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Principles of disease > Chromosomal Abnormalities > Flashcards

Chromosomal Abnormalities Flashcards

1
Q

What is trisomy?

A

extra copies of a chromosome

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2
Q

What is monosomy?

A

A diploid chromosome complement where one lacks its homologous partner

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3
Q

What is triploidy & teroploidy?

A

Triploidy - extra set of chromosomes (total 69)
Tetraploidy - 2 extra sets of chromosomes (total 92)

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4
Q

How do numerical abnormalities mainly arise?

A

When chromosmes dont divide properly during meiosis (non-junction)

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5
Q

What is another name for trisomy 21?

A

Downs syndrome = Trisomy 21

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6
Q

What are characteristics of trisomy 21?

A

Maternal (chances increase with age)
Distinc facial characteristics
Alzhiemers in later life
IQ < 50
50-60 yr life expectancy.

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7
Q

What is Trisomy 13 called?

A

Patau Syndrome = Trisomy 13

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8
Q

Characteristics of trisomy 13?

A

Mental retardation
Dysmorphic features
Maternal
Most die in 1st year

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9
Q

What is Trisomy 18 called?

A

Edwards Syndrome = Trisomy 18

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10
Q

Characteristics of Trisomy 18

A

Severe developmental abnormalities
Most die in first month or year of life

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11
Q

What is Turner syndrome?

A

45,X
Lack of a sex chromosome from father

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12
Q

What are characteristics of 45,X (turners syndrome)?

A
  • Short stature & infertile
  • All female
  • Neck webbing & widely spaced nipples
  • 97% die at conception
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13
Q

What is 47, XXY called?

A

Klinefelter Syndrome = 47,XXY

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14
Q

What are characteristics of Klinefelter syndrome?

A
  • Tall & long limbed
  • Infertile, small testes
  • 50% develop breasts (gynaecomastia)
  • Mild learning difficulties.
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15
Q

What is a balanced translocation?

A

Non-Homologous Chromosomes break and repair with some DNA swapped
Usually fine since all DNA is present.

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16
Q

What is an unblanced translocation?

A

Parents chromosome have undergone balanced translocation.
Can form gametes that lack some material & have some duplicated

17
Q

What kind of chromosoes are affected by robertsonian translocations?

A

Those with one long arm and one short containing no coding DNA. (Acrocentric)

18
Q

How are two chromosmes fused in robertsonian translocation?

A

2 long arms are fused and short ones lost
No genetic material is lost

19
Q

What are the 2 types of deletion?

A

Terminal - DNA removed form chromosome end
Interstitial - DNA removed from inner part of chromosome

20
Q

What are the 2 types of inversion?

A

Paracentric - Part of one arm is inverted
Pericentric - DNA on either side of centromere is inverted (both arms change)

21
Q

What is polymorphism?

A

Mutations in genes with no phenotypic effect

22
Q

What are 4 sub-types of Coding mutations?

A

Silent
Missense
Nonsense
Frameshift

23
Q

What is a silent coding mutation?

A

Base changes but amino acid is unchanged

24
Q

What is a missense coding mutation?

A

One amino acid is changed to another

25
Q

What is a nonsense coding mutation?

A

One amino acid is changed to STOP codon

26
Q

How does a frameshift mutation occur?

A

Deletion or insertion shifts whole chain along

27
Q

What does PCR stand for?

A

Polymerisation Chain Reaction

28
Q

What are the 3 steps of PCR?

A

Denature, Anneal, Extend

29
Q

What is the result of PCR?

A

Two copies of DNA
Repeated many times to produce huge numbers of copies

30
Q

What does Gel Electrophoresis do?

A

Separated DNA fragments by size through agarose gel matrix
Applying electric field to -ve DNA
Can visualise DNA.

31
Q

What does ARMS stand for?

A

Amplification Refractory mutation system

32
Q

What does RFLP stand or?

A

Restriction Fragment Length Polymerisation

33
Q

How does RFLP work?

A

Certain Endonuclease always cut DNA at specific points in a chain of bases .
Uses Endonuclease then PCR to see length of cut section
Show if normal, mutant or heterozygous

34
Q

Whats another name for Sanger DNA sequencing?

A

Chain Termination method

35
Q

Why are dideoxynucleotides used in SANGER DNA sequencing?

A

Stop DNA polymersation reaction
Can analyse small section of DNA

36
Q

How can the base sequence be determined in chain termination DNA sequencing?

A

Dideoxynucleotides dyed with fluorescent dye
Can See where bases joins

Principles of disease (47 decks)

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