Meiosis and Chromosome Abnormalities

Question 1

process of Meiosis

Answer 1

Prophase I
Metaphase I
Anaphase I
Telophase I

Prophase II
Metaphase II
Anaphase II
Telophase II

Question 2

Spermatogenesis

Answer 2

commences in puberty

four sperm cells are formed per meiotic cycle

over a course of 60 days

undergo more divisions than eggs, meaning more chances of mutations

Question 3

oogenesis

Answer 3

occurs in early embryonic life

each meiotic cycle produces one ovum and 3 polar bodies

process occurs over 10-50 years

polar bodies mature into ova

Question 4

trisomy 21

Answer 4

down’s syndrome

non-disjunction

chances increase with advancing maternal age

distinct facial characteristic

IQ less than 50

Question 5

Trisomy 14

Answer 5

patau syndrome

usually caused by non-disjunction

multiple dysmorphic features

very few survive beyond first year

Question 6

Trisomy 18

Answer 6

Edwards syndrome

non-disjunction

most die within first year of life

Question 7

X-Turner sundrome

Answer 7

short stature and infertile

neck webbing and widely spaced nipples

normal intelligence and lifespan

97% zygotes terminate at conception

Question 8

XXY klinefelter syndrome

Answer 8

tall stature and long limbs

infertile, small testes

50% develop breasts

mild learning difficulties

Question 9

Types of structural chromosome anomalies

Answer 9

Robertsonian translocation - occurs in acrocentric chromosomes, one long armed and one short armed chromosome

deletions - section of chromosome disappears from one or both arms

inversions:
paracentic - when a section of DNA in the arm of the chromosome is inverted
Pericentric - when the DNA around the centromere of the chromosome is inverted