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Med Gen Flashcards

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1
Q

How can a frameshift result in no protein production?

A

Change in reading frame
likely induction of premature termination codon
Induction of Nonsense Mediated Decay Pathway

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2
Q

List the stages of the cell cycle?

A

G0, G1, S, G2, M

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3
Q

What occurs at G0 in the cell cycle?

A

Quiescent phase- metabolically active but not dividing

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4
Q

What occurs at the G1 phase of the cell cycle?

A

cells are metabolically active and growing

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5
Q

Wha occurs at the S phase of the cell cycle?

A

Synthesis of organelles for mitosis to occur

DNA synthesis and replication

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6
Q

What occurs at the G2 phase of the cell cycle?

A

Protein synthesis
Growth
Prepare to divide

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7
Q

What occurs at the M phase of the cell cycle?

A

Mitosis occurs

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8
Q

What are snRNP’s?

A

small nuclear ribonucleoproteins

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9
Q

What is the function of U2AF?

A

U2 Auxiliary Factor
binds to polypyramidine tract
Required for binding of U2 to branch site

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10
Q

What is the function U1?

A

Binds to 5’ donor site

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11
Q

What is hnRNP?

A

Heterogeneous Ribonucleoprotein particles

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12
Q

What does hnRNP bind?

A

Intron splicing silencer elements
Exon splicing silencer elements
(ISS’s and ESS’s)

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13
Q

What effect do hnRNP’s have on splicing?

A

Inhibit Splicing

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14
Q

What are SR proteins?

A

Serine Argenine Rich Proteins

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15
Q

What do SR proteins bind?

A

Intron Splicing Enhancer elements
Exon Splicing Enhancer elements
(ISE’s and ESE’s)

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16
Q

What is a presymptomatic test?

A

Before a patient is showing signs predicting what will happen in the future

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17
Q

What is a diagnostic test?

A

Patient showing symptoms of a particular disease

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18
Q

What age is a presymptomatic test usually done?

A

18 years old minimum

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19
Q

Why would a presymptomatic test be done on someone under 18?

A

If test could directly benefit by allowing medical/surgical intervention

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20
Q

What are the key differences between apoptosis and necrosis?

A

Apoptosis:

  • Programmed
  • normal cellular process
  • No inflammatory response
  • Activated by cellular factors (p53)

Necrosis

  • Unprogrammed
  • Associated with disease
  • Associated with inflammatory response
  • Activated by external factors (viruses)
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21
Q

Why is a consangenuieous relationship more likely to result in offspring with genetic abnormalities?

A

Every individual has rare deleterious, recessive mutations

when parents related, it increases chance of both parents carrying the same mutation

Increased risk in offspring inheriting a mutation on both chromosomes

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22
Q

Define intron

A

region of transcript that is not fully processed RNA as it

excised during splicing

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23
Q

Define exon

A

region of transcript that is fully included in processed mRNA

Generates transcripts that are coding and translated into proteins OR are non-coding transcripts that aren’t translated

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24
Q

Define promoter

A

A cis-acting regulatory DNA element that binds upstream of a transcription unit and binds to RNA polymerase

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25
Define 3' UTR
The untranslated region between a stop codon and the poly A tail
26
Define coding region
Entire exonic sequence that is translated, not the 5'UTR or 3' UTR
27
What is Anticipation?
Disease severity increases with each generation
28
Define 5' UTR?
region between the transcription and translation start site
29
Define start codon
3 base pairs that result in the initiation of ribosomal translation
30
Define intergenic region
Regions of the genome that do not encode for protein-encoding genes
31
What is mtDNA?
mitochondrial DNA
32
Describe Transcription (3)
RNA polymerase makes pre-mRNA from template DNA strand
33
Describe splicing (3)
Splicesomal proteins bind to pre-mRNA template Intron removed in the form of a lariat 2 exons ligated to form a mature mRNA
34
Define epigenetics:
Reversible regulation of gene expression through changes in DNA methylation and chromatin structure, independent of DNA sequence
35
What are 2 examples of epigenetic modifications?
Histone modifications | Methylation at CpG sites
36
Define the Nonsense Mediated pathway (5 points)
-Exon Junction Complex deposited at sites where splicing has occurred -UPF1,2,3 bind to EJC -Translation release factors associate with the ribosome at the site of premature termination - Release factors interact with UPF1 mRNA is decapped, deadenylated and degraded
37
What does RNA polymerase I produce?
rRNA
38
What does RNA polymerase II produce?
mRNA
39
What does RNA polymerase III produce?
tRNA and snRNA
40
What are the 5 key trnascription Factors?
``` TFIID TFIIB TFIIF TFIIE TFIIH ```
41
What premature ageing syndrome can be caused by mutations in TFII complex genes (TFIIH)?
Cockayne's Syndrome?
42
What triggers the change of the initiation complex to the elongation complex in transcription?
Gross structural changes in RNA polymerase II
43
What are the 3 components of RNA Processing?
- 5' Capping - Splicing - Polyadenylation
44
What is the 5' cap?
Modified G residue with unusual 5' to 5' bond
45
What is the function of the 5' cap?
prevention of 5' exonuclease degredation | identified as normal 3' mRNA by degredation machinary
46
How is the 5' cap used to regulate nuclear export?
Cap binding complex is recognised by nuclear pore for export
47
What are the 4 steps of the mRNA splicing reaction?
- Adenine residue in intron attacks 5' splice site - The cut 5' end of intron, binds to Adenine, creating a loop - Released 3'OH end of exon, reacts with start of the next exon sequence, joining the 2 - Intron released as a 'lariat' and then degraded
48
What effect do SR proteins have on splicing?
Enhance Splicing | (by binding to Intron/exon Splicing Enhancer Elements
49
What is the role of CPSF in polyadenylation/?
- Cleavage + Polyadenylation Specificity factor | - Identifies Poly A signal
50
What is the role of CFI+CFII?
- Cleavage Factors | - Cut mRNA to allow addition of PolyA tail
51
What is the role of CstF?
- Cleavage stimulation Factor | - promotes cleavage by CFI+CFII
52
What is the role of PAP?
- Polyadenylate Polymerase | - Adds PolyA
53
What is the role of PABI+PABII?
- PolyA bindin proteins | - regulate mRNA stability
54
How are RNA's directed to specific locations?
by sequences in the 3' UTR of transcript
55
What 2 subunits make up the 80S ribosome?
40S and 60S
56
What are the 3 stages in translation?
1. Initiation 2. Elongation 3. Termination
57
What is involved in translation initiation?
Initiation factors, poly A binding protein, and the association of the ribosomal proteins
58
what is involved in Translation elongation?
- delivery of aa's in correct sequence by tRNA's - peptide bonds form between adjacent aa's - polypeptide chain
59
What occurs during translation termination?
- Termination codon encountered - Binds release factors (eRF1) - Final polypeptide bond is hydrolysed - polypeptide released
60
What proteins determine RNA turnover?
- RNA Binding Proteins (RBP's)
61
What is the role of RBP's?
bind specific sequences in transcripts that regulate RNA stability
62
What is the role of AU rich elements (ARE's) in RNA degredation?
bind to RBP's to elicit degredation
63
What do C-rich elements bind to, to stabilise mRNA's?
AlphaCP Proteins

Medical Genetics (2 decks)

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