2.13 Transcription Flashcards Preview

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Flashcards in 2.13 Transcription Deck (76)
1

Process of synthesizing RNA from a DNA template

Transcription

2

Transcription is the first step of ___

Gene expression

3

Runs from 3' -> 5' direction

Template/antisense/non-coding strand

4

Synthesized RNA appears similar to the ____ strand, which runs from 5'-> 3' direction

Non-template/sense/coidng strand

5

Corresponds to the first nucleotide expressend in the 5' end of the synthesized RNA

+1

6

Serves as the apoenzyme
Protein component of the RNA polymerase

Core enzyme

7

Core enzyme is composed of 5 units: __

alpha-alpha-beta-beta'-omega

8

Assembly of subunits

alpha (1)

9

Promoter-binding site
Recognizes the promoter region

alpha (2)

10

Nucleotide binding site

beta

11

Catalytic site
Possesses inherent DNA-DNA helicase activity in the breakage of hydrogen bonds
Also binds incoming NTPs to the growing mRNA strand via phosphodiester bonds

beta'

12

Stabilizes RNA molecule

omega

13

The only responsible for RNA elongation

5'->3' RNA polymerase

14

Non-protein component that activates the core enzyme

Coenzymes

15

Increase RNA polymerase affinity for promoter region
Unique for each RNA synthesized

Sigma factor

16

Signal end of transcription only for rho-dependent termination

Termination factors

17

Termination factors are also called the ___

rho factor

18

3 processes of prokaryotic transcription

Initiation
Elongation
Termination

19

Occurs at the promoter region

Initiation

20

Usually located -8 to -10 bases to the left of +1 (downstream)

Pribnow Box

21

Base sequence of Pribnow box

5'-TATAAT-3'

22

Usually located -35 bases to the left of +1 (downstream)

-35 sequence

23

Base sequence of -35 sequence

5'-TTGACA-3'

24

Sigma factor is released
Takes place through the RNA polymerase

Elongation

25

Recognizes the C-rich regions near the 3' end

rho-dependent termination

26

rho factors has the ____, to separate the template DNA stand and the synthesized RNA strand at the end of transcription

RNA-DNA helicase activity

27

RNA forms a hairpin turn via palindromic sequences

rho-independent temination

28

Bonds have high melting point and as strong and stable

G-C rich regions

29

Facilitates the separation of newly synthesized RNA strand

U-A rich regions

30

Binds to and changes the morphology of beta subunits of bacterial RNA polymerase
Blocks or suppresses the initiation step

Rifampin

31

Binds to the DNA-RNA complex which results to a barricade on the template strand
Prevents further elongation of strand

Dactinomycin

32

Basically, eukaryotic transcription follows the same processes as prokaryotic transcription; however, eukaryotic transcription:

1. Affected by chromatin structure
2. Affected by DNA methylation
3. Affected by histone acetylation
4. HasTATA box and CAAT box as promoter regions
5. Has TFIID as transcription factors

33

Relaxed form, actively transcribed

Euchromatin

34

Condensed form
Tightly packed
Inactive segments, transcriptionally silenced

Heterochromatin

35

Interconversion of the two forms (euchromatin and heterochromatin)

Chromatin remodeling

36

Chromatin remodeling involves acetylation of lysine residues at amino terminus of histones, which is mediated by

Histone acetyltranserases

37

Chromatin remodeling also involves removal of acetyl group in lysine residues, mediated by __

Histone deacetylases

38

Presence of methyl groups in DNA (enhances/inhibits) eukaryotic transcription

Inhibits
Methyl groups can physically prevent binding of transcriptional proteins

39

Presence of acetyl groups in the DNA (enhances/inhibits) eukaryotic transcription

Enhances
Presence of acetyl groups reduces interaction between histone tails and nucleosomes, making it relazed and transcriptionally active

40

Another term for TATA box

Goldberg-Hogness Box

41

Base sequence of TATA box

5'-ATATAAAA-3'

42

Location of TATA box

-25 region

43

Base sequence of CAAT box

5'-GGCCAATCT-3'

44

Location of CAAT box

-70 region

45

Eukaryotic promoter regions

TATA box
CAAT box

46

Binds to TATA box
Similar to alpha subunit in prokaryotes

TFIID

47

Eukaryotic transcription factors

TFIID

48

Type of eukaryotic RNA polymerase in nucleolus

RNA polymerase I

49

Product
RNA polymerase I

Large rRNA

50

Type of eukaryotic RNA polymerase that uses different promoter regions and affected by enhancers and silencers

RNA polymerase II

51

RNA polymerase II is inhibited by ___

Amanita phalloides

52

Product
RNA polymerase II

mRNA
snRNA

53

Product
RNA polymerase III

tRNA
5S rRNA
snRNA

54

Type of eukaryotic RNA polymerase that resembles prokaryotic RNA polymerase

Mitochondrial polymerase

55

Reasons for modification of eukaryotic RNA

Complexity of RNA
Cell compartment issues
Transcription-export

56

Introns are removed from anticodon loop via ____

tRNA splicing endonuclease

57

Intervening sequences

Introns

58

Expressed sequences

Exons

59

5' and 3' are trimmed

tRNA modifications

60

Addition of certain sequences at 3' end and modification to unusual bases

tRNA modifications

61

4 mRNA modifications

5' capping
3' Poly-A Tail
Removal of introns
Alternative splicing

62

Used for translation initiation and stabilizes mRNA

5' capping

63

5' capping is facilitated by ___

guanylyltransferase
guanine-7-methyltransferase

64

In 5' capping, the cap is ___

7-methylguanosine triphosphate

65

Addition of 40-200 adenine bases

3' Poly-A tail

66

Facilitates 3' Poly-A Tail

Polyadenylate polymerase

67

3' poly-A tail is used for protection against ___

Exonuclease

68

Facilitates exit of mRNA from nucleus

3' Poly-A tail

69

Facilitated in a spliceosome

Removal of introns

70

Removal of introns forms a ___-- bonds will form on the loop and spliceosome will cut loop leaving RNA

Lariat loop

71

snRNA + other protein

snRNP

72

mRNA + snRNP

spliceosome

73

Forms antibodies that attack snRNPs

SLE
Systemic lupus erythematosus

74

Due to aberrant beta-globin mRNA splicing a lot of introns that aren't removed properly

beta thalassemia

75

Combination of different exons from pre-mRNA will yield different combinations of mRNAs and different proteins

Alternative splicing

76

Testament to efficiency of eukaryotic mRNA in creating more proteins

Alternative splicing