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Molecular BIO > 7-8: Transcription and Translation > Flashcards

7-8: Transcription and Translation Flashcards

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1
Q

What is the function of mRNA?

A

messenger RNA that codes fro proteins

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2
Q

What is rRNA?

A

ribosomal RNA, that forms the basic structure of the ribosome and catalyze protein synthesis

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3
Q

What is tRNA?

A
  • transfer RNA

- acts as an adaptor between mRNA and amino acidss

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4
Q

What is snRNA?

A
  • small nuclear RNA

- splice pre-RNA and other nuclear function

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5
Q

What is snoRNA?

A
  • small nucleolar RNA

- process and chemically modify rRNAs

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6
Q

What are miRNA?

A
  • microRNA

- regulate gene expression by blocking translationof specific mRNA and produce their degradation

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7
Q

What are siRNA?

A
  • small interfering RNA

- control gene expression by directing degradation of selective mRNA and establishing compact chromatin structures

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8
Q

Why can RNA poly have a lower fidelity than that of DNA poly?

A

-the mistakes that are made are not transmitted to the progeny, therefore mistakes are more allowed

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9
Q

What subunits make up the bacterial RNA polym?

A
  • alpha2, beta, beta prime, sigma
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10
Q

The mRNA strand that is synthesized is most similar to what?

A
  • complementary to the template strand

- identical to the coding strand

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11
Q

What are two common motifs in bacteria that signal for transcription initiation?

A
  • TTGACA at -35

- TATAAT box at -10 from the initiation site

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12
Q

What does RNA polym encounter that helps initiate the termination of transcription?

A
  • GC,AT rich region contributes to the formation of a hairpin which causes a pause in RNA Polym.
  • the hairpin adds new tension to the RNA polym and RNA strand, causing it to destabilize due to weak attachment bc of increased AU interactions
  • mRNA leaves and the transcription bubble closes
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13
Q

Eukaryotes require more than one RNA polymerase to perform transcription. What are these and which is the most important?

A
  1. RNA Polymerase I, II, III

2. polym II: all protein coding genes, and the other RNA types mentioned

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14
Q

What is the main regulator that controls the RNA poly II activity?

A
  • the regulator is phosphorylation of Ser residues located on the carboxyl-terminal domain
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15
Q

What unit contains the TBP, TATA-box binding protein?

A
  1. TFII D recognizes the TATA binding region
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16
Q

What factors combine to form the transcription initiation complex?

A

TFIIB, TFIIF, RNA poly II, TFIIE, and TFIIH

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17
Q

What process occurs that causes the end of initiation and begins the elongation process?

A
  • TFIIH phosphorylates the carboxyl-terminal domain, and forces the polymerase to leave the promoter
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18
Q

Eukaryotic polymerase TFIID TBP subunit does what function?

A
  • recognize the TATA box
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19
Q

Eukaryotic polymerase TFIID TAF subunit has what function?

A
  • regulate DNA binding by TBP, and recognize other DNA sequence near transcription start point
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20
Q

Eukaryotic polymerase TFIIB has what function?

A
  • recognize BRE element in promoters. accurately positions RNA polymerase at the start site of transcription
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21
Q

Eukaryotic polymerase TFIIF has what function?

A
  • stabilize RNA polym interaction with TBP and TFIIB
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22
Q

Eukaryotic polymerase TFIIE has what function?

A
  • attract and regulate TFIIH
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23
Q

Eukaryotic polymerase TFIIH has what function?

A
  • unwinds DNA at start point, releases RNA polymerase from the promoter
24
Q

What are recruited to increase the accessibility of DNA to specific enzymes?

A
  1. chromatin modifying enzymes
    - chromatin remodeling complex
    - histone modifying enzymes
25
Q

What RNA processing occurs before the mRNA is released from the nucleus into the cytoplasm in eukaryotes?

A
  1. RNA capping to the 5’ end
  2. RNA splicing, which removes non-coding sequences
  3. Poly A tail to the 3’ end
26
Q

What is the 5’ cap formed by?

A

7-methylguanosine that is bound to the 5’end via a triphosphate bridge

27
Q

What are the functions of the 5’ cap that is added to mRNA before it leaves the nucleus?

A
  1. marks the translation start site
  2. protects mRNA from phosphatases and nucleases
  3. binds to a cap binding complex to facilitate RNA processing and export.
28
Q

What two proteins are attached to the newly formed RNA as it is formed?

A
  1. cleavage stimulation factor (CstF)

2. Cleavage and polyadenylation specificity factor (CPSF)

29
Q

Where does the cleavage stimulation factor (CstF) bind to the new RNA strand?

A

to the GU rich region

30
Q

Where does cleavage and polyadenylation factor bind on the new RNA strand? (CPSF)

A

binds at the AAUAAA 3’ end

31
Q

What are the general process that take place to get eukaryotes DNA to protein?

A
  1. transcription in nucleus to form primary RNA transcript
  2. RNA modification (poly A tail, 5’ cap, splicing)
  3. nuclear exportation
  4. translation in cytoplasm to form proteins
32
Q

What are the general process that take place to get prokaryotes DNA to protein?

A
  1. transcription occurs in the cytoplasm

2. mRNA is directly translated into protein

33
Q

What is the function of a mediator?

A

allows the activator proteins to communicate with RNA Pol II and general transcription factors

34
Q

What is the primary reason chromatin modifying enzymes are used for?

A

allow more access to chromatin remodling complex

and histone modifying enzymes

35
Q

Where does translation occur?

A

on ribosomes

36
Q

What is the function of tRNA?

A
  1. adaptor that binds to specific codons and brings an amino acid to incorporate into the polypeptide chain
37
Q

What are two important regions on the tRNA?

A
  1. anticodon sequence

2. acceptor stem

38
Q

What is the anticodon region on tRNA used for?

A

Allows for complementary binding on an mRNA molecule

39
Q

What is the acceptor stem of tRNA used for?

A

This is a CCA region that binds to the amino acids, that corresponds with the proper anticodon sequence

40
Q

What is the best explanation as to why a large majority of codons for a single amino acid differ in the 3rd binding region?

A

wobble hypothesis

41
Q

How are amino acids attached to the correct tRNA?

A

use of aminoacyl-tRNA synthetases; which use covalent bonds to bind the AA to the 3’terminal ribose residue

42
Q

How does hydrolytic editing work, and what is it for?

A
  1. an editing region that uses the size of the attached amino acid to verify it correct. if not it is cleaved and removed.
43
Q

What are the prokaryote and eukaryote ribosomes?

A
  1. prokaryote: 70S

2. eukaryote: 80S

44
Q

What is thr primary function of the small s.u.?

A

form a framework where tRNA can accurately match with there codon

45
Q

What is the large s.u. function?

A

catalyze the formation of peptide bond linking the AA together on the polypeptide chain

46
Q

What are the 4 steps of translation?

A
  1. tRNA binds
  2. peptide bond forms
  3. large subunit translocates
  4. small subunit translocates
47
Q

How does the small subunit bind to the mRNA?

A

recognize the 5’cap and the eIF4E and eIF4G

48
Q

Which elongation factors aid eukaryotes to improve the efficiency of operation?

A

EF1 and EF2

49
Q

Which elongation factors aid bacteria with elongation?

A

EF-Tu and EF-G

50
Q

What is a way that antibiotics are effective against bacterial infections?

A

they bind to ribosomes and interfere with protein synthesis

51
Q

What effect does tetracycline have on bacteria?

A

blocks aminoacyl-tRNA binding to the A site

52
Q

What does streptomycin do to bacteria?

A

prevents the transition from translation initiation to elongation.
introduces miscoding

53
Q

What makes erythromycin an effective antibiotic against bacterial microbes?

A

binds in the exit channel of the ribosome and inhibits elongation of the peptide chain

54
Q

Why is puromycin effective against bacteria and eukaryotes?

A

releases the nascent peptide by adding to the growing chain end

55
Q

Why is cycloheximide effective against eukaryotes by not bacteria?

A

blocks translocation on ribosomes

Molecular BIO (24 decks)

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