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genetics > chapter 8 part 1 > Flashcards

chapter 8 part 1 Flashcards

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Biology 101 flashcards
1
Q

RNA ribonucleotide composition

A
  • ribose sugar
  • nucleotide base
  • 1+ phosphate groups
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2
Q

how is RNA different from dNA

A
  1. uses uracil instead of thymine
  2. has sugar ribose instead of deoxyribose
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3
Q

difference between ribose and deoxyribose

A

2’ C of ribose has OH group instead of H in DNA

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4
Q

RNA polymerase function

A

catalyzes addition of each ribonucleotide to 3’ end of nascent (growing) strand and forms phosphodiester bonds between nucleotides

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5
Q

how many types of RNA pol catalyzes transcription of all RNAs in E. coli (prokaryotes)

A

one single type

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6
Q

Rifampicin

A

inhibits RNA synthesis in prokaryotes by inhibiting formation of first phosphodiester bond

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7
Q

what happens when sensitive bacterial strains are exposed to rifampicin

A

unable to synthesize mRNA, tRNA, or rRNA and die

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8
Q

mRNA

A

short-lived intermediary between DNA and protein

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9
Q

what is mRNA produced by

A

protein-encoding genes

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10
Q

what is the only type of RNA that undergoes translation

A

mRNA

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11
Q

what is transcription of mRNA often followed by

A

post-transcriptional processing

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12
Q

functional RNAs

A

don’t encode proteins, but instead perform functional/structural roles in cell

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13
Q

transfer (tRNA)

A

responsible for binding an amino acid and depositing it for inclusion into growing protein chain

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14
Q

ribosomal (rRNA)

A

combines with numerous proteins to form ribosomes

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15
Q

small nuclear (snRNA)

A

various types found in nucleus of eurkaryotes
- plays role in mRNA processing

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16
Q

micro (miRNA)

A

active in plant and animal cells
- involved in post-transcriptional regulation of mRNA

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17
Q

small interfering (siRNA)

A

protects plant and animal cells from production of viruses and movement of transposons

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18
Q

ribozymes

A

certain RNAs in eukaryotic cells that have catalytic activity

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19
Q

transcription

A

synthesis of a single-stranded RNA molecule by RNA polymerase

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20
Q

template strand

A

non-coding strand/antisense strand, read to assemble complementary, antiparallel strand of ribonucleotides

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21
Q

coding strand

A

non-template strand/sense strand, complementary to template strand

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22
Q

4 stages of transcription in bacteria

A
  1. promoter recognition
  2. transcription elongation
  3. chain elongation
  4. chain termination
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23
Q

where is the promoter usually found

A

immediately upstream (5’) to start of transcription

24
Q

what is the promoter also referred to as

A

+1 nucleotide

25
Q

where does the RNA polymerase bind

A

the promoter
- consensus sequences within this region

26
Q

3 parts of gene

A
  1. promoter
  2. coding region
  3. termination region
27
Q

coding region

A

portion of gene that contains the information needed to synthesize the protein product

28
Q

termination region

A

regulates cessation of transcription

29
Q

where is the termination region

A

immediately downstream (3’) to coding segment

30
Q

composition of bacterial RNA polymerase holoenzyme

A
  • pentameric core enzyme that binds to:
  • sigma subunit
31
Q

composition of large core enzyme in RNA pol holoenzyme

A

aI, aII, b, b and one w subunit

32
Q

abilities of core enzyme in RNA pol

A
  • transcribe RNA from DNA template
  • can’t bind promoter or initiate RNA synthesis without sigma subnit
33
Q

alternative sigma subunits

A

different types of sigma subunits that alter core enzyme conformation in dif ways to facilitate association with different types of promoters

34
Q

prokaryotic promoter sequences

A
  • single-stranded shorthand form
  • 5’ to 3’ on coding strand
  • Pribnow box (-10 consensus sequence)
  • 6 bp region (-35 consensus sequence)
35
Q

Pribnow box -10 consensus sequence

A

5’=TATAAT-3’

36
Q

-35 consensus sequence

A

5’-TTGACA-3’

37
Q

where specifically does RNA polymerase bind in bacteria

A

-10 and -35 consensus sequences, and occupies space between and around them

38
Q

transcription initiation 2 initial steps

A
  1. holoenzyme makes loose attachment to promoter sequence to form the closed promoter complex
  2. holoenzyme next unwinds about 18 bp of DNA around the -10 position to form the open promoter complex
39
Q

what do alternative sigma units allow for

A

holoenzyme binding to variant promoters

40
Q

transcription elongation

A
  • holoenzyme initiated RNA synthesis at +1 site
  • sigma subunits dissociate after first 8-10 nucleotides
  • DNA unwound ahead of enzyme to maintain transcription bubble of about 18 nucleotides
41
Q

transcription termination

A
  • 3’ end of RNA trails off core enzyme
  • core enzyme dissociates from DNA
  • second round may begin
42
Q

what do DNA termination sequences usually contain

A

repeating sequence

43
Q

2 types of termination

A
  1. intrinsic
  2. rho-dependent
44
Q

intrinsic termination

A

presence of repeated sequences induces secondary structures in newly formed RNA that induce termination
- inverted repeat followed by string of A
- mRNA contains stem-loop structure (hairpin)
- hairpin followed by Us, causes RNA pol to slow down and destabilize
- pol releases transcript and separate from DNA

45
Q

rho-dependent termination

A
  • requires dif termination sequence and rho protein (small GTPase)
  • rho induces termination
  • no string of uracils
  • rho utilization (rut) site - 50 nuc. of C
  • rho activated by ATP, binds to rut site
  • rho moves along transcript to rNA pol and catalyzes released of mRNA from RNA pol, triggers release of pol from DNA
46
Q

rho protein components

A

6 identical polypeptides with 2 functional domains each

47
Q

what family is rho a member of

A

ATP-dependent hexametric helices

48
Q

do eukaryotic genes require processing to remove exons or introns?

A

introns

49
Q

what is eukaryotic DNA associated with to form chromatin

A

proteins

50
Q

what does the chromatin composition affect?

A

its transcription

51
Q

RNA polymerase I

A

transcribes 3 rRNA genes

52
Q

RNA polymerase II

A

transcribes protein-coding genes (mRNA) and most snRNA genes

53
Q

RNA polymerase III

A

transcribes tRNA, one snRNA, and on rRNA

54
Q

how many units of eukaryotic and archaeal RNA pol share homology with bacterial polymerase

A

5 subunits

55
Q

how many additional subunits do archaea and eukaryotes have?

A

6-11

genetics (37 decks)

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