Chapter 5c - Regulation of Gene Expression

Question 1

virtually every cell in your body contains a __ __ of genes

Answer 1

complete set

Question 2

genes are not all __ __ in every tissue

Answer 2

turned on

Question 3

each cell in the body expresses only how many genes at any time

Answer 3

small subset

Question 4

during development, what do different cells express

Answer 4

different set of genes in precisely regulated fashion

Question 5

where does gene regulation primarily occur

Answer 5

transcription

Question 6

a given cell transcribes only a __ __ of genes and not others

Answer 6

specific set

Question 7

Gene products should be released at the ….

Answer 7

right time, right place, right amounts

Question 8

Gene regulation in prokaryotes are mainly for

Answer 8

1. growth
2. response to environment

Question 9

• cluster of genes that are transcribed together to give a single messenger RNA (mRNA) molecule, which therefore encodes multiple proteins
• cluster of genes encoding related enzymes that are regulated together

Answer 9

operon

Question 10

who coined the term operon

Answer 10

1. Francis Jacob
2. Jacques Monod
   1961

Question 11

where do operons mostly occur

Answer 11

prokaryotes

Question 12

Two Categories of Gene Control

Answer 12

1. Negative regulation
2. Positive regulation

Question 13

• an inhibitor (repressor) is present in the cell that keeps transcription turned off
• an anti-inhibitor (inducer) is needed to turn the system on

Answer 13

negative regulation

Question 14

inhibitor

Answer 14

repressor

Question 15

anti-inhibitor

Answer 15

inducer

Question 16

an effector molecule which may be a protein, small molecule or a molecular complex activates a promoter

Answer 16

positive regulation

Question 17

Two types of Proteins in Bacterial Cells

Answer 17

1. Structural proteins
2. Regulatory proteins

Question 18

do not regulate transcriptio

Answer 18

structural proteins

Question 19

ex. of structural proteins

Answer 19

1. enzymes
2. membrane proteins
3. ribosomal components

Question 20

help sense environment and regulate rate of transcription of structural genes by binding to DNA

Answer 20

regulatory proteins

Question 21

• contains genes involved in lactose metabolism
• It’s expressed only when lactose is present and glucose is absent

Answer 21

lactose (lac) operon

Question 22

parts of the lac operon

Answer 22

• P (promoter)
• O (operator)
• Z
• Y
• A

Question 23

structural loci of lac operon

Answer 23

• Z
• Y
• A

Question 24

Z is the structural gene for what?

Answer 24

beta-galactosidase

Question 25

Y is the structural gene for what?

Answer 25

beta-galactosidase permease

Question 26

A is the structural gene for what?

Answer 26

beta-galactosidase transacetylase

Question 27

lactose is absent, __ __, __ __

Answer 27

- repressor active - operon off

Question 28

lactose present, __ __, __ __

Answer 28

- repressor inactive - operon on

Question 29

what type of promoter is lac operon

Answer 29

weak

Question 30

expression level of lac operon

Answer 30

basal

Question 31

binding site of lac operon

Answer 31

-60 region

Question 32

name of binding site of lac operon

Answer 32

CRP (cAMP receptor protein) site

Question 33

CRP

Answer 33

cAMP receptor protein

Question 34

effect of cAMP-CRP on gene expression

Answer 34

enhancing effect

Question 35

cAMP

Answer 35

cyclic adenosine monophosphate

Question 36

what are the operons repressed in the presence of glucose

Answer 36

- maltose - sorbitol - lactose - arabinose - galactose

Question 37

what is needed to turn on the sugar-metabolizing operons

Answer 37

cAMP

Question 38

when glucose levels are low, __ is produced. It attaches to __, allowing it to bind DNA. Then it helps ____ bind to the promotor, resulting in high levels of transcription

Answer 38

- cAMP - CRP - RNA polymerase

Question 39

in low glucose, what is the rate of transcription

Answer 39

high

Question 40

when glucose levels are high, __ __ is made. __ can't bind to DNA without it, so transcription occurs only at a low level

Answer 40

- no cAMP - CRP

Question 41

in high glucose, what is the rate of transcription

Answer 41

low

Question 42

cAMP formation

Answer 42

ATP --> (adenylyl cyclase) cAMP + Ppi

Question 43

how does glucose reduce levels of cAMP

Answer 43

inactivating adenylate cyclase

Question 44

one of the constitutive genes expressed at the basal level

Answer 44

tryptophan (trp) operon

Question 45

gene that is transcribed continually

Answer 45

constitutive gene

Question 46

what does the trp operon produce

Answer 46

polypeptides that make up enzymes of tryptophan synthesis

Question 47

tryptophan absent, __ __, __ __

Answer 47

- repressor inactive - operon on

Question 48

tryptophan present, __ __, __ __

Answer 48

- repressor active - operon off

Question 49

eukaryotic gene regulation

Answer 49

epigenetic mechanisms

Question 50

highly condensed, gene-poor, and transcriptionally silent

Answer 50

Heterochromatin

Question 51

less condensed, gene-rich, and more easily transcribed

Answer 51

Euchromatin

Question 52

regions with high transcriptional activity are loosely packed

Answer 52

acetylation

Question 53

regions with low or no transcriptional activity are densely packed

Answer 53

methylation

Question 54

What are the Epigenetic Mechanisms

Answer 54

1. acetylation 2. methylation

Question 55

transcriptional activation

Answer 55

histone acetylation

Question 56

gene silencing

Answer 56

histone deacetylation

Question 57

DNA coiled = ?

Answer 57

turned OFF

Question 58

what does acetylation unfold

Answer 58

chromatin

Question 59

histones that unfold chromatins

Answer 59

H3 and H4 histones

Question 60

favors condensation and leads to inactive DNA once CH3 is passed generationally

Answer 60

methylation of nucleotides