Chapter 17: Gene Regulation in Eukaryotes

Question 1

Gene Regulation

Answer 1

variation in the level of gene expression under different conditions

Question 2

Transcription factor

Answer 2

broad category of proteins that influence the ability of RNA polymerase to transcribe DNA into RNA

Question 3

General Transcription Factor (GTF)

Answer 3

one of several proteins that are necessary for a basal level of transcription at the core promoter in eukaryotes

Question 4

Regulatory transcription factor

Answer 4

protein or protein complex that binds to a regulatory element and influences the rate of transcription vis RNA polymerase

Question 5

Activator

Answer 5

enhances the rate of transcription by binding to an enhancer sequence

Question 6

Repressor

Answer 6

prevent transcription from occurring by binding to a silencer sequence

Question 7

combination of many factors regulates genes

Answer 7

combinatorial control

Question 8

Modification of ____________ transcription factor proteins can occur in 3 common ways:

Answer 8

Regulatory
1. Binding of small-effector molecule
2. Protein-protein interactions
3. Covalent modifications

Question 9

Binding of small effector molecule

Answer 9

ex. Promotes binding of DNA

Question 10

Protein-protein interactions

Answer 10

ex. Formation of dimers controls transcription

Question 11

Covalent modifications

Answer 11

ex. Attachment of a phosphate group to alter function

Question 12

Chromatin can be in 2 conformations

Answer 12

1. Closed conformation
2. Open conformation

Question 13

Closed Conformation (heterochromatin)

Answer 13

tightly packed conformation of chromatin that cannot be transcribed.

Question 14

Open Conformation
(euchromatin)

Answer 14

Loosely packed chromatin structure that is capable of being transcribed.

Question 15

Chromatin remodeling

Answer 15

change in chromatin structure that alters the composition of histones or the spacing of nucleosomes (or both).

Question 16

Chromatin remodeling is carried out by…

Answer 16

ATP-dependent chromatin remodeling complexes

Question 17

Eukaryotic gene regulation ________ __________ on these changes in chromatin structure

Answer 17

Depends partially

Question 18

Eukaryotic gene regulation affects the ability of transcription factors to

Answer 18

gain access and bind to their target sequences

Question 19

ATP-dependent chromatin-remodeling complexes change chromatin structure in 3 possible ways:

Answer 19

1. Change in nucleosome position
2. Histone eviction
3. Replacement with histone variants

Question 20

DNA Methylation

Answer 20

the phenomenon in which an enzyme covalently attaches a methyl group (-CH3) to a base (adenine or cytosine) in DNA

Question 21

DNA methyltransferase

Answer 21

the enzyme that attaches methyl groups to adenine of cytosine bases.

Question 22

DNA Methylation plays an important part in

Answer 22

1. genomic imprinting
2. X chromosome inactivation
3. Suppression of repetitive element transcription and transposition

Question 23

When DNA methylation is dysregualted it….

Answer 23

contributes to diseases like cancer

Question 24

DNA methylation usually inhibits the

Answer 24

initiation of transcription

Question 25

Most vertebrates and plants have

Answer 25

CpG islands

Question 26

CpG islands

Answer 26

a group of CG sequences that may be cluster near a promoter of a gene. The methylation of the cytosine bases usually inhibits transcription

Question 27

Housekeeping gene

Answer 27

a gene that encode a protein required in most cells of a multicellular organism

Question 28

The cytosine bases in the CpG islands of housekeeping genes are __________ so they are

Answer 28

unmethylated, always expressed in all cell types

Question 29

Tissue-specific gene

Answer 29

highly regulated and is expressed in a particular cell type

Question 30

DNA methylation plays an important role in suppressing tissue-specific genes in…

Answer 30

the wrong tissue type

Question 31

Methylation of CpG islands may enhance or prevent….

Answer 31

binding of regulatory transcription factors through silencing

Question 32

___ _________ is heritable

Answer 32

DNA methylation

Question 33

DNA will remain methylated through _____________ ___ _______ and production of ________ _____

Answer 33

subsequent DNA replication, daughter cells

Question 34

unmethylated DNA will remain __________ through subsequent DNA replication and production of daughter cells

Answer 34

unmethylated

Question 35

Modification example

Answer 35

Steroid hormones

Question 36

Ultimate action of a steroid hormone

Answer 36

to affect gene transcription

Question 37

in animals, steroid hormones act as _______ _________ that are synthesized by_________ _______ and secreted into the__________

Answer 37

signaling molecules, endocrine glands, bloodstream

Question 38

hormones are taken up by cells that respond to these substances in different ways

Answer 38

• may influence metabolism of nutrients
  *may influence development of secondary sexual characteristics and play a role in reproduction

Question 39

1st effect of glucocorticoid in mammals

Answer 39

1. hormone enters cytosol of cell through plasma membrane

Question 40

2nd effect of glucocorticoid in mammals

Answer 40

2. hormone binds to a glucocorticoid receptor

Question 41

3rd effect of glucocorticoid in mammals

Answer 41

3. receptor in a protein complex that releases HSP90 protein when the hormone binds to it

Question 42

4th effect of glucocorticoid in mammals

Answer 42

4. this exposes a nuclear localization site on the receptor that directs the receptor into the nucleus

Question 43

5th effect of glucocorticoid in mammals

Answer 43

two receptors come together to form a dimer and travel into the nucleus

Question 44

6th effect of glucocorticoid in mammals

Answer 44

dimer binds to a glucocorticoid response element (GRE)

Question 45

7th effect of glucocorticoid in mammals

Answer 45

Activates transcription of adjacent gene, leading to synthesis of encoding protein (involved in metabolism)