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Molecular Diagnostics > Lecture 2: Gene Expression: Transcription > Flashcards

Lecture 2: Gene Expression: Transcription Flashcards

1
Q

DNA directed RNA synthesis from a DNA template
by a DNA-dependent RNA polymerase

A

Transcription

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2
Q

starting point of gene expression

A

transcription

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3
Q

Eukaryotic cell
– DNA to message is nuclear
– protein synthesis is ___________

_______ mechanism is necessary

A

cytoplasmic

  • Transport mechanism is necessary
  • mRNA translocate from nucleus to cytoplasm
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4
Q

Structure and Properties of RNA:
* Unbranched polymer of nucleotide 5’ monophosphates linked by 3’-5’ ____________ bonds

A

phosphodiester

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5
Q

RNA is generally ______-stranded (ss) except in some viruses.

A

single

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6
Q

Structure and function of RNA:

Can fold upon itself to form ____________ regions. The filded 3D structure of RNA, like the folded proteins, can have multiple biological
functions.

A

intrastrand helical

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7
Q

Different Genes for Different RNAs include…

Types of RNA

A
  • Pre-RNA
  • mRNA
  • tRNA
  • rRNA
  • snRNA
  • snoRNA
  • miRNA
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8
Q

snoRNAs and miRNAs are extensively characterized small __________ regulatory
RNAs.

A

non-coding

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9
Q

snoRNAs and miRNAs have distinct and central ____________ roles in cells.

A

regulatory

-recent studies reveal that snoRNAs and miRNAs display similarities at numerous levels.

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10
Q
  • molecules showing both snoRNA and miRNA characteristics and functionality exist.
  • subsets of snoRNAs and miRNAs likely share a functional and ____________
    relationship.
A

evolutionary

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11
Q

Ribosomal RNA (rRNA) ___%
Transfer RNA (tRNA)___%
Messenger RNA (mRNA) __%

A

80
15
5

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12
Q

Secondary structure of RNA?

Tertiary structure of RNA?

A

stem loop(double-helical stem region) and hairpin

folding —-> pseudoknot

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13
Q

The ability of RNA to form unique _____ structures that act similarly to proteins is one of the key contributor that functional RNA can be involved in a wide range of cellular processes.

A

3D

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14
Q

RNA is synthesized on a ______ template by RNA polymerase.

A

DNA

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15
Q

NMPn + ribonucleoside triphosphate ———RNA polymerase/Mg2+
DNA template—–>

A

NMP n+1 + PPi

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16
Q

DNA to RNA is _____ polymerase

A

RNA polymerase

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17
Q

RNA to RNA by ___________

A

RNA replicase

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18
Q

RNA to DNA by ____________

A

reverse transcriptase

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19
Q

Prokaryotes:

___ polymerase / ___ subunits

A

1, 6

a2, b, b’, sigma, omega (alpha-2,beta,beta prime, sigma, omega)

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20
Q

________- subunit recognizes the promotor region of DNA that precedes the structural gene

A

Sigma (s)

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21
Q

______ subunit binds to promotor region, may serves to control the
efficiency of RNA synthesis.

A

Omega

But the overall function of omega (w) subunit is not
very clear

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22
Q

Rifampin- inhibits ____ subunit of polymerase

A

beta

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23
Q

Steps in Transcription:

RNA polymerase binds to promotor region (via specific _____ factor)

A

sigma

promotor has specific sequences

24
Q

Steps in Transcription:

DNA coding strand = ______ strand

Non-coding Strand (Template) = _______ strand

A

sense

anti sense

25
Q

Steps in Transcription:

Anti-sense is the one used in the _____ direction so RNA
chain is synthesized _____ and makes a coding strand

A

3’-5’

5’-3’

26
Q

Steps in Transcription:

Coding strand has same sequence as message, except…

A

U instead of T

27
Q

Steps in Prokaryotic Transcription?

A
  • initiation
    -elongation
    -termination
28
Q

Steps in Prokaryotic Transcription:

15-20bp bubble formed and only 1 strand is read

A

Initiation

29
Q

Steps in Prokaryotic Transcription:

Starts with a purine, then continues

A

Elongation

30
Q

Steps in Prokaryotic Transcription:

– Rho independent (intrinsic stem-loop)
– Rho dependent

A

Termination

31
Q

Eukaryotic Transcription:

Polymerase ___-nucleolus-synthesizes 45s rRNA

A

1

32
Q

Eukaryotic Transcription:

Polymerase ___-nucleoplasm, synthesizes mRNA, and others

A

II

-recognizes promotor sequence

33
Q

Eukaryotic Transcription:

Polymerase ____-nucleus, synthesizes tRNA, 5sRNA, miRNA

A

III

34
Q

________________ polymerase-synthesizes mitochondrial RNA

A

Mitochondrial

35
Q

B-thalasemmia involves a mutation of…

A

TATA before b-hemoglobin gene

36
Q

Affects rate of transcription and rate of protein production

A

Eukaryotic Promotor

37
Q

What increases the rate and frequency of eukaryotic transcription?

A

-genes have many regions upstream that have sites for additional elements to
bind
-affects tissue specific expression
-enhancer
-Steroid hormone receptors binding
-Cell signaling factors (100-5000 bp upstream)

38
Q

site of binding of regulatory proteins such as transcription factors and
hormone receptors

A

Enhancer

39
Q

(site of binding of regulatory proteins that stop transcription

A

Suppressor regions

40
Q

Hormone binding –> __________ —> enhancer —> promotor —> structural gene

A

transcription factor

41
Q

Purpose of Post Transcriptional Modifications to
Eukaryotic mRNA?

A

– Stability of mRNA
– Determines protein variation from a single message (splicing)
– Guide for the translocation of mature mRNA to cytoplasm

42
Q

a large RNA-protein complex that catalyses the removal of introns from nuclear pre-mRNA

A

spliceosome

43
Q

Types of processing for mRNA?

A

-5’ cap
-3’ poy-A tail
-splicing

44
Q
  • removal of introns
  • alternative splicing
    – tissue specific protein
    expression( a-
    tropomyosin, smooth vs
    striated muscle)
A

Splicing

45
Q

3’ poy-A tail:

A

many adenosines for stability

46
Q

5’ cap:

A

7-methyl-guanosine
to 5’ end

47
Q

Inhibitors of RNA Synthesis

A

-template binding
-polymerase binding
-alpha Amanitin (mushroom toxin)
-inhibitors of reverse transcription

48
Q

examples of inhibitors of reverse transcription

A

– AZT (azidothymidine)
– ddI (dideoxyinosine)

49
Q

a Amanitin (mushroom toxin)
– Inhibitors of euk. pol ___ and ___

A

II and III

50
Q

example of polymerase binding

A

Rifampin (b subunit)

51
Q

Example of Template binding (at transcription initiation complex to prevent elongation)

Type of substance

A

Actinomycin D

52
Q

Human Diseases Related to mRNA Synthesis?

A

alpha and beta thalassemia

53
Q

– A form of inherited autosomal recessive blood disorder characterized by abnormal
formation of hemoglobin.
– Also affect rate of globin synthesis
– US carrier rate= 7%; Mediterranean = 20%

A

Thalassemia

54
Q

a Thalassemias

A

– production of the α globin chain is affected
– 4 alleles, mostly deletions

55
Q

beta Thalassemias

Types of mutation effected

Affects production of what

What is destroyed

A

– production of the b globin chain is affected
– promotor mutations
– splicing mutations
– capping and tailing mutations
– nonsense and frame shift mutations
– dysfunctional protein is destroyed

Molecular Diagnostics (12 decks)

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