Chromosome Abnormalities/Mutations/Analysis Flashcards Preview

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Flashcards in Chromosome Abnormalities/Mutations/Analysis Deck (29)
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1

Give the three main types of chromosome abnormalities

Numerical
Structural
Mutational

2

Give types of numerical chromosome abnormalities

Non-disjunction
Autosomal aneuploidy
Sex linked aneuploidy

3

Describe the mechanism of non-disjunction

Problem in meiosis to give a disomy (two copies of a chromosome in a daughter cell/gamete)

4

What does non-disjunction give rise to in offspring?

Trisomy (an extra chromosome in a cell)

5

What is caused by trisomy in chromosome 21?

Down syndrome

6

Trisomy in chromosome 13?

Patau syndrome

7

Chromosome 18?

Edwards syndrome

8

Chromosome 45,X?

Turner syndrome

9

Chromosome 47,XXY?

Klinefelter syndrome

10

Give some features of Patau syndrome

- dysmorphic features
- mental retardation

11

Features of Edwards syndrome?

- developmental problems

12

Features of Turner syndrome?

- female
- short stature
- neck webbing
- widely spaced nipples

13

Features of Klinefelter syndrome?

- male
- infertile
- small testes
- tall
- long limbs

14

Give types of structural chromosome abnormalities

Balanced/unbalanced reciprocal translocation

Robertsonian translocation

Inversion

Deletion

Insertion

15

What is reciprocal translocation?

Chromosome breaks in two and forms two new derivatives

Balanced - same amount of each at the end; phenotypically normal

Unbalanced - from normal parent and another with balanced translocation; gives rise to trisomy/monosomy in offspring

16

What is Robertsonian translocation?

Occurs in acrocentric chromosomes;

- long arms (q) attach to long arms
- short arms (p) attach to short arms

Gives rise to abnormalities in offspring if they receive unequal amounts of a chromosome

17

Give two types of inversion

Paracentric inversion - abnormal fixing, no centromere involvement

Pericentric inversion - abnormal fixing in the centromere region

18

Give the four types of mutational coding abnormalities

Silent
Missense
Nonsense
Frame shift

19

What is the difference between transitions and transversions?

Transitions - purine mutates to purine, pyrimidine mutates to pyrimidine

Transversions - purine mutates to pyrimidine, pyrimidine mutates to purine

20

Give types of mutational chromosome abnormalities

Germline/somatic
Gene disruption
Polymorphism

*All may be coding/non-coding/point mutations

21

Give the main types of abnormality detection

PCR
ARMS
RFLP
DNA sequencing

22

What is PCR?

Polymerase chain reaction

23

What happens during PCR?

- denaturation to create a single-stranded DNA
- annealing (bonding of primers to DNA template
- extension of primers using DNA polymerase to synthesise new DNA strands behind them
- repetition to amplify target DNA
- analysis using gel electrophoresis

24

What is ARMS?

Amplification refractory mutation system

25

What happens during ARMS?

- sequence specific primers will only amplify if the target allele is present

- wild type allele amplified by a normal primer
- mutant allele amplified by a mutant amplification

- then undergoes PCR and gel electrophoresis

26

What is RFLP?

Restriction fragment length polymorphism

27

What happens during RFLP?

- restriction enzyme cuts DNA strand at different lengths

- gel electrophoresis

28

What is DNA sequencing?

the process of determining the precise order of nucleotides within a DNA molecule

29

How does DNA sequencing work?

- double helix denatured
- one strand isolated
- radioactively labelled primer used to replicate strand
- primer elongates to match strand and reform a double strand (stops at ddNTP)
- gel electrophoresis (coloured dye shows up)