Chromosomes and Abnormalities Flashcards

1
Q

How many pairs of chromosomes?

A

46 chromosomes
22 autosomal pairs
1 pair of sex chromosomes XX or XY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What cell types can be cultured to test for cytogenetics?

A
  • Blood – T-lymphocytes
  • Skin / Umbilical cord / Placenta
  • Bone marrow
  • Solid tumour
  • Amniotic fluid / Chorionic villus - Prenatal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How are cell samples put into the process of karyotyping?

A
  1. Place sample in culture medium containing PHA
  2. Incubate for 48-72 hours
  3. Add colcemid - inhibits spindle formation, stops cells at metaphase to see condensed chromosomes
  4. Add hypotonic solution - cells swell
  5. Cells dropped and fixed onto slide to spread
  6. Slides are then treated with trypsin to digest proteins and giemsa to produce g banding on chromosomes
  7. Slides are scanned, analysed in software.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How are the regions numbered on chromomes?

A

Regions increase from centromere outwards.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the ISCN for a normal female and normal male?

A

46,XX
46,XY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Two types of chromosomes abnormalities:

A

Numerical, structural

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Two types of chromosomes abnormalities:

A

Numerical, structural

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name 3 numerical chromosome abnormalities with ISCN:

A

Trisomy - Extra chromosomes at 21, Downs syndrome
47,XX,+21
Monosomy - Loss of a chromosome, Turner syndrome
45, X
Polyploidy - 3 whole sets of chromosomes, 69 XXY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Name the 4 structural chromosome abnormalities with ISCN:

A

Translocation - Exchange of material
Inversion - Changing of orientation, no loss or gain of material
Duplication - Gain of material
Deletion - Loss of material
ISCN ?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is non disjunction and where does it occur?

A

When the chromosome doesn’t separate properly in meiosis.
Occurs in meiosis 1 and meiosis 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does non disjunction affect meiosis 1?

A

Results in - 2 disomic gametes + 2 nullisomic gametes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does non disjunction affect meiosis 2?

A

Results in - 1 disomic gametes,
1 nullisomic gametes,
2 normal gametes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does disomic gamete and nullisomic gamete affect conceptus?

A

Disomic - Leads to trisomy
Nullisomic - Leads to monosomy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Edwards syndrome karyotype?

A

47,XX,+18

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Patau syndrome karyotype:

A

47,XX,+13

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is triploid karyotype?

A

3 copies of each chromosome,
Can cause …

16
Q

What is reciprocal translocation?

A

A balanced exchange of chromosomal material

17
Q

What is Robertsonian translation?

A

Centromere is at the top of the chromosome, if joined by centromere would create a new chromosome.

18
Q

What is unbalanced rearrangement?

A

A deletion of part of chromosome eg p arm of 5 chromosome