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bio 243 > Theme 2B > Flashcards

Theme 2B Flashcards

(51 cards)

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1
Q

what is an organism phenotype dependent on

A

cell number, type, function

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2
Q

growing a desired tissue type by turning on/off the appropriate genes

A

regenerative medicine

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3
Q

what is the transcriptional unit

A

the part of the gene that is copied into RNA

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4
Q

what is the promoter

A

DNA sequence (including TATA box) that specifies where transcription begins on the chromosome

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5
Q

where is the promoter located

A

immediately upstream (5’) of the transcriptional start point

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6
Q

what recognizes and binds the promoter

A

transcriptional machinery (RNA polymerase and transcription factors)

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7
Q

what do the three kinds of RNA polymerases do

A

RNA pol I: rRNA
RNA pol II: mRNA
RNA pol III: tRNA

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8
Q

what do RNA polymerases do

A

synthesizes RNA in a 5 - 3 direction, reading DNA 3 - 5. unwinds and rewinds DNA helix during RNA synthesis (helical activity)

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9
Q

what is the first type of transcriptional initiation process

A
  1. General transcription factors bind to the promoter and recruit RNA pol II resulting in low basal level of transcription
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10
Q

what are the three steps of transcription

A
  1. transcriptional initiation
  2. tanscriptional elongation
  3. transcriptionsl termination
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11
Q

what is the second type of transcriptional initiation process

A
  1. transcriptional activator proteins bind to enhancer regions distant from the promoter to cause DNA looping bringing mediator and RNA polymerase to the promoter resulting in high level of transcription
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12
Q

what is transcriptional initiation mediated by

A

direct interaction of DNA-binding proteins to specific regularity sequences of the gene (rate determining step)

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13
Q

where does the DNA-RNA hybrid happen

A

during transcriptional elongation in RNA polymerase II, there is a transcription bubble where the DNA strands separate and the RNA in synthesized

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14
Q

which end of the RNA transcript are ribonucleotides added to

A

‘3 (synthesis 5’ - 3’)

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15
Q

what happens to to DNA and RNA once out of the transcription bubble

A

RNA is displaced from DNA template strand and DNA is reannealed

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16
Q

what are th two types of transcriptional termination in prokaryotes

A
  1. Rho-independent: terminator sequence base pairs with itself and forms GC hairpin, causing RNA pol to stall and dissociate
  2. Rho-dependent: terminator sequence recognized and bound by rho helicase which unwinds RNA from template and RNA pol
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17
Q

how does transcriptional termination happen in eukaryotes

A

poly-adenylation sequence in DNA is transcribed into mRNA. it contains a cleavage site, signaling the protein complex CPSF to cleave the finished RNA transcript, which signals RNA pol to stop

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18
Q

transcription or DNA replication: molecules are single stranded

A

transcription

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19
Q

transcription or DNA replication: molecules are double stranded

A

DNA replication

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20
Q

transcription or DNA replication: occurs for the entire genome

A

DNA replication

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21
Q

transcription or DNA replication: occurs at selected locations in the genome

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A

transcription

22
Q

transcription or DNA replication: happens only once per cell cycle

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A

DNA replication

23
Q

transcription or DNA replication: happens in multiple copies and abundance varies across genes

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A

transcription

24
Q

transcription or DNA replication: requires a primer for initiation

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A

DNA replication

25
transcription or DNA replication: does not require a primer for initiation
transcription
26
transcription or DNA replication: strands remain base pairs with each other
DNA replication
27
transcription or DNA replication: strand do not remain base paired with each other
transcription (temporary RNA-DNA hybrid that separates)
28
transcription or DNA replication: synthesis occurs in a 5’ -3’ direction
both
29
what are the 3 types of post-transcriptional modifications
1. 5’ Capping 2. 3’ Polyadenylation 3. Splicing
30
by what process is expressioni regulated by small, noncoding RNAs
RNA interference
31
what are the untranslated ends of mRNAs called
5’ and 3’ untranslated regions (UTRs)
32
which UTR contains a ribosome binding site (RBS)
5’-UTRs
33
where is the Shine-Dalgarno sequence found
prokaryotes
34
where is the Kazak (box) sequence found
eukaryotes
35
what is the open reading frame
the region of mRNA that is translated and included the start and stop codons at the borders
36
what is the framework for an mRNA molecule
(5’ - UTR [RBS found here]) -> (start codon, orf, stop codon) -> (3’-UTR [no codons])
37
explain the post-transcriptional pre-mRNA modifiation process of 5’ - Capping
a modifies guanosine triphosphate is added to the 5’- end of the mRNA and acts as a ribosome binding site, and protects mRNA from degradation
38
explain the post-transcriptional pre-mRNA modifiation process of 3’ polyadenylation (poly (A) tail)
a 50-200 long string of adenine nucleotides is added to the 3’ end of the mRNA by poly-A polymerase to protect the mRNA from being degraded and increase translational efficiency
39
explain the post-transcriptional pre-mRNA modifiation process of splicing
introns are removed/spliced during pre-mRNA processing to produce translatable mRNA
40
can the newly transcribed pre-mRNA be translated into a protein
no
41
what are exons and introns
in pre-mRNA, exons include coding segments and UTRs, introns are non-coding segments
42
does splicing happen in prokaryotes
no
43
how does splicing generate the open reading frame
it removes the introns (non-coding) from the pre-mRNA to form a continuous segment of codons and UTRs
44
what carries out splicing
splicosome, made of 5 snRNAs and several proteins
45
what is alternative splicing
different combinations of exons can be removed or kept to generate two or more different mature mRNAs from a gene creating non-identical proteins
46
what are the related protein products made by alternative splicing called
isoforms
47
what % of human genes are alternatively spliced
~75%
48
what groups of non-coding RNAs are involved in RNA interference (RNAi)
mircoRNAs, transcribed by RNA pol II, and short interfering RNA, which can be of foreign origin
49
control of mRNA synthesis, rate depends on speed of initiation (promoter strength) or enhancers
transcriptional regulation
50
processing mRNA which affects its stability and translational efficiency
post - transcriptional regulation
51
what does stability of mRNA depend on
5’ cap and length of poly A tail

bio 243 (7 decks)

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