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FUN biomed and pharmo > Q2-FUN11/Transcription and regulation of gene expression > Flashcards

Q2-FUN11/Transcription and regulation of gene expression Flashcards

1
Q

At what steps of transcription does regulation occur at?

A
  1. chromatin structure
  2. transciption initiation
  3. mRNA stability
  4. transcript processing
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2
Q

What are the 3 major functions of RNA within the cell?

A

copying genetic info from DNA, helps make ribosomes, help build new polypeptides

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3
Q

The structure of DNA is _____ while the structure of RNA is _________

A
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4
Q

DNA is located in the _______ while RNA is located in the _________

A
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5
Q

What types of RNAs are involved in transcription and translation?

A

mRNA, rRNA, tRNA

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6
Q

What are snRNAs?

A

small nuclear RNAs, they function in a lot of nuclear processes, inc. splicing pre-mRNA

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7
Q

What are ncRNAs?

A

they are non-coding RNAs. They function is a lot of different cellular processes, inc. regulation of gene expression. They also are involved in X-chromosome inactivation and protein transport.

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8
Q

What distinct signals are encoded within the DNA sequence of a gene?

A

start and stop

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9
Q

Where does transcription start and end at?

A

it starts at the transcription start site (TSS, located at the end of the promoter region) and ends at the terminator site.

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10
Q

Each gene has a _________ promoter

A

unique

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11
Q

What are the two types of promoters?

A

basal promoter element and enhancer element

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12
Q

What is an enhancer?

A

Enhancers are regulatory DNA sequences that, when bound by proteins called transcription factors, enhance the transcription of a gene.

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13
Q

What is a basal promoter?

A

it is bound by RNA poly II and basal transcription factors

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14
Q

What is an example of a basal promoter?

A

TATA box - most common

2-30 base pairs from transcriptional site

can bind basal TFs and RNA poly II

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15
Q

What typically catalyses transcription?

A

RNA poly II

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16
Q

How does RNA poly II work?

A

it transcribes one of the 2 DNA strands of the gene. it reads its template from 3’ to 5’ and makes an RNA copy of 5’ to 3’.

It incorportates AGCU when making the mRNA copy of the DNA

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17
Q

What are the 3 stages of transcription?

A

initiation, elongation, termination

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18
Q

What happens in initiation of transcription?

A

RNA poly II binds to DNA and unwinds a 17-18 bp segment of the promoter. This segment is called the open complex.

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19
Q

Explain what happens during elongation of transcription.

A

RNA Pol II moves along the template until it reaches the terminator region. During this phase, an area of DNA under the RNA pol II stays unwounded. This unwounded part is called the transcription bubble and it moved along the DNA.

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20
Q

What 2 things happen during temination?

A
  1. transcription continues beyond the protein coding region (3’ UTR)
  2. endonuclease (enzyme that cleaves mRNA) cleaves abt 20 base pairs beyond the sequence
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21
Q

What is the primary transcript?

A
22
Q

What are hnRNAs?

A

heterogenous nuclear RNA. It refers to the large pre‐mRNAs of various nucleotide sequences that are made by RNA Polymerase II, and processed in the nucleus to become cytoplasmic mRNAs.

23
Q

What are the 2 types of post translational mRNA processing?

A

5’ capping and 3’ poly A tail

24
Q

explain 5’ capping.

A

add a 7-methyl-guanosine residue to the 5’ end of the mRNA.

the mRNA is catalysed by guanylyltransferase (capping enzyme) and then methylated by a methyltransferase enzyme

the 1st and 2nd nucleotides are also methylated

25
Q

Why is 5’ capping important?

A

it protects the mRNA from degraded by exonucleases, promotes nuclear export, helps with the recognition of translational machinery

26
Q

explain the 3’ poly A tail addition to the primary transcript.

A

after the polyadenylation signal sequence has been recognized (and endonuclease has been recruited and mRNA has been cleaved), Poly(A) polymerase adds abt 40-250 adenines to the cleaved 3’ end

27
Q

What determines the stability of mRNA?

A

3’ UTR (untranslated region) sequence determines the stability of mRNA

28
Q

What is the poly A tail on an mRNA transcript stabilized by?

A

poly-A binding protein (PABP), binds approx 30 residues

29
Q

What happens to the poly A tail over its lifetime?

A

it gets gradually shortened

30
Q

What happens when the PABP can no longer bind?

A

the 30 base pairs get degraded

31
Q

Which part of the mRNA transcript gets spliced out?

A

introns get spliced out

32
Q

what carries out the splicing of introns in an mRNA transcript?

A

spliceosome

33
Q

what is a spliceosome made out of?

A

large comple of RNA and proteins, small nuclear RNAs + proteins = small nuclear ribonuceloproteins (snRNPs)

34
Q

what do snRNP’s do?

A

the facilitate splicing by located specific seqences at the end of each intron, cutting them out, and rejoining the exons together

35
Q

explain how snRNP’s work.

A
36
Q

Explain differential splicing/exon shuffling.

A

it is a way for a single primary transcript to be spliced into different mRNAs, by the inclusion of diff sets of exons

https://www.youtube.com/watch?v=JEylX4cQvpg

37
Q

What are the 2 types of genes?

A

constitutive genes and inducible genes

38
Q

Are constitutive genes essential?

A

yes they are essential and nessessary for life

39
Q

Are constitutive genes constantly expressed or only on some of the time?

A

since they are nessessary for life, they are continuously expressed

40
Q

What are inducible genes?

A

inducible genes are genes that only need to be turned on some of the time when they are required

41
Q

What do inducible genes determine?

A

they determine development and tissue specificity

42
Q

What do inducible genes allow cells to do?

A

they allow cells to respond to the environment

43
Q

Inducible gene expression is controlled by _________________ proteins

A

transcription factor

44
Q

what is an example of Inducible gene expression is controlled by transcription factor proteins?

A

steroid hormones bind to steroid receptor transcription factors. these form a homodimer that recognizes and binds to specific DNA sequences within the DNA code

45
Q

transcription factors are proteins that bind to a specific ________ in the gene promoter

A

DNA sequence

46
Q

Transcription factors control the rate of ______

A

transcription

47
Q

What on the transcription factor determines the rate of transcription?

A

binding sites

48
Q

What do miRNAs do?

A

they are small strands of RNA (20-25 nucleotides) that regulate gene expression

49
Q

miRNAs are transcribed from _____________

A

DNA

50
Q

do miRNAs make proteins?

A

no they are non-coding RNA

51
Q

the primary function of miRNA is to ________ gene expression

A

down regulate

52
Q

what are the 2 ways miRNA blocks gene expression?

A

it promotes RNA degradation by binding to complementary sequences in 3’ UTR and induces degradation

it binds to mRNA and blocks translation

FUN biomed and pharmo (8 decks)

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