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2. Foundations of Medicine PoD > Mutations and Genetic Analysis > Flashcards

Mutations and Genetic Analysis Flashcards

1
Q

types of chromosomal abnormalities

A
  • numerical - wrong no. chromo in karyotype (not 46)
  • Structural - chromo rearranged/fused
  • Mutational - smaller scale changes (deletion/single base pair mutation)
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2
Q

common type of chromosomal abnormality

A

Trisomy (about 50% in first trimester miscarriages across all types)

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3
Q

trisomy 21

A

down syndrome

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4
Q

origin of chromo abnormalities: non-disjunction

A

Occur in failure of disjunction of meiosis e.g. not 4 cells with 4 chromo but could be 2 with 1, 1 with 2 (disomy) and 1with none (null)

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5
Q

where is the origin of non-disjunction (apart from 45,X)

A

Maternal

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6
Q

aneuploidy

A

the condition of having an abnormal number of chromosomes in a haploid set

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7
Q

give 3 autosomal aneuploidy syndromes

A
  • trisomy 21 (down syndrome)
  • Trisomy 13 (patau syndrome)
  • Trisomy 18 (Edwards syndrome)
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8
Q

trisomy 21 (down syndrome)

autosomal aneuploidy syndrome

A
  • Inc with advancing maternal age (probs due to non-disjunction problems)
  • low IQ
  • Lower life expectancy
  • Tendancy twoards Alzheimer’s in later life
  • Chromosomal findings: non-dysjunction (95%) usualy maternal, unbalanced Robertsonian translocation (4%), Mosaicism (1%)
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9
Q

trisomy 13 patau syndrome

autosomal aneuploidy syndromes

A
  • dysmorphic features and mental retardation
  • very early death
  • Non-dysjunction with maternal origin (90%), unbalanced robertsonian translocation (10%)
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10
Q

Trisomy 18 (edwards syndrome)

autosomal aneuploidy syndromes

A
  • severe developmental problems - early death
  • Non-dysjunction with maternal origin (90%)
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11
Q

give 2 sex chromosome aneuplodiy syndromes

A
  • 45,X (turner syndrome) - only single X chromo: females short stature and infertile, neck webbing
  • 47,XXY (Klinefelter syndrome): tall stature, long limbs, males infertile, mild learning difficulties
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12
Q

give some common chromosomal structural abnormalities

A
  • balanced or unbalanced rearrangements
  • Translocations (reciprocal or robertsonian)
  • Deletions
  • Insertions
  • Inversions
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13
Q

reciprocal translocations

A

invilving breaks in 2 chromo with formation of 2 new derivative chromo

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14
Q

Robertsonian translocation

A

fusion of two acrocentric chromosomes - results in loss of short arms

acrocentric - centromere at ends of chromo

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15
Q

what is a key feature of a balanced translocation

A

No DNA lost

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16
Q

key feature of unbalanced translocation

A

a translocation between chromosomes resulting in the gain or loss of genetic material, likely resulting in a chromosomal condition

17
Q

robertsonian translocation carrier outcomes

A

increased risk for infertility, spontaneous abortions, or chromosomally unbalanced offspring.

18
Q

Deletion

A

break in chromosome and loss of genetic material

19
Q

Inversion

A

Balanced rearrangements - no phenotypic effect

20
Q

what 2 different things can mutations act on

A

non-coding or coding sequences

21
Q

types of mutation acting of coding sequences

A
  • silent (CGA arg to CGC arg)
  • Missense (CGA arg to GGA glc)
  • Nonsense (CGA arg to TGA stop)
  • Frameshift (deletion/insertion)
22
Q

how can we detect mutations

5

A
  • PCR
  • Gel electrophoresis
  • Restriction fragment length polymorphism (RFLP) analysis
  • Amplification refractory mutation system (ARMS)
  • DNA sequencing
23
Q

Things required for PCR

A
  • sequnce info
  • corresponding oligonucleotide primers
  • DNA
  • nucleotides
  • DNA polymerase (thermally resistant)
24
Q

PRC technique

(brief)

A
  1. Denature DNA
  2. Anneal (primers bind?)
  3. Extennd
25
Q

summarise gel electrophoresis

A
  • seperate DNA fragments bu size
  • apply electric field
  • DNA -vely charged
  • Seperate by size through agarose gel matrix
  • visualise DNA fragments
26
Q

advantages of PCR

A
  • speed
  • ease of use
  • sensitivity
  • robuse
27
Q

applications of PCR

just list a ton of em

A
  • DNA cloning
  • DNA sequencing
  • In vitro mutagenesis
  • Gene identification
  • Gene expression studies
  • Forensic medicine
  • Typing genetic markers
  • Detection of mutations
28
Q

ARMS

name, what does it allow us to do?

A

amplification refractory mutatuon system - allows us to see if individual has mutation at specific site if we know what it is

29
Q

Pros/cons of ARMS

A

Advantages:
* Cheap
* Labelling not required (flourecent, redioactive)
* Electrophoresis required
* Primer design critical

Disadvantages:
* need sequence information
* Limited amplification size

30
Q

restriction endonucleases

A

family of enzymes that each recognise and cut DNA at a specific sequence recognition site

31
Q

RFLP analysis

(Restriction fragment length polymorphism)

A

Enzyme can recognise/cut normal DNA but not mutated DNA - assay shows lines - lack of line = mutation

32
Q

Pros/cons of RFLP

A

Advantages:
* Simple
* Cheap
* Non-redioactive

Disadvantages:
* Required gel electrophoresis
* Not always feasible

33
Q

what does DNA sequencing rely on

A

OH group on deoxynucleotide - uses dideoxynucleotides

34
Q

Advantages/limitations of DNA sequencing

A

Advantages:
* Great for mutation detection
* automation and high throughput

Limitations:
* Expensive equipment
* Poor quality sequence read (first part good then deteriorates at about 800 bases)

35
Q

What factors would contribute to the ultimate test method

weird one but…

A
  • direct test
  • quick and easy
  • cheap
  • sensitive
  • specific

2. Foundations of Medicine PoD (28 decks)

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