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chapter 8 Flashcards

1
Q

what do rna ribonucleotides contain

A

ribose sugar, a nucleotide base, one or more phosphate groups

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2
Q

what are the two differences from DNA with RNA?

A

uracil instead of thymine
- the sugar ribose is used rather than deoxyribose

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3
Q

what is RNA polymerase?

A

it catalyzes the addition of each robinucleotide to the 3’ end of the growing strand
forms phosphodiester bonds between the nucelotides

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4
Q

a single type of rna catalyzes the transcription of all ______ in _________

A

RNA; e.coli

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5
Q

rifampicin

A

inhibits RNA synthesis (in prokaryotes) by inhibiting formation of the phosphodiester bond

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6
Q

what is mRNA

A

-produced by protein-encoding genes
-short-lived middle man between DNA and protein

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7
Q

what is the only type RNA that undergoes translation?

A

mRNA

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8
Q

what is the transcription of mRNA often followed by?

A

post-transcriptional processing

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9
Q

what do functional RNA’s do?

A

they perform functional/structural tasks, THEY DO NOT ENCODE PROTEINS

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10
Q

tRNA

A

-encoded in dozens of forms
-is responsible for binding an amino acid and dispositing it for inclusion into a growing protein chain

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11
Q

rRNA

A

combines with numerous proteins to form ribosomes

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12
Q

snRNA (small nuclear)

A

found in the nucleus of eukaryotes and play a roll in mRNA processing

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13
Q

miRNA (micro)

A

in plant and animal cells
involved in post-transcription regulation of mRNA

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14
Q

siRNA (small interfering RNA)

A

protects plant and animal cells from viruses and movement of transposons

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15
Q

ribozymes

A

certain RNAs in eukaryotic cells that have catalytic activity

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16
Q

what are the four stages of transcription in bacteria?

A
  1. promoter recognition
  2. transcription initiation
  3. chain elongation
  4. chain termination
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17
Q

what is transcription

A

the synthesis of a single-stranded RNA molecule by RNA polymerase

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18
Q

template strand (non-coding strand)

A

what the polymerase reads of the DNA to make a complementary, anitparallel strand of ribonucleoties

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19
Q

coding strand (non-template strand)

A

complementary to the template strand

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20
Q

where is the promoter at the start of transcription?

A

immediately upstream (5’)

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21
Q

what is the promoter referred to as?

A

the +1 nucleotide

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22
Q

what is the promoters role?

A

it is the actual binding site for RNA polymerase

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23
Q

what is the coding region of the gene?

A

portion that contains information needed to synthesize the protein product

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24
Q

what is the termination region of the gene?

A

it regulates cessation of transcription

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25
where is the termination region located?
immediately downstream (3') to the coding segment of the gene
26
what is the bacterial RNA polymerase holoenzyme composed of?
a pentameric core enzyme that binds a sixth subunit- the sigma subunit
27
what is the large core enzyme composed of?
sigma1, sigma2, beta, beta', and one omega subunit
28
what can't the core enzyme do without a sigma subunit?
it cannot bind the promoter or initiate RNA synthesis
29
what are the other types of sigma subunits called?
alternative sigma subunits
30
what do alternative sigma subunits do?
alter core enzyme conformation in slightly different ways to facilitate association with different types of promoters
31
what is a promoter?
a double stranded DNA sequence that the RNA polymerase binding site
32
where is the promoter located for bacterial (prokaryotic) things
a short distance upstream of the coding sequence. within a few nucleotides of +1
33
where does the RNA polymerase bind to the consensus sequence?
within the region of the promoter
34
what is the prinbow box or -10 consensus sequence?
a six base pair region in the promoter at the negative 10 nucleotide 5'-TATAAT-3'
35
what is the -35 consensus sequence?
5'-TTGACA-3'
36
what does RNA Polymerase bind to in a prokaryotic promoter sequence?
-10 and -35 sequences and occupies the space between and around them
37
Transcription Initiation
1. holoenxyme makes loose attachment to the promoter sequence to form the closed promoter complex 2. holoenzyme unwinds about 18bp of DNA around the -10 position to form the open promoter complex 3. holoenzyme progresses downstremm to initiate RNA synthesis at the +1 site
38
what does alternative sigma subunits allow for?
holoenzyme binding to variant promoters
39
how long is the transcrption bubble in trancription elongation?
18 nucleotides
40
when do the sigma subunits dissociate?
after the first 8 to 10 RNA nucleotides are polymerized
41
what happens to the core enzyme after trascription is completed?
the 3' end of the RNA trails off the core enzyme and becomes dissociates from the DNA
41
what is a dna termination sequence
a repeating sequence that teriminates the transcription in bacteria
42
intrinsic termination
the repeated sequence induces secondary structures in the newly formed RNA that induce termination
43
rho-dependent termination
uses a different termination sequence and the rho protein (small GTPase)
44
what is the rho enzyme do?
an additional enzyme that helps induce termination
45
how does most bacteria termination occur?
via intrinisc termination
46
what is a hairpin
a short stem-loop structure
47
what is intrisic termination
where termination sequences include an inverted repear followed by a string of adenines
48
what is the hairpin followed by?
a series of Us in the mRNA that causes the RNA polymerase to slow down and destabalize
49
what induces the polymerase to release the transcript and seperate from DNA?
the instability caused by the slowing polymerase and the U-A base pairs
50
rho-dependent termination does not have a string of ______
uracils
51
what does rho-dependent termination instead of uracils?
rho utilization site (rut site) a stretch of about 50 nucleotides rich in cytosine
51
how are rho proteins activated?
by ATP binding to one of the functional domains, faciliating binding to the rut site
52
rna polymerase I
transcribes three ribosomal RNA genes
52
how many polypeptides do rho proteins contain?
6 identical polypeptides with two functional domains each
52
rna polymerase II
transcribes protein coding genes (mRNA) and most small nuclear genes
53
rna pol III
transribes tRNA, one small nuclear RNA, and one ribosomal RNA
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genetics (37 decks)

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