lectures 7-9

Question 1

rap1 recruits:

Answer 1

Sir proteins

Question 2

Sir2 function

Answer 2

-histone deacetylase
-form heterochromatin
-move genes away from HML/HMR

Question 3

HML/HMR

Answer 3

constantly repressed genes in mating type loci of yeasts

Question 4

telomeres bind:

Answer 4

Rap1/SIR proteins

Question 5

permanent repression at telomeres mutation

Answer 5

lys -> arg

Question 6

permanent activation at telomeres mutation

Answer 6

lys -> glu

Question 7

acetylation causes:

Answer 7

-reduction of + charge
-open to euchromatin

Question 8

deacetylation causes:

Answer 8

-increase - charge
-form heterochromatin

Question 9

components of yeast loci repression

Answer 9

Rap1 - repressor
telomere - silencer
SIR3/4 - co-repressors
SIR2 - histone deacetylase

Question 10

yeast telomeres silencing steps

Answer 10

1. Rap1 binds nucleosome-free telomere
2. SIR3/4 bind Rap1, SIR2 bind SIR4
3. SIR2 deacetylases histone tails
4. more SIR3/4 bind deacetylated histone tails

Question 11

Ume6 repressor function

Answer 11

1. DNA-bind domain binds URS1
2. Sin3/Rpd3 deacetylase binds
3. nearby histone tails deacetylated, gene repressed

Question 12

Gcn4 activation steps

Answer 12

1. DNA-bind domain binds UAS
2. SAGA and Gcn5 histone acetyl-transferase binds
3. histone tails are acetylated and gene is transcribed

Question 13

chromatin remodelling complexes

Answer 13

-move nucleosomes along DNA to open promoters

Question 14

SW1/SNF ATPases

Answer 14

shift nucleosomes away from promoter allowing txn.

Question 15

mediator

Answer 15

-co-activator
-bind activators and GTF’s to enhance txn.

Question 16

epigenetics

Answer 16

inheritance of chromatin structure

Question 17

epigenetic marks

Answer 17

-methylation
-acetylation
-always rebuilt after replication fork

Question 18

DNA methylation

Answer 18

-always in heterochromatin
-H3 (K4) - activation
-H3 (K9) - repression

Question 19

histone acetylation

Answer 19

-always euchromatin
-H3 (K9) - always activation

Question 20

histone deacetylation

Answer 20

-always heterochromatin

Question 21

histone methylation

Answer 21

-either heterochromatin or euchromatin depending on modifications

Question 22

histone code

Answer 22

control of chromatin regions resulting from influences of post-translational modifications

Question 23

Me-DNA-bind-proteins

Answer 23

-recruit factors deacetylating histones and condensing chromatin

Question 24

mRNA components

Answer 24

-5’ cap
-introns removed by splicing
-poly A tail

Question 25

snRNA function

Answer 25

spliceosome

Question 26

siRNA function

Answer 26

-cleavage of target RNA, rapid degradation -bind perfectly

Question 27

miRNA function

Answer 27

-inhibit translation of target RNA, target for later degradation -bind imperfectly

Question 28

isoforms for neuron alternate splicing

Answer 28

576

Question 29

Ca2+ - activated K+ channel (neurons)

Answer 29

-7 a helices -cytosolic domain (opening of channel)

Question 30

drosophilia alternate splicing isoforms

Answer 30

95 exons, 38000 isoforms

Question 31

Sx1 function

Answer 31

-splicing suppressor / silencer -ONLY in females

Question 32

Tra function

Answer 32

-splicing activator -ONLY in females

Question 33

Dsx function

Answer 33

transcription activator OR repressor

Question 34

female Dsx protein

Answer 34

txn activator

Question 35

male Dsx protein

Answer 35

txn repressor

Question 36

Lin-4 / Let-7 function

Answer 36

-reduce translation of development in C.Elegans

Question 37

Drosha function

Answer 37

-endoribonuclease -cleave pre-miRNA

Question 38

Pasha function

Answer 38

-bind double stranded pri-miRNA

Question 39

Exportin5 function

Answer 39

-transport processed miRNA to cytoplasm

Question 40

DICER function

Answer 40

-fragment double stranded RNA

Question 41

Argonaut function

Answer 41

-RNA helicase -moves target strand to RISC

Question 42

RNA interference steps

Answer 42

1. dsRNA fragmented by DICER 2. dsRNA binds RISC to form inactive complex 3. Argonaut unwinds dsRNA, activates RISC 4. RISC cleaves target mRNA guided by sssiRNA

Question 43

PAX6 components/function

Answer 43

-3 promoters -txn. activator

Question 44

Pax6 10.5 days post-fertilization

Answer 44

-enhancosomes -txn. initiated at pancreas and lens plate promoters

Question 45

Pax6 13.5 days post-fertilization

Answer 45

-lens enhancer stops, pancreatic continues -retina starts