EXAM 3 P4

Question 1

DNA binding proteins

Answer 1

carry out transcription
majority function as dimers
most recognize sites in DNA known as inverted repeats. recognize sequences next to and facing each other
specificity

Question 2

repressors

Answer 2

exert negative control
when bound to DNA, they turn the gene off, blocking RNAP access to the promoter
locate the operator

Question 3

example of repression

Answer 3

arginine synthesis

once a lot is present, no more needs to be made so expression of the arginine synthesis enzyme is turned off

Question 4

induction

Answer 4

exerts positive control

when lac is dumped into the growth medium, cells turn on expression of the lac utilization gene

Question 5

arg repressor

Answer 5

acts when it binds to the corepressor of arginine
this allows the repressor to be active and bind to the operator sequence of DNA
this blocks RNAP from effectively using the promoter, preventing transcription

Question 6

lac repressor

Answer 6

binds to the DNA operator, shutting lac genes off
when the corepressor is added, it binds to the repressor, unbinding it from the DNA. polymerase can now carry out transcription

Question 7

inducer

Answer 7

small lac molecule
turns gene expression on
causes the repressor to stop binding

Question 8

corepressor

Answer 8

turn gene expression off causing the repressor to start binding

Question 9

activators

Answer 9

exert positive control

bind next to promoters to increase transcription

Question 10

catabolite repression

Answer 10

glucose grows and becomes exhausted, so lactose growth begins
true for all carbon sources

Question 11

production of cAMP

Answer 11

adenine cyclase enzyme cyclizes phosphate to create cAMP from ATP

Question 12

what is cAMP (cyclic AMP)

Answer 12

an internal signaling molecule for lack of glucose.
as long as glucose is present, cAMP is inhibited
if glucose runs out, cAMP is produced by adenine cyclase

Question 13

cAMP and CRP

Answer 13

cAMP binds to CRP protein and activates transcription

Question 14

CRP (catabolite repression protein)

Answer 14

alone it does nothing, but when cAMP is produced, CRP binds and dimerizes, becoming a functional DNA binding protein.
binds to an activator binding site upstream of promoter
CRP is an activator

Question 15

component 1

Answer 15

a protein called a sensor kinase. it senses an environmental signal (change in temp, pH) and transmits this information to the other protein

Question 16

component 2

Answer 16

response regulator
usually a transcription regulator, so the protein is a repressor or an activator. takes the info from comp 1 and decides what response to take

Question 17

what is the signal transmitted in 2 component regulatory system

Answer 17

phosphorylation or dephosphorylation
takes phosphate from ATP and sticks it to itself. then puts it onto the response regulator. a phosphorylated regulator becomes active

Question 18

spores

Answer 18

the most resistant lifeform on earth

formation requires a large mother cell and a small fore spore

Question 19

sporulation

Answer 19

sigma factor becomes active only in the fore spore. a signal is sent to the mother, activating sigma in the mother spore. the fore spore produces the spore, and the mother cell produces the spores components, but eventually dies

Question 20

mother spores

Answer 20

focus on the outer layers to protect the spore from chemicals
eventually die

Question 21

quorum sensing

Answer 21

allows single celled organisms to function as a population in a coordinated fashion.
can decide when to turn on a specific gene at a certain time
regulates many things like luminescence and biofilm formation

Question 22

autoinducer

Answer 22

small molecule associated with quorum sensing