Module 8 - Part 1

Question 1

Aneuploidy

Answer 1

Abnormal chromosome number
- Chr # not an exact multiple of haploid #

Question 2

Types of aneuploidy

Answer 2

1. monosomy (2n-1) missing 1 chr of a pair (45)
2. nullisomy (2n-2) missing a pair of homologous chr (44)
3. trisomy (2n+1) an extra chr (47)
4. tetrasomy (2n+2) an extra pair of chromosomes (48)

Question 3

Trisomy 21

Answer 3

Most prevalent viable aneuploidy (0.15% of all live births)
- down syndrome
- common traits: heart defects/hearing deficits, etc.
- has considerable phenotypic variation

Question 4

Trisomy 18 & 13

Answer 4

Die shortly after birth
- Edwards & patau syndrome

Question 5

Maternal age = 20
Risk of DS & any chromosomal abnormalities

Answer 5

DS: 1/1667
Any: 1/526

Question 6

Maternal age = 30
Risk of DS & any chromosomal abnormalities

Answer 6

DS: 1/952
Any: 1/385

Question 7

Maternal age = 35
Risk of DS & any chromosomal abnormalities

Answer 7

DS: 1/378
Any: 1/192

Question 8

Meiosis

Answer 8

• type of cell division in GERM cells
• single cell divides to produce FOUR NON-IDENTICAL daughter cells
• each has 1/2 as many chromosomes

Question 9

Meiosis II

Answer 9

• cell division without DNA duplication
• production of haploid gamete

Question 10

Meiosis I

Answer 10

• crossing over
• exchange of gen material b/w NON-SISTER CHROMATIDS of homologous chromosome
• non-identical DNA

Question 11

Disjunction

Answer 11

• seperation & segregation of chromosomes to two daughter cells (meiosis I)
• pulling apart of sister chromatids (meiosis II)

Question 12

Non-disjunction

Answer 12

when separation & segregation DO NOT OCCUR
- aneuploidy