Lecture 3 Flashcards
1
A
- Study of the structure and function of a chromosome
- Used for the screening and dianosis of inherited chromosomal disorders
2
Q
Karyotype
A
Chromosomes arranged in size order
3
Q
Karyotype process
A
- 10-30ml blood sample, add drops to culture flasks containing growth medium and add phytohemaggultin to stimulate mitosis
- Incubate for 3 days
- Treat with Colcemid to stop mitosis in metaphase and transfer cells to tube
- Pellet cells by centrifugation, add hypotonic solution to lyse cells
- Drop cells on microscope plate with Giesma stain and take photos
4
Q
How do we identify chromosomes?
A
- Banding pattern
- Size
- Placement of centromere (metacentric, submetacentric or acrocentric)
5
Q
Polyploidy
A
- Extra whole sets of chromosomes
- Rare in animals but common in plants
6
Q
Aneuploidy
A
additional or missing chromosomes
7
Q
Monosomy
A
Missing chromosomes
Non-disjunction in meisosis 1
8
Q
Trisomy
A
Additional chromosomes
Non-disjunction in meiosis ll
9
Q
Down’s syndrome
A
- Trisomy of 21
- Chances increase with maternal age
10
Q
Screening for chromosome abnormalities
A
- Amniocentesis and karyotyping
- Blood tests to detect proteins from Down’s
- Ultrasound scans
11
Q
Turner’s syndrome
A
- 45 X0
- Only viable human monsomy
- 1 X chromosome
- Phenotypically female but sterile
- Oestrogen replacement therapy
12
Q
Klienefelter’s syndrome
A
- 47 XXY
- Phenotypically male with some female features
- Tall, sterile
- Hormone replacement therapy
13
Q
Cri-du-chat
A
- Deletion in chromosome 5
- 1 in 50,000 live births
- Defects in glottis and larynx
- Wide face with saddlenose
- Physical and mental impairment
14
Q
Prader-willi syndrome
A
- Deletion in chromosome 15 from paternal
- poor suckling reflex
- Uncontrollable eating
- Obesity, sexual impairment
- Diabetes
15
Q
Angelman syndrome
A
- Defection in chromosome 15, maternal
- happy demeanor, laughter
- Physical and mental impairment
- Speech problems
