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Biol 243 Midterm > 2B > Flashcards

2B Flashcards

1
Q

Brief overview of transcription

A
  1. Initiation
    2.Élongation
  2. Termination
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2
Q

What is an organisms phenotype dependent on

A

-cell number
-cell type
-cell fxn

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3
Q

Do cells have identical genome

A

Yes.. difference in expression (transcription)

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4
Q

Gene component

A

Promoter+transcriptional unit

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5
Q

Promoter in gene?

A

DNA sequence (include TATA box)-> where transcription begins on chromosome

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6
Q

Where is promoter on gene???

A

Upstream/5’ of transcriptionalstart point of nontemplate/coding DNA

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7
Q

Transcriptional machinery role

A

Recognize and bind to promoter to initiate transcription

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8
Q

Transcriptional machinery??

A

(RNA poly and transcription factors)

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9
Q

Transcriptional unit??

A

Part of gene copied into RNA (RNA coding region)

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10
Q

Where is the first ribonucleotide added in transcription

A

Transcription start site

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11
Q

Where is last ribonucleotide added in transcription

A

Transcription termination site

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12
Q

RNA poly use

A

-synthesize RNA transcript in 5’->3’ sense (add to 3’-OH.. read DNA template in 3->5)
-NO primer needed to initiate (can initiate from scratch)
-unwind and rewind DNA helix during RNA synthesis

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13
Q

3 types of RNA poly

A
  1. RNA Pol I: rRNA
  2. RNA Pol II: mRNA
  3. RNA Pol III: tRNA
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14
Q

RNA pol I use

A

.rRNA-> transcription of noncoding gene (rRNA)

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15
Q

RNA Pol II

A

Transcription of coding RNA (mRNA)

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16
Q

RNA pol III

A

.tRNA… transcription of non coding RNA (tRNA)

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17
Q

Step 1: transcriptional initiation

A

-mediated by DNA binding protein… specific regulatory sequence of gene (RDS)

2 types:
1. General transcription factor bind to promoter=> recruit RNA poly II in low basal level transcription
2. Transcriptional activator protein bind to enhancer region (far from promoter= DNA looping brings mediator and RNA poly to promoter=high level transcription)

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18
Q

Step 2: transcriptional elongation

A

-RNA poly moves along template DNA (3->5)
-DNA unwound in front of moving RNA poly and reannealing behind transcription Bubble
-ribonucleotide added to 3’ end of RNA transcript (synthesis in 5’->3’)
-growing RNA transcript displaced from DNA template allows reannealing back into dsDNA

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19
Q

Step 3: transcriptional termination

A

-5’ sequence in DNA template=> termination after transcribed into RNA

  1. Rho-independent termination (rhohelicase)-> prokaryotes: terminator sequence in mRNA pairs with itself= G-C hairpin= RNA poly dissociate
  2. Rho-dependent termination (rho helicase)-> prokaryotes: terminator sequence in mRNA is recognized and bound by rhohelicase=> unwind RNA from template DNA and RNA poly
  3. Cleavage and polyadenylation specific factor (eukaryotes): poly-A-sequence in mRNA signals CPSF cleave completed mRNA transcript= separate fromRNA poly
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20
Q

DNA molecule ds or as

A

Ds

21
Q

RNA molecule ds or ss

A

Ss

22
Q

WHERE does DNA replication occur

A

Entire genome

23
Q

Where does transcription occur

A

Select location in genome (aka gene)

24
Q

How many replications per cycle for DNA replication

A

Replicate genome once/cell cycle

25
Q

How many RNA synthesized. In transcription

A

Many RNA in many copies and copies vary through genome

26
Q

DNA poly need or no need primer

A

Need cannot synthesize from scratch

27
Q

RNA poly need primer or not

A

No, can synthesize de novo

28
Q

DNA replication end product??

A

Daughter strand base paired wth parental template strand (semi conservative replication)

29
Q

Transcription end products

A

RNA product is detached and ss (NOT remain base paired to template DNA)

30
Q

Synthesis of new DNA in what direction

A

DNA replication in 5->3

31
Q

Synthesis of RNA in what direction

A

5->3 (transcription)

32
Q

Postranscriptional regulation of gene expression brief overview

A

Process mRNA for stability and proper translation

1.5’capping
2. 3’ polyadenylation
3. Splicing

33
Q

Are the ends of prokaryotic and eukaryotic mRNA translated

A

NOO….5’ and 3’ are untranslated region
-UTR regulate mRNA stability and translationalefficiency

34
Q

What does 5’-UTR have

A

Ribosome binding site (RBS)

-shine dalgarno sequence in prokaryotes
-Kodak box sequence in eukaryotes… fxn in translationalinitiation

35
Q

ORF

A

Open reading frame

Region of mRNA translated and includes start and stop codons at borders

36
Q

Going from DNA to polypeptide what is cut

A

DNA: promoter+ transcriptionalunit
DNA->mRNA
.mRNA: 5’UTR+ORF+ 3’UTR
RNA->polypeptide
Polypeptide: N-amino acid-C

37
Q

Postranscriptionalmods of eukaryotic pre-mRNA

A

Pre-mRNA has processing in nucleus= mature translatable mRNA

  1. 5’cap- moded Guanosine triphosphate added to5’end of mRNA and act as ribosomebinding site and protect mRNA from degradation
  2. Poly (A) tail: string of adenine nucleotides added to 3’ end of mRNA by poly-A-polymerase(protect mRNA from degradation and increase translational efficiency
    3.introns are removed/spliced during pre-mRNA processing= translatable mRNA
38
Q

Posttranscriptional processing from pre-mRNA to mRNA

A

Pre-mRNA has coding segments and UTR (exon) and non coding segment (intron)

Remove intron by splicing-> ORF (codon and UTR)

.mRNA exported from nucleus intro cytoplasm (associate with ribosome)

39
Q

.mMRNA splicing

A

Remove intron from pre-mRNA and joining exons=>mature mRNA

Non coding segment (intron) spliced from pre-mRNA.=> UTR+ exons (codon) left in mature mRNA

Splicing by spliceosome (made of 5 noncoding RNA (snRNA)… several proteins (snRNPs… small ribonucleoprotein)

  1. Bind to intron-exon junction
    2.loop intron out of pre-mRNA and bring exon closer
  2. Clip intron at exon boundary
    4.join exons
40
Q

Alternative splicing

A

Generate diff proteins from 1 gene

Splicing in diff combos= 2+ diff mRNA from gene= severalrelated protein products (isoforms)

-diff isoforms made in diff tissues from same genes producing tissue specific genotype
-increase # and variety of proteins encoded by genome

41
Q

Posttranscriptional regulation by RNA interference

A
  1. microRNA transcribed by RNA Pol II, siRNA (small interfering RNA) also transcribed
  2. miRNA/siRNA precursor cleaved to ds RNA (substrate of RISC-RNA induced silencing complex) by dicer RNAse
  3. RISC unwind 1 RNA strand which attracts binding of complementary mRNA
  4. Binding of mRNA to RISC interferes with translation initiation/induces mRNA degradation (repress gene expression)
42
Q

Transcriptional regulation

A

Control of mRNA synthesis
Transcriptional rate depend on speed of transcriptionalinitiation (promoter strength)

43
Q

Postranscriptional regulation

A

Process mRNA (affect stability and translational efficiency)
Stability of mRNA depend on presence of 5’CAP and length of poly-A-tail

44
Q

What does the expression level of a gene depend on

A

-abundance of mRNA
-nucleotide sequence
-translation

45
Q

What does abundance of RNA depend on

A

-rate of synthesis (transcription)
-degradation ofmRNA (Postranscription)

46
Q

DNA transcriptionalregulation

A

-chromatin remodeling=> accessible for transcription
-regulatory event at gene promoter and regulatory sequence

47
Q

DNA postranscriptional regulation

A

-variation in pre-mRNA processing
-removal of masking protein
-variation in rate of mRNA breakdown
-RNA interference

48
Q

RNA translationalregulation

A

Variation in rate of initiation of protein synthesis

49
Q

RNA post translationalregulation

A

-variation in rate of protein processing
-removal of masking segments
-variation in rate of protein breakdown

Biol 243 Midterm (8 decks)

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