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BIOL 1020 > Gene Expression: Transcription- lecture #19 > Flashcards

Gene Expression: Transcription- lecture #19 Flashcards

1
Q

DNA –> mRNA is what?

A

transcription

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2
Q

mRNA –> protein is what?

A

translation

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3
Q

what is the central dogma of biology?

A

DNA –> mRNA –> protein
descriptor of transcription and translation

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4
Q

what contains information for the amino acid sequence?

A

genes

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5
Q

are all proteins enzymes?

A

no, there are diverse functions

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6
Q

one gene can be transcribed into RNA but RNA is not always used to produce protein, why?

A

RNA thats made can be a dead end/ functional RNA they stop after making RNA cause they only have one job with RNA

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7
Q

what is functional RNA?

A

rRNA, tRNA

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8
Q

what do many proteins consist of?

A

many polypeptide subunits

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9
Q

what are polypeptide subunits?

A

peptide units assembled into protein normally in the quaternary structure
the different structures (primary, secondary, tertiary, quaternary)

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10
Q

what is an example of a peptide subunit?

A

hemoglobin

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11
Q

how can one gene be used to produce closely related polypeptides?

A

via alternative splicing

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12
Q

overall what forms RNA in transcription?

A

DNA template strand of a gene forms RNA

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13
Q

what separates the two DNA strands in transcription?

A

RNA polymerase

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14
Q

while separating the DNA strands what does RNA polymerase also do? what does it form?

A

covalently joins nucleotides to one another according to the DNA template forming phosphodiester bonds

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15
Q

what sequence is complementary to the DNA template?

A

RNA sequence

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16
Q

RNA polymerase can only join nucleotides in what direction? (3’ to 5’) or (5’ to 3’)

A

5’ to 3’

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17
Q

what is a primer?

A

RNA

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18
Q

transcription begins at sites on the DNA template called what?

A

promotors

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19
Q

how does the promotor get initiated?

A

RNA polymerase attaches and initiates transcription

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20
Q

what ends the transcription in prokaryotes?

A

terminator sequences
(more complex in eukaryotes because they’re more complicated)

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21
Q

why do we need a terminator in transcription?

A

or else you’ll create too much information that is not relevant to the protein you want to make
(don’t want to waste energy for no reason!)

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22
Q

what does upstream refer to?

A

regions before the gene

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23
Q

what does downstream refer to?

A

regions after the gene

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24
Q

are promoter sequences located upstream or downstream?

A

always upstream

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25
Q

what is the transcription unit?

A

the stretch of DNA that is transcribed (before the gene)

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26
Q

how many RNA polymerase do prokaryotes have?

A

one

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27
Q

how many RNA polymerase do eukaryotes have?

A

more than one

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28
Q

what assembles mRNA (protein)?

A

RNA polymerase II

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29
Q

what do RNA polymerase I and III assemble?

A

RNA that will not be made into protein

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30
Q

what are the 3 stages of transcription?

A

initiation
elongation
termination

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31
Q

what contains the transcription start point?

A

promoter region upstream of the gene

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32
Q

what does the promoter extend upstream from the transcriptional start point?

A

several dozen nucleotides

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33
Q

why does RNA polymerase bind at such a precise location on the promoter?

A

if its not in the right location you will miss/lose information

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34
Q

what determines where transcription begins and which of the two strands will serve as a template?

A

RNA polymerase orientation on the promoter

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35
Q

in prokaryotes RNA polymerase binds to what directly?

A

the promoter, doesn’t need help

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36
Q

what factors mediate the binding of RNA polymerase at the beginning of transcription?

A

transcription factors

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37
Q

when does RNA polymerase II bind?

A

once transcription factors are in position on the promoter

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38
Q

what is the process of RNA polymerase called?

A

transcription initiation complex

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39
Q

what is a TATA box?

A

series of 4 nucleotides
important in forming the initiation complex

40
Q

Once the RNA polymerase binds what happens?

A

DNA unwinds and transcription begins

41
Q

what happens during elongation?

A

RNA polymerase keeps moving along the DNA template untwisting the sequence

42
Q

how many DNA nucleotides of the template are exposed at a time in elongation?

A

10-20 DNA nucleotides

43
Q

why does elongation not expose the whole gene at once?

A

too disorganized

44
Q

why does elongation not expose the whole gene at once?

A

too disorganized

45
Q

elongation adds nucleotides at what end of the growing RNA segment?

A

3’ end

46
Q

what does newly synthesized RNA do?

A

peels away from the DNA template

47
Q

what happens when the RNA peels away from the DNA template?

A

double helix reforms

48
Q

how many nucleotides per second are transcribed in eukaryotes?

A

40 nucleotides per second

49
Q

why do many RNA polymerase enzymes work on a DNA template at once?

A

increases the number of mRNA transcripts produced
increases the amount of protein produced

50
Q

how does termination occur in prokaryotes?

A

occurs via a terminator sequence in DNA
(causes the polymerase to detach once it has been transcribed)

51
Q

how does termination occur in eukaryotes?

A

RNA polymerase II transcribes a polyadenylation signal on the DNA template (AAAAAA)

52
Q

where does termination occur in eukaryotes?

A

pre-mRNA (immature/incomplete mRNA)

53
Q

when do proteins will cut the mRNA free from the polymerase after how many nucleotides?

A

10-35 nucleotides after the transcription of this sequence

54
Q

when does further processing occur after the mRNA is cut?

A

after the pre-mRNA is released
(processed further to become mature mRNA then become protein)

55
Q

where is pre-mRNA made and modified?

A

eukaryotic nucleus

56
Q

RNA processing modifies what?

A

5’ end and the 3’ end
interior of the mRNA molecule

57
Q

what does splicing do?

A

removes internal segments of the mRNA

58
Q

what happens to the remaining segments of mRNA do?

A

they’re joined together

59
Q

what does the 5’ end of the mRNA transcript recieve?

A

5’ cap
guanine nucleotide= 5’ cap

60
Q

what does the 3’ end of the mRNA transcript recieve?

A

poly-adenine tail

61
Q

how many adenine nucleotides will be added to the 3’ end?

A

50-250 adenine nucleotides

62
Q

new mRNA (mature) is exported from the nucleus and used for what?

A

used in the cytoplasm for translation

63
Q

what is apart of the coding section?

A

mRNA

64
Q

what do modifications do? (2)

A

prevent cytoplasmic degradation of the mRNA
allow the ribosome to recognize the mRNA segment and attach

65
Q

why do we put all these extra groups (modifications) into the mRNA?

A

because RNA viruses can infect the cell, modifications allow us to self identify RNA

66
Q

what are untranslated regions (UTR)?

A

mRNA contains 5’/3’ UTRs
UTR: they are not translated into protein

67
Q

what do untranslated regions do?

A

assist ribosome binding

68
Q

what does RNA splicing do?

A

removes large chunks of mRNA in the nucleus (before export to cytoplasm)

69
Q

how many nucleotides are inthe mRNA primary transcript (pre-mRNA)

A

~27,000

70
Q

how many nucleotides are in the final mRNA (mature RNA)?

A

1200 nucleotides

71
Q

the coding segment gets translated into protein, if the coding segment has 1200 nucleotides how many amino acids will be in the protein product?

A

1200/3 = 400 amino acids

72
Q

what are introns?

A

long non-coding stretches of mRNA that are removed from the primary transcript

73
Q

what are exons?

A

interspersed between the coding segments
they stay in the final mRNA
eventually translated into protein

74
Q

what does RNA polymerase II do?

A

transcribes the entire DNA gene into pre-mRNA

75
Q

when do introns get removed?

A

prior to cytoplasmic export

76
Q

what is joined together to form the continuous mRNA sequence?

A

exons

77
Q

what happens to released introns?

A

readily degraded

78
Q

what dictates splicing?

A

short nucleotide sequences at the start of each intron

79
Q

what are snRNPs and what do they do?

A

small nuclear ribonucleoproteins
Recognize the splice sites in pre-mRNA

80
Q

what are snRNPs comprised of?

A

small nuclear RNA (snRNA) and proteins
snRNA ~150 nucleotides + protein

81
Q

where are snRNPs located?

A

eukaryotic nucleus

82
Q

what is a splicesome?

A

snRNPs come together with different proteins forming a splicesome

83
Q

what do snRNAs do?

A

catalyze intron removal and are important in recognition of splice sites

84
Q

what are ribozomes?

A

RNA with enzyme function
enzymes are normally proteins, this is an exception

85
Q

what does intron RNA do?

A

acts to catalyze its own removal
does not require protein

86
Q

according to sequence complementarity what can ssRNA do?

A

fold back on itself which provides necessary 3D structure

87
Q

why is it important for ssRNA to fold back on itself?

A

forms catalytic activity

88
Q

what is used in catalysis?

A

certain RNA bases are specifically used

89
Q

what does hydrogen bonding ability of RNA do?

A

allows the molecule to recognize and attach to active site

90
Q

RNA of spliceosome and RNA of the transcript are what to each other?

A

complementary to one another

91
Q

what does 1 gene allow for?

A

2 or more polypeptides

92
Q

what is alternative splicing?

A

removal of different exons creates protein variants

93
Q

are introns always removed?

A

yes

94
Q

why is alternative splicing highly efficient?

A

allows us to have fewer genes (simplified genome) than we would otherwise require in our genome

95
Q

the number of proteins that we can produce far outnumbers what?

A

the number of genes that we encode

96
Q

what is alternative splicing likely responsible for?

A

the various domains of a particular protein

97
Q

what are domains?

A

different axons give us different domains
look at pic on brainscape folder (domains)

BIOL 1020 (16 decks)

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