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chapter 8 Flashcards

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Biology 101 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
Q

where is the termination region located?

A

immediately downstream (3’) to the coding segment of the gene

26
Q

what is the bacterial RNA polymerase holoenzyme composed of?

A

a pentameric core enzyme that binds a sixth subunit- the sigma subunit

27
Q

what is the large core enzyme composed of?

A

sigma1, sigma2, beta, beta’, and one omega subunit

28
Q

what can’t the core enzyme do without a sigma subunit?

A

it cannot bind the promoter or initiate RNA synthesis

29
Q

what are the other types of sigma subunits called?

A

alternative sigma subunits

30
Q

what do alternative sigma subunits do?

A

alter core enzyme conformation in slightly different ways to facilitate association with different types of promoters

31
Q

what is a promoter?

A

a double stranded DNA sequence that the RNA polymerase binding site

32
Q

where is the promoter located for bacterial (prokaryotic) things

A

a short distance upstream of the coding sequence. within a few nucleotides of +1

33
Q

where does the RNA polymerase bind to the consensus sequence?

A

within the region of the promoter

34
Q

what is the prinbow box or -10 consensus sequence?

A

a six base pair region in the promoter at the negative 10 nucleotide
5’-TATAAT-3’

35
Q

what is the -35 consensus sequence?

A

5’-TTGACA-3’

36
Q

what does RNA Polymerase bind to in a prokaryotic promoter sequence?

A

-10 and -35 sequences and occupies the space between and around them

37
Q

Transcription Initiation

A
  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
Q

what does alternative sigma subunits allow for?

A

holoenzyme binding to variant promoters

39
Q

how long is the transcrption bubble in trancription elongation?

A

18 nucleotides

40
Q

when do the sigma subunits dissociate?

A

after the first 8 to 10 RNA nucleotides are polymerized

41
Q

what happens to the core enzyme after trascription is completed?

A

the 3’ end of the RNA trails off the core enzyme and becomes dissociates from the DNA

41
Q

what is a dna termination sequence

A

a repeating sequence that teriminates the transcription in bacteria

42
Q

intrinsic termination

A

the repeated sequence induces secondary structures in the newly formed RNA that induce termination

43
Q

rho-dependent termination

A

uses a different termination sequence and the rho protein (small GTPase)

44
Q

what is the rho enzyme do?

A

an additional enzyme that helps induce termination

45
Q

how does most bacteria termination occur?

A

via intrinisc termination

46
Q

what is a hairpin

A

a short stem-loop structure

47
Q

what is intrisic termination

A

where termination sequences include an inverted repear followed by a string of adenines

48
Q

what is the hairpin followed by?

A

a series of Us in the mRNA that causes the RNA polymerase to slow down and destabalize

49
Q

what induces the polymerase to release the transcript and seperate from DNA?

A

the instability caused by the slowing polymerase and the U-A base pairs

50
Q

rho-dependent termination does not have a string of ______

A

uracils

51
Q

what does rho-dependent termination instead of uracils?

A

rho utilization site (rut site) a stretch of about 50 nucleotides rich in cytosine

51
Q

how are rho proteins activated?

A

by ATP binding to one of the functional domains, faciliating binding to the rut site

52
Q

rna polymerase I

A

transcribes three ribosomal RNA genes

52
Q

how many polypeptides do rho proteins contain?

A

6 identical polypeptides with two functional domains each

52
Q

rna polymerase II

A

transcribes protein coding genes (mRNA) and most small nuclear genes

53
Q

rna pol III

A

transribes tRNA, one small nuclear RNA, and one ribosomal RNA

54
Q
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genetics (37 decks)

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