Transcription of Virulence Genes

Question 1

Virulence Gene Organization-How do bacteria organize their genes?

Answer 1

bacteria generally organize their genes in MULTICISTRONIC OPERONS

Question 2

Virulence Gene Organization-What is a cistron??

Answer 2

CISTRON (STRUCTURAL GENE) is a sequence of DNA that encodes a polypeptide

• 2 cistrons=POLYcistron
• eukaryotes mostly monocistronic

Question 3

Virulence Gene Organization-What is an operon??

Answer 3

OPERON is a unit of transcription that includes MORE THAN ONE CISTRON

Question 4

Virulence Gene Organization-What is multicistronic mRNA??

Answer 4

MULTICISTRONIC MRNA is the mRNA that results form transcription of a multicistronic operon

Question 5

Process of Transcription-General

Answer 5

operon–transcription–RNA polymerase
mRNA–translation
protein

Question 6

Process of Transcription-Players

Answer 6

typical operon includes: a PROMOTER, an OPERATOR, CISTRONS and a TERMINATOR

Question 7

Process of Transcription-Who dat, who dat, RNAP?!

Answer 7

RNA Polymerase (RNAP)=biological machine that transcribes DNA into mRNA

Question 8

Process of Transcription-who is the PROMOTER??

Answer 8

Promoter is the site at which RNAP BINDS

Question 9

Process of Transcription-SIGMA theta psi epsilon kappa

Answer 9

SIGMA is a subunit of RNAP that specifically recognizes and binds the promoter

Question 10

Process of Transcription-Who CLOSED the COMPLEX

Answer 10

the product of the RNAP/DNA interaction

Question 11

Process of Transcription-Cant wait for OPEN COMPLEX

Answer 11

once bound, RNAP causes the double strand of DNA to open-have template and NON-template

Question 12

Process of Transcription-What’s the point of strand separation??

Answer 12

strand separation allows synthesis of mRNA strand complementary to DNA sense strand

Question 13

Process of Transcription-How does it proceed?

Answer 13

Transcription proceeds elongating the mRNA until RNAP encounters a termination signal. Sigma factor falls off when RNAP clears the promoter

Question 14

Regulation of Transcription Initiation-Wither

Answer 14

Cells regulate transcription primarily at its initiation

Question 15

Regulation of Transcription Initiation-Why or Why Not??

Answer 15

**ability of RNAP to bind the promoter determines…the FREQUENCY of initiation…the setting of which determines the decision to initiate or not

Question 16

Regulation of Transcription Initiation-Two types of regulator proteins control that ability

Answer 16

REPRESSOR and ACTIVATOR

Question 17

Regulation of Transcription Initiation-REPRESSOR

Answer 17

REPRESSOR binds the OPERATOR

Question 18

Regulation of Transcription Initiation-ACTIVATOR

Answer 18

ACTIVATOR interacts with RNAP, increasing the ability of RNAP to bind the promoter. CO-ACTIVATOR (cAMP) binds activator INCREASING ACTIVATOR binding affinity.

Question 19

Regulation of Transcription Initiation-Where is the OPERATOR

Answer 19

The operator is a site located close to OR overlapping the promoter. OVERLAP prohibits binding of RNAP to promoter. INHIBITORY BEHAVIOR is called STERIC HINDRANCE.

Question 20

Regulation of Transcription Initiation-Who is the INDUCER?!

Answer 20

INDUCER (ex: lactose) is a small molecule that binds the REPRESSOR, changing the conformation of that protein so that it can no longer bind DNA (decreases REPRESSOR AFFINITY)

Question 21

Glucose/cAMP (relation)ship

Answer 21

as [glucose] DECREASES [cAMP] INCREASES. With glucose present don’t need lac operon.

Question 22

Induction deets

Answer 22

glucose absent/cAMP present. lactose (inducer) present

Question 23

Activators, Repressors, STABILITY

Answer 23

• Activators INCREASE stability
• Repressors DECREASE stability
• the probability of transcription initiation increases as the stability of the closed complex increases

Question 24

What’s the C-spot?

Answer 24

C=cAMP CRP binding site, lacR expressed constitutively

Question 25

What does cAMP-CRP do?

Answer 25

recruits RNAP to the promoter