Crossing Over and Non-Disjunction

Question 1

What are autosomes?

Answer 1

Chromosomes not involved w/ sex determination
22 of the chromosomes from mum or dad (not sex chromosomes - the last pair)

Question 2

What is a Karyotype?

Answer 2

Pictures of chromosomes arranged in homologous pairs (one from mum and from dad)

Question 3

What is Independent assortment?

Answer 3

When during Metaphase I, chromosomes are arranged in homologous pairs along the equator of the cell, paternal chromosomes will move in opposite directions to allow for exchange of genetic info
This way, the resulting gametes
have diff. combinations of
paternal chromosomes

Question 4

What is Crossing Over?

Answer 4

When Homologous chromosomes/Non-Sister chromatids exchange pieces of chromosome when they are lined up during Prophase I
The results is chromosomes with
genes of paternal and maternal
origin

Question 5

What is Non-Disjunction?

Answer 5

It’s when two homologous chromosomes move to the same pole during meiosis
The result is that one of the daughter cells will be missing one chromosomes and the other will have an extra one
It can occur in Anaphase I & II
I
Homologous Chromatids pairs
do not separate to opposite
poles
II
Sister chromatids are pulled
together towards the same pole

Question 6

What is Monosomy?

Answer 6

When a chromosome is missing
Turner syndrome: missing X chromosome, underdev. female sexual characteristics

Question 7

What is Trisomy?

Answer 7

When an extra chromosome is gained
Trisomy 21: Down Syndrome
Impairment of growth, lower cognitive ability