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Flashcards in Mutations and Genetic Analysis Deck (30):
1

What are the 3 types of chromosomal abnormalities?

-numerical
-structural
-mutational

2

What happens to most foetuses which have chromosomal abnormalities?

first trimester miscarriage

3

What type of chromosomal abnormality accounts for 50% of first trimester miscarriages?

Trisomy

4

Name a monosomy syndrome?

Turner syndrome, 45 X

5

What are 3 trisomy syndromes?

-Patau 47,XX+13
-Edwards 47,XY+18
-Down 47,XX+21

6

What is the chromosome complement of Klinefelter Syndrome?

47,XXY

7

Where do most cases of non-disjunction originate?

In the mother

8

What are the characteristic of Down's Syndrome?

-characteristic facial dysmorphologies
-IQ less than 50
-Average life expectancy 50-60 years
-Alzheimer's disease in later life
-Usually a result of maternal non-disjunction (also unbalanced Robertsonian translocation and Mosaicism)

9

What are the characteristic of Patau Syndrome?

-multiple dysmorphic features and mental retardation
-Very few survive beyond first year
-usually a result of maternal non-disjunction (also unbalanced Robersonian translocation)

10

What are the characteristics of Edwards Syndrome?

-severe developmental problems; most patients die within first year
-usually caused by maternal non-disjunction

11

What are 2 examples of sex chromosome aneuploidy syndromes?

-Turner Syndrome
-Klinefelter Syndrome

12

What are the characteristics of Turner Syndrome?

-mainly result in miscarriage
-females of short stature and infertile
-neck webbing and widely spaced nipples
-intelligence and lifespan is normal

13

What are the characteristics of Klinefelter syndrome?

-tall stature, long limbs
-male but infertile, small tested, about 50% gynaecomastia
-mild learning difficulties

14

What does structural abnormalities include?

-balanced or unbalanced rearrangements
-translocations
-deletions
-insertions
-inversions

15

What are the 2 kinds of translocation?

-Reciprocal: involving breaks in 2 chromosomes with formation of 2 new derivative chromosomes
-Robersonian: fusion of two acrocentric chromosomes

16

What types of mutation are there?

-non-coding
-coding which can be silent, missense, nonsense, frameshift (deletion/insertion)

17

What point mutations exist?

-transitions
-transversions

18

What is a transition mutation?

- A mutation which changes a purine nucleotide to another purine nucleotide A>G
OR
A mutation which changes a pyrimidine nucleotide to another pyrimidine nucleotide C>T

19

What is a transversion mutations?

A substation of purine for a pyrimidine A>C
OR
A substitution of pyrimidine for a purine C>G

20

How can mutations be detected?

-polymerase chain reaction (PCR)
-gel electrophoresis
-restriction fragment length polymorphism (RFLP) analysis
-amplification refractory mutation system (ARMS)
-DNA sequencing

21

What is needed for PCR?

-sequence information
-oglionucleotide
-DNA
-nucleotides
-DNA polymerase

22

What 3 steps are repeated in PCR?

-denature
-anneal
-extend

23

Describe gel electrophoresis.

-separate DNA fragments
-apply an electrical field
-DNA is negatively charged
-separate through agarose gel matrix
-visualise DNA fragments

24

What are the advantages of gel electrophoresis?

-speed
-ease of use
-sensitive
-robust

25

What can PCR be used for?

-DNA cloning
-DNA sequencing
-In vitro mutagenesis
-gene identification
-gene expression studies
-forensic medicine
-typing genetic markers
-detection of mutations

26

What are the advantages/disadvantages of ARMS?

-Advantages= cheap, labelling not required
-Disadvantages= electrophoresis required, primer design critical, need sequence information, limited amplification size, limited amounts of product, infidelity of DNA replication

27

What are restriction endonucleases?

-enzymes from bacterial cells that provide a protective mechanism by degrading DNA of invading viruses.
-they recognise specific DNA sequences, usually 4-8 bp long and always cut DNA at the same site

28

What are the advantages/disadvantages of RFLP?

-advantages= simple, cheap, non-radioactive
-disadvantages= requires gel electrophoresis, not always feasible

29

How can DNA be sequenced?

-chain termination method
-use of dideoxynucleotides

30

What are the advantages/ limitations of DNA sequencing by Sanger?

-advantages= mutation detection, automation and high throughput, next generation sequencing
limitations= expensive equipment, poor quality sequence read