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Biochemistry > Transcription > Flashcards

Flashcards in Transcription Deck (52):
1

what is the one gene one enzyme hypothesis

a single gene codes for one enzyme

2

DNa dependent synthesis of RNA or the use of DNA as a template to synthesize RNA

transcription

3

percent of genes in prokaryotes

3-30%

4

percent of genes in eukaryotes

1-10%

5

a sequence of 20-200 bases "upstream" from a gene that serves as a recognition site for binding RNA polymerase

promoter

6

promoter contains these regions that identify the region as a promoter

consensus sequeces

7

where are the consensus sequences located

-35 and -10 nucleotides from the promoter

8

the promoter occurs on the ____ strand

nontemplate

9

the enzyme that "reads" DNA to synthesize RNA

RNA polymerase

10

core enzyme of RNA polymerase

two alphas
beta
beta prime
omega

11

subunit for DNA binding

beta prime

12

subunit for the catalytic site

beta

13

subunit that deals with promoter binding, assembly and regulation

alpha

14

subunit that deals with structural role, restores activity

omega

15

promoter recognition that transiently bind to core enzyme to allow binding to correct strand and initiation site

sigma factor

16

three stages of transcription

initiation
elongation
termination

17

RNA polymerase binds to promoter causing _____ and _____

strand separation and unwinding

18

Initiation is complete after

about 10 NTPs have been added

19

what continues as the sigma factor falls away

elongation

20

An ATP dependent helicase that catalyzes the unwinding of RNA:DNA duplex hybrids during transcription to promote termination of prokaryotic transcription

Rho factor

21

terminator makes this structure in prokaryotes

hairpin structures

22

five points about eukaryotic transcription

1. three different RNA polymerase that cannot initiate transcription
2. promoters are more complex that consensus sequences
3. initiation requires many transcription factors to activate RNA polymerase
4. regulatory elements modify gene expression
5. transcripts require considerable processing prior to translation

23

location and function of RNA polymerase I in eukaryotes

located in nucleolus
transcribes large rRNAs

24

location and function of RNA polymerase II in eukaryotes

located in nucleus
transcribes mRNAs and snRNAs

25

location and function of RNA polymerase III in eukaryotes

located in the nucleus
transcribes tRNAs and 5s rRNAs

26

position and description of TATA box

-25
indicates transcription start site

27

position and description of CAAT box

-50
indicates "strong" promoter (makes a lot of mRNA)

28

location and description of GC box

-80
indicates "housekeeping" genes

29

code for proteins needed all the time

housekeeping genes

30

eukaryotic initiation involves

several transcription factors

31

transcription factors sequentially bind to

TATA region and polymerase

32

polymerase complex binds to

promoter

33

activates polymerase via phosphorylation and transcription begins

TFIIH

34

a short segment of DNA near eukaryotic promoters that bind transcription of certain genes

enhancers

35

what allows for the interaction with RNA polymerase

formation of DNA loop

36

do mRNA's require processing in prokaryotes

no

37

three main types of mRNA processing in eukaryotes

5' capping
3' polyadenylation
splicing

38

addition of 7-methyl guanosine to the 5' end

5' capping

39

the addition of 100-250 adenylate residues to the 3' end

3' polyadenylation

40

the removal of introns and ligation of exons

splicing

41

two characteristics of 5' cap

1. methylguanosine linked via 5' to 5' triphosphate
2. 2' OH's of up to 3 neucleotides are methylated

42

5' cap serves as a

recognition site for ribosome attachment and prevents transcript degradation by exonucleases

43

what is the termination sequence of eukaryotic RNAs

AAUAAA

44

two big functions of the poly A tail

help direct mRNA's out of the nucleus
protects 3' end from exonuclease degradation

45

what does the length of the poly A tail say about the RNA

describes its longevity

46

pre-mRNAs have short nucleotide sequences at the end of introns that serve as

splicing signals

47

recognize consensus splice sites via RNA base pairing

snRNPs

48

what makes a spliceosome

several snRNPs join together

49

job of spliceosomes

cut out and attaches exon ends together

50

where does RNA splicing occur

in in the nucleus

51

introns may provide

cross over recombination sites

52

facilitate recombination within proteins to allow novel protein function

exon shuffling