Transcription II

Question 1

what is capping

Answer 1

complex of 3 enzymes form a complex with pol II and modfy the 5’ end of pre-mRNA into a cap

Question 2

function of cap

Answer 2

allows cell to distinguish mRNA from other types of RNA

Question 3

spilceosomes

Answer 3

recognize boundaries between exons and introns, catalyze cleavage adn rejioing of RNA molecule

Question 4

another name for spliceosome

Answer 4

snRNP

Question 5

what 3 sites are important for splicing to occur

Answer 5

5’ splice site
3’ splice site
branch point w/in intron

Question 6

splicing reaction

Answer 6

1) adenine residue attacks 5’ splice site, cutting the sufar-phosphate bakcbone
2) 5’ end covalently attachs to adenine nucleotide, making a loop
3) 3’ end reacts with 5’ end of next exon, joing together and releasing intron

Question 7

functino of splicing

Answer 7

allows more than 1 protein produce to be generated from a single pre-mRNA transcript

Question 8

differential/alternate splicing

Answer 8

pre-mRNA molecule can be spliced together generating different mRNA molcules

Question 9

polyadenylation signal

Answer 9

3’ end of RNA specified by DNA signal

Question 10

function of poly A tail

Answer 10

determinat of mRNA stability

Question 11

is the poly A tail found elsewhere besides mRNA

Answer 11

no

Question 12

where does mature mRNA need to go to be transalted

Answer 12

cytoplasm

Question 13

what governs the stability of an mRNA molcule

Answer 13

its nucleotide sequence

Question 14

how does degradation of mRNA start

Answer 14

shortening of poly A tail, triggers removal of 5’ cap

Question 15

what degrades the mRNA molecule from both ends

Answer 15

ribonucleases

Question 16

how do you get beta-thalassemia

Answer 16

incorrect splicing

Question 17

symptom of beta-thalassemia

Answer 17

profound anemia

Question 18

mutation found in PKU patients

Answer 18

single base change in 5’ splice donor site of one particular intron

Question 19

function of chromatin iremodeling complexes

Answer 19

protein machines tha tuse energy of ATP hydrolysis to change structure of nucleosomes temporailyt so DNA becomes less tightly bound to histone core

Question 20

how do HATs affect histones

Answer 20

reduce net positive change, decreases strength of their interaction with DNA

Question 21

affect of HDACs on histones

Answer 21

catalyze removal of acetyl groups from histone. inhibit transcription

Question 22

what happens when cytosine residues in DNA are methylated

Answer 22

produce 5’ methylcytosine

Question 23

where do proteins usually bind to DNA

Answer 23

major groove

Question 24

helix-turn-helix proteins

Answer 24

2 alpha helices conencted by a short chain of amino acids. side changes are important in DNA pbinding

Question 25

characterisc of zinc finger protein

Answer 25

zinc required for protein folding and function, | alpha helix makes contact with the major groove of DNA

Question 26

example of zinc finger DNA binding protein

Answer 26

glucocorticoid receptor

Question 27

leucine zipper protein characteristic

Answer 27

alpha-helix that has a leucine hydrophobic residue protruding down one side.

Question 28

examples of leucine zipper protein

Answer 28

fos and jun

Question 29

LDL recptor

Answer 29

glycoprotein that spans plasma membrane

Question 30

waht does the LDL receptor gene recognize

Answer 30

apolipoprotein B and E

Question 31

binding of apolipoprotein B or E with LDL receptor gene results in what

Answer 31

endocytosis of receptor | uptake of LDL and VLDL into cell

Question 32

what is the relationship between LDL receptor gene and cholesteral

Answer 32

it's icnreased in response to low cellular cholesterol

Question 33

what happens when you have increased transcription of LDL receptor gene

Answer 33

enchanges cholesterol uptake form blood

Question 34

what does the promotor of LDL receptor gene have

Answer 34

SRE-1

Question 35

function of SP-1

Answer 35

help with assemby of pol II and general transciription factors at TATA box

Question 36

what addition protein does SP-1 need in order to function

Answer 36

CRSP

Question 37

what is SRE-1 bound to

Answer 37

SREBP-1a

Question 38

what is SREBP-1a

Answer 38

leucine zipper protein

Question 39

what happesn to LDL receptor gene when cholesterol levels fall

Answer 39

entery of SREBP-1a into nucleus, where it binds to SRE-1, recruits HAT, relaxes chromaton allowing LDL transcription

Question 40

what else does SREBP-1a do

Answer 40

binds to promoter regions of genes involved with metabolism of both choelsterol and fatty acids

Question 41

what is the major glucocorticoid secreted in humans

Answer 41

cortisol

Question 42

what happens when cortisol binds to glucocorticoid receptor

Answer 42

allows uptake of hormone/receptor complex into nucleus

Question 43

GRE

Answer 43

where hormone/receptor complex binds, an enchancer element

Question 44

in most tissues what do thyroid hormones do

Answer 44

stimulate metabolic rate

Question 45

where are receptors for thyroid hormone found

Answer 45

constituvtively in nucleus

Question 46

thyroid hormones receptors often bind to DNA as waht

Answer 46

heterodimers

Question 47

what is the other part of the thyroid hormone dimer

Answer 47

RXR

Question 48

complex of thyroid recpetor/RXR do what

Answer 48

recruit HDAC activity

Question 49

what happens when thryoid hormones binds to thyroid receptor/RXR compelx

Answer 49

displacement of HDAC, binding of AHT complex, favors relaxation of chromatine sturucture which facilitates trasncrition

Question 50

symptom of rubinstein taybi syndrome

Answer 50

intellectual disability, abnormality

Question 51

what is rubinstein-taybi caused by

Answer 51

point mutations, small deletions and rearrangedment within genes encoding CBP or EP300

Question 52

tamoxifen

Answer 52

compeititve inhibitor of estrogen receptor, used for breast cancer treatment