 26

What do transcriptional repressors do?

Answer 26

Block transcription by preventing RNA polymerase from activating transcription

Question 27

Lac operons are turned on when?

Answer 27

In the presence of lactose

Question 28

Lac Operon does what

Answer 28

Encodes proteins necessary for metabolizing lactose