ch 19: control of gene expression in eukaryotes

Question 1

what are the gene expression controls in eukaryotes?

Answer 1

1. chromatin remodeling
2. transcription factors
3. splicing
4. mRNA stability
5. translation
6. post-translational modifications

Question 2

chromatin arrangement

Answer 2

chromatin contains a nucleosome that has 8 histones and DNA

Question 3

what is organization of chromatin determined by?

Answer 3

1. histone types in nucleosome
2. modifications to the tall regions of histones

Question 4

what are 2 main chromatin structures?

Answer 4

1. heterochromatin
2. euchromatin

Question 5

heterochromatin

Answer 5

• closed, tight-packed
• DNA hard to access by regulatory proteins
• genes not expressed

Question 6

euchromatin

Answer 6

-open, loosely packed
- DNA easy to access by regulatory proteins
- genes are expressed

Question 7

what partial charge do histones have?

Answer 7

partial positive

Question 8

what partial charge does DNA have?

Answer 8

negative

Question 9

what does adding an acetyl group to a histone tail do?

Answer 9

allows access to DNA for transcription

Question 10

what does adding an methyl group to a histone tail do?

Answer 10

stops translation by making the chromatin condensed

Question 11

what nucleotide base gets methylated?

Answer 11

cytosine

Question 12

what does chromatin arrangement determine?

Answer 12

which regions of DNA can be accessed by transcription factors and enzymes

Question 13

genes that are expressed on other chromosomes are ________

Answer 13

looped next to each other

Question 14

when is chromatin structure copied?

Answer 14

during S phase of the cell cycle

Question 15

what gets duplicated during chromosome duplication?

Answer 15

DNA and chromatin-associated proteins

Question 16

transcription factors

Answer 16

proteins: activators, repressors, and transcription factors (sequences)
DNA regions: enhancers, promoter, insulator, prometer-proximal, silencer

Question 17

core promoter

Answer 17

binding site for GTFs + where RNA polymerase II binds

Question 18

promoter proximal elements

Answer 18

binding site for activator/repressor proteins
- close to promoters

Question 19

distal regulatory regions

Answer 19

DNA sequences farther away from protein coding DNA sequence, can be upstream or downstream of coding region
- influences how much of a gene is expressed

Question 20

enhancer

Answer 20

increases txn

Question 21

silencer

Answer 21

decrease txn

Question 22

insulator

Answer 22

stops heterochromatin from spreading and silencing gene, maintains txn

Question 23

what do distal regulatory elements facilitate?

Answer 23

chromatin remodeling

Question 24

what do activators bind to?

Answer 24

enhancer regions and recruit HATs to decondense chromatin
- makes core promoter and promoter proximal elements exposed

Question 25

mediator protein

Answer 25

binds activating transcription factors to loop DNA and maintain open chromatin

Question 26

what does mediator proteins bind to after creating DNA loop?

Answer 26

GTFs which bind to RNA polymerase II to start transcription

Question 27

what can insulators do?

Answer 27

maintain open euchromatin loops - allows the gene to stay open

Question 28

what does the amount of transcription impact?

Answer 28

phenotype

Question 29

alternative splicing

Answer 29

controls which version of a protein is made

Question 30

mRNA stability and translation control

Answer 30

-micro RNAs degrade mRNA transcripts making gene expression changes more dynamic - micro RNAs can block translation by binding to mRNAs

Question 31

what do miRNAs bind to?

Answer 31

complementary sequence on mRNAs

Question 32

translational repression

Answer 32

only some miRNAs matched correctly to mRNA bases, which can reduce translation - it is reversible

Question 33

mRNA cleavage

Answer 33

all miRNAs complementary base pair with mRNA sequence, which results in cleavage of mRNA and translation does not occur - not reversible

Question 34

what do plants regulate?

Answer 34

global gene expression patterns in response to stress with miRNAs