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biochem 2 > Transcription II > Flashcards

Transcription II Flashcards

1
Q

what is capping

A

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

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2
Q

function of cap

A

allows cell to distinguish mRNA from other types of RNA

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3
Q

spilceosomes

A

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

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4
Q

another name for spliceosome

A

snRNP

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5
Q

what 3 sites are important for splicing to occur

A

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

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6
Q

splicing reaction

A

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

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7
Q

functino of splicing

A

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

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8
Q

differential/alternate splicing

A

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

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9
Q

polyadenylation signal

A

3’ end of RNA specified by DNA signal

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10
Q

function of poly A tail

A

determinat of mRNA stability

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11
Q

is the poly A tail found elsewhere besides mRNA

A

no

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12
Q

where does mature mRNA need to go to be transalted

A

cytoplasm

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13
Q

what governs the stability of an mRNA molcule

A

its nucleotide sequence

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14
Q

how does degradation of mRNA start

A

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

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15
Q

what degrades the mRNA molecule from both ends

A

ribonucleases

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16
Q

how do you get beta-thalassemia

A

incorrect splicing

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17
Q

symptom of beta-thalassemia

A

profound anemia

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18
Q

mutation found in PKU patients

A

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

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19
Q

function of chromatin iremodeling complexes

A

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

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20
Q

how do HATs affect histones

A

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

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21
Q

affect of HDACs on histones

A

catalyze removal of acetyl groups from histone. inhibit transcription

22
Q

what happens when cytosine residues in DNA are methylated

A

produce 5’ methylcytosine

23
Q

where do proteins usually bind to DNA

A

major groove

24
Q

helix-turn-helix proteins

A

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

25
Q

characterisc of zinc finger protein

A

zinc required for protein folding and function,

alpha helix makes contact with the major groove of DNA

26
Q

example of zinc finger DNA binding protein

A

glucocorticoid receptor

27
Q

leucine zipper protein characteristic

A

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

28
Q

examples of leucine zipper protein

A

fos and jun

29
Q

LDL recptor

A

glycoprotein that spans plasma membrane

30
Q

waht does the LDL receptor gene recognize

A

apolipoprotein B and E

31
Q

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

A

endocytosis of receptor

uptake of LDL and VLDL into cell

32
Q

what is the relationship between LDL receptor gene and cholesteral

A

it’s icnreased in response to low cellular cholesterol

33
Q

what happens when you have increased transcription of LDL receptor gene

A

enchanges cholesterol uptake form blood

34
Q

what does the promotor of LDL receptor gene have

A

SRE-1

35
Q

function of SP-1

A

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

36
Q

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

A

CRSP

37
Q

what is SRE-1 bound to

A

SREBP-1a

38
Q

what is SREBP-1a

A

leucine zipper protein

39
Q

what happesn to LDL receptor gene when cholesterol levels fall

A

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

40
Q

what else does SREBP-1a do

A

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

41
Q

what is the major glucocorticoid secreted in humans

A

cortisol

42
Q

what happens when cortisol binds to glucocorticoid receptor

A

allows uptake of hormone/receptor complex into nucleus

43
Q

GRE

A

where hormone/receptor complex binds, an enchancer element

44
Q

in most tissues what do thyroid hormones do

A

stimulate metabolic rate

45
Q

where are receptors for thyroid hormone found

A

constituvtively in nucleus

46
Q

thyroid hormones receptors often bind to DNA as waht

A

heterodimers

47
Q

what is the other part of the thyroid hormone dimer

A

RXR

48
Q

complex of thyroid recpetor/RXR do what

A

recruit HDAC activity

49
Q

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

A

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

50
Q

symptom of rubinstein taybi syndrome

A

intellectual disability, abnormality

51
Q

what is rubinstein-taybi caused by

A

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

52
Q

tamoxifen

A

compeititve inhibitor of estrogen receptor, used for breast cancer treatment

biochem 2 (22 decks)

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