Micro Lec 6

Front 1

What is the designation +1 and what does it mean?

Back 1

It is the reference of the first nucleotide added to RNA during transcription

Front 2

What is the first factor of RNA polymerase to attatch to the promoter and directs the holoenzyme to the promoter?

Back 2

Sigma

Front 3

How many factors make up RNA polymerase?

Back 3

5 (sigma, two alphas, and two betas)

Front 4

What is another term for constitutively expressed genes?

Back 4

housekeeper genes

Front 5

A repressor blocking the promoter sequence is an example of (positive or negative regulation)?

Back 5

Negative

Front 6

Why is turning off lactose metabolism in the presence of glucose favorable to the bacterium?

Back 6

because it wastes too much energy to break down lactose into a usable energy

Front 7

What two carbohydrates is lactose broken down into?

Back 7

galactose and glucose

Front 8

What does LacZ encode?

Back 8

B-galactosidase

Front 9

What does LacY encode?

Back 9

B-galactosidase permease

Front 10

What does LacA encode?

Back 10

B-galactosidase transacetylase

Front 11

What does LacI encode?

Back 11

repressor protein (on annother gene ___ NOT part of the lac operon)

Front 12

What does LacO encode?

Back 12

operator

Front 13

What does LacP encode?

Back 13

Promoter

Front 14

In the presence of glucose LacI is (ON or OFF)?

Back 14

ON (repressor protein is being transcribed)

Front 15

When lactose is present, it acts as a(n) _________ to the lac operon?

Back 15

Inducer

Front 16

This substance inactivate the repressor protein AND induces the lac operon?

Back 16

Lactose/allolactose

Front 17

What three genes are part of the lac operon?

Back 17

Z, Y, A

Front 18

When glucose in cells is high cAMP levels (increase or decrease)?

Back 18

Decrease (inhibited)

Front 19

Explain catabolite repression?

Back 19

Actually a lack of activation (still positive regulation); In low glucose > cAMP is high > cAMP binds CAP > activates trasncription

Front 20

What is CAP (activator or repressor)?

Back 20

Activator ( in low glucose, high cAMP binds to it and causes activation of transcription)

Front 21

What are uninducible mutants?

Back 21

mutants that cannot be expressed at all

Front 22

What are constitutive mutants?

Back 22

continuosly expressed (do not respond to regulation)

Front 23

The repressor (lacI) is a trans or cis- acting agent?

Back 23

Trans (different gene)

Front 24

What is cis-dominance?

Back 24

one gene affects the genes next to it (lacO is dominant for Z,Y,A)

Front 25

What happens if the lacI gene is knocked out (inactivated lacI-)?

Back 25

lac operon is constitutively expressed (repressor cannot bind)

Front 26

What happens if the lacP gene is mutated (lacP-), is that (constitutive or uninducible)

Back 26

Uninducible (lac operon is nonfunctional)

Front 27

What happens if a mutation occurs which prevents the repressor from binding the inducer (lacIs)?

Back 27

Then the repressor will always be bound to the promoter and transcription of the lac operon cannot occur (uninducible)

Front 28

What are the two major types of terminator sequences?

Back 28

rho-dependant and rho-independent

Front 29

An mRNA with a large G/C base pair region and a run of Uracils at the end is an example of (Rho-dependant or Rho-independent)?

Back 29

Rho-independent

Front 30

In tryptophane biosynthesis what forms (rho-independent 3/4 or pre-emptor 2/3) whn Trp is low?

Back 30

Pre-emptor 2/3

Front 31

When Trp is low in abundance, why does the RNA polymerase stall at site 1, causing the formation of the pre-emptor?

Back 31

RNA polymerase is waiting on Trp charged tRNA (this allows site 2 and 3 to form preventing termination)

Front 32

What is attenuation?

Back 32

The premature termination of transcription of operonsfor amino acid biosynthesis

Front 33

What is the ribosomal binding site upstream of AUG start sequence called?

Back 33

Shine Delgarno Sequence

Front 34

T/F antisens RNA can result in both positive and negative control

Back 34

TRUE;

Front 35

When antisense RNA binds the shine-delgarno sequence, what results?

Back 35

Negative control (Ribosome cannot bind the shine-delgarno sequence and start translation)

Front 36

How can antisense RNA result in positive translational control?

Back 36

If it binds to the untranslated 5' region preventing formation of a secondary structure that blocks the shine-delgarno sequence

Front 37

Where can antisense RNA come from?

Back 37

Either from the complemetn strand (completely complimentary) or from another genetic location (not completely complimentary

Front 38

What can the ompF mRNA be regulated by?

Back 38

Antisense RNA (via micF mRNA antisense RNA ---negative regulation)

Front 39

What is ompF?

Back 39

outer membrane protein that permits the passive diffusion of small hydrophilic molecules into the periplasm

Front 40

Alpha-toxin expression in Staphylococcus Aureus is an example of (antisense inhibition, antisense activation, repression)?

Back 40

Antisense activation

Front 41

What mRNA relieves the shine delgarno site and allows RNA polymerase to bind and translate alpha-toxin?

Back 41

RNAIII

Front 42

What is LexA?

Back 42

transcriptional repressor (controls the genes involved in DNA repair; recA, uvrA, uvrB, uvrC

Front 43

What cleaves LexA repressor and induces DNA repair mechanisms?

Back 43

RecA (senses single stranded DNA damage)

Front 44

Induction of DNA repair mechanisms by RecA cleaving LexA repressor is an example of what kind of regulatory control? (transcriptional, translational, post-translational)?

Back 44

Post-translational

Front 45

Explain the two-component system of bacterial signal transduction?

Back 45

Inputs are sensed by a membrane bound histidine kinase > autokinase with ATP > phosphorylates the response regulator (N-terminal domain) > output domain (c-terminal) > binds DNA and induces change