21: gene regulation

Question 1

what is gene expression?

Answer 1

when a gene is transcribed and translated to make a protein or polypeptide (sometimes only tRNA or rRNA are made)

Question 2

when does regulation of gene expression take place? what is this considered?

Answer 2

transcription; energy saving

Question 3

what leads to a gene being expressed or turned off?

Answer 3

an environmental cue

Question 4

what are examples of an environmental cue?

Answer 4

nutrient, chemical, or element

Question 5

what is the cue for P. shigelloides to start making HugA?

Answer 5

lack of free iron in environment

Question 6

what is a protein that stops transcription?

Answer 6

repressor

Question 7

what is a protein that stimulates transcription?

Answer 7

activators

Question 8

what interacts w repressor and activators?

Answer 8

environmental cues

Question 9

what is needed to regulate a strong promoter? how?

Answer 9

repressor, by keeping RNA Pol from binding to promoter or keeping it from moving down the DNA

Question 10

repressors are often present as what?

Answer 10

dimers or tetramers

Question 11

where does a repressor bind to?

Answer 11

operator

Question 12

where can the operator be?

Answer 12

on the promoter or downstream of the promoter

Question 13

what operator is present in an iron-regulated gene like hugA?

Answer 13

Fur box

Question 14

a series of genes that encode proteins involved in transport and breakdown of lactose

Answer 14

lac operon

Question 15

is the operator DNA, protein, or RNA?

Answer 15

DNA, it’s part of a gene

Question 16

what is the repressor in the lac operon?

Answer 16

LacI

Question 17

protein that helps a weak promoter bind more strongly to RNA Pol

Answer 17

activators

Question 18

where do activators bind? where are they located?

Answer 18

activator binding sites (specific DNA sequence); upstream of promoter

Question 19

elements or compounds (not proteins) that bind to regulatory proteins; environmental cues that tell regulatory proteins what to do

Answer 19

inducers and co-repressors

Question 20

binds to a regulatory protein and allows transcription

Answer 20

inducer

Question 21

what regulatory proteins can an inducer bind to?

Answer 21

an activator or a repressor (in both cases allows transcription)

Question 22

compounds/ elements that bind to a repressor and cause it to get on operator; helps repress

Answer 22

co-repressor

Question 23

where does dna binding domain of a repressor bind to on the DNA?

Answer 23

operator

Question 24

where does dna binding site of an activator bind to on DNA?

Answer 24

activator binding site