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genetics > chapter 8 part 1 > Flashcards

chapter 8 part 1 Flashcards

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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

Study These Flashcards
A

immediately upstream (5’) to start of transcription

24
Q

what is the promoter also referred to as

Study These Flashcards
A

+1 nucleotide

25
where does the RNA polymerase bind
the promoter - consensus sequences within this region
26
3 parts of gene
1. promoter 2. coding region 3. termination region
27
coding region
portion of gene that contains the information needed to synthesize the protein product
28
termination region
regulates cessation of transcription
29
where is the termination region
immediately downstream (3') to coding segment
30
composition of bacterial RNA polymerase holoenzyme
- pentameric core enzyme that binds to: - sigma subunit
31
composition of large core enzyme in RNA pol holoenzyme
aI, aII, b, b and one w subunit
32
abilities of core enzyme in RNA pol
- transcribe RNA from DNA template - can't bind promoter or initiate RNA synthesis without sigma subnit
33
alternative sigma subunits
different types of sigma subunits that alter core enzyme conformation in dif ways to facilitate association with different types of promoters
34
prokaryotic promoter sequences
- single-stranded shorthand form - 5' to 3' on coding strand - Pribnow box (-10 consensus sequence) - 6 bp region (-35 consensus sequence)
35
Pribnow box -10 consensus sequence
5'=TATAAT-3'
36
-35 consensus sequence
5'-TTGACA-3'
37
where specifically does RNA polymerase bind in bacteria
-10 and -35 consensus sequences, and occupies space between and around them
38
transcription initiation 2 initial steps
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
what do alternative sigma units allow for
holoenzyme binding to variant promoters
40
transcription elongation
- 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
transcription termination
- 3' end of RNA trails off core enzyme - core enzyme dissociates from DNA - second round may begin
42
what do DNA termination sequences usually contain
repeating sequence
43
2 types of termination
1. intrinsic 2. rho-dependent
44
intrinsic termination
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
rho-dependent termination
- 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
rho protein components
6 identical polypeptides with 2 functional domains each
47
what family is rho a member of
ATP-dependent hexametric helices
48
do eukaryotic genes require processing to remove exons or introns?
introns
49
what is eukaryotic DNA associated with to form chromatin
proteins
50
what does the chromatin composition affect?
its transcription
51
RNA polymerase I
transcribes 3 rRNA genes
52
RNA polymerase II
transcribes protein-coding genes (mRNA) and most snRNA genes
53
RNA polymerase III
transcribes tRNA, one snRNA, and on rRNA
54
how many units of eukaryotic and archaeal RNA pol share homology with bacterial polymerase
5 subunits
55
how many additional subunits do archaea and eukaryotes have?
6-11

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