Chromosome abnormalities Flashcards Preview

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Flashcards in Chromosome abnormalities Deck (38):
1

What are three different forms of chromosome abnormalities

Numerical
Structural
mutational

2

What is the most common numerical chromosome

Trisomy (extra chromosome)

3

What is a chromosomal monosomy abnormality and an example

One less chromosome
eg Turners 45x

4

Where does most numerical abnormalities occur

Non disjunction in meiosis
and Unbalanced Robertsonian translocation

5

What is caused by a trisomy of 21

Down syndrome

6

What is Patau syndrome

47 + 13
Mental retardation

7

What is Edwards syndrome

47 + 18
development problems

8

What is sex linked numerical abnormalities and what genders display them

Males - Kinefelter syndrome 47 XXY
Females - Turner syndrome 45 X
both cause infertility

9

What can structural abnormalities be due to

Transloction
Deletions
Insertions
Inversions

10

What are the different translocations

Reciprocal either balanced or unbalanced
Robertsonian

11

What is the difference between balanced and unbalanced rearrangement

Unbalanced rearrangment results in partial trisomy
as there is an unequal copy of information between the two new derivatives formed

12

What is reciprocal translocation and where would this most likely occur in cell division

involving breaks in two chromosomes with formation of two new derivative chromosomes
chiasma at metaphase

13

How can unbalanced translation occur

If normal chromosome parent combine with chromosome of parent 2 with balanced translocation

14

What happens in Robertsonian

fusion of two acrocentric - where the centromere is located quite near one end - chromosomes resulting in two combined chromosomes

15

How does robertsonian translocation cause trisomy and monosomy

As the fused acrocentric chromosome means there is either extra or less chromosome material passed on from unbalanced gametes to form trisomy/monosmy zygotes

16

What are the two forms of inversion and whats the difference

paracentric inversion -
pericentric inversion - involves centromere

17

What are the five acrocentric chromosomes

13 14 15 20 21

18

What happens in deletion

there is a break in the chromosome

19

What can a genetic mutation either be

somatic or germline

20

Define polymorphism

Change in genotype but to phenotypic effect

21

What are four types of coding mutations

silent - Base change but codes for same amino acid
missense - base changes and codes for new amino acid
nonsense - base change causes a stop to process i.e. codon prevent amino acid being formed
frameshift - either deletion or insertion of a base

22

What is point mutation of base pair of a purine to purine called

Transition

23

What is a point mutation of a Purine to pyrimidine called

Transversion

24

What are five methods of detecting mutations

Polymerase chain reaction (PCR)
Gel electrophoresis
Restriction fragment length polymorphism (RFLP) analysis
Amplification refractory mutation system (ARMS)
DNA sequencing

25

What is needed for PCR

DNA polymerase
DNA
Nucleotides

26

What are the steps of PCR

1. Denature (high temp)
2. Anneal (low temp)
3. extend (70-75 temp)
4. Gel electrophoresis

27

What does Gel electrophoresis do

Separate DNA fragments by size

28

What is the movement of DNA in Gel electrophoresis

DNA negatively charged, applying an electric field moves to positive charge

29

What is the advantages of PCR and Gel electrophoresis

Speed
Ease of use
Sensitive
Robust

30

How is ARMs applied

PCR reaction using fluorescent primer either wild type or mutant to see if mutation present, if present with mutant primer causes amplification

31

What is Restriction endonucleases

Enzymes from bacterial cells that cleave DNA

32

What does RFLP use (restriction fragment length polymorphism)

Restriction endonuclease cutting PCR DNA,

33

How do we know it mutant present using RFLP

If mutant fragment present will show up on restriction digest assay

34

What can RFLP used to diagnose?

sickle cell anaemia

35

In DNA sequencing what is a chain terminated by

dideoxynucleotides

36

How do dideoxynucleotides terminate a DNA sequence

DNA polymerase cant recognise them so chain is stopped

37

What is the least suitable method for detecting whether an individual is a carrier of sickle cell anaemia

Karyotyping

38

Why cant a karyotype show a point mutation

as shows whole chromosome