X and Y Chromosomes Flashcards
What do your chromosomes control?
Whether you are a boy or girl.
How many chromosomes in every human body cell?
22 matched pairs of chromosomes.
What are the 23rd pair labelled?
XX or XY.
The 2 chromosomes that decide whether you are a girl or boy.
What do all men have?
An X and a Y chromosome.
The Y causes male characteristics.
What do all women have?
Two X chromosomes.
The XX combination allows female characteristics to develop.
What happens when making sperm?
The X and Y chromosomes are drawn apart in the first division in meiosis.
50% chance each sperm cell gets an X-chromosome and a 50% chance it gets a Y chromosome.
What happens when making egg?
Similar process to making sperm.
But the original cell has 2 X chromosomes so all the eggs have one X- chromosome.
What do genetic diagrams show?
The possible combinations of gametes.
