X and Y Chromosomes, and Genetic Diagrams
- Created by: Davwi
- Created on: 11-03-19 20:50
Fullscreen
X and Y chromosomes
- There are 23 pairs of chromosomes in every human body cell. Of these, 22 are matched pairs of chromosomes that only control charcteristics. The 23rd pair are labelled ** or XY. They're the two chromosomes that decide your sex- whether you turn out male or female.
- Males have an X and a Y chromosome: XY (the Y chromosome causes male characteristics).
- Females have 2 X chromosomes: ** (the ** combination allows female characteristics to develop).
- When making sperm, the X and Y chromosomes are drawn apart in the first division of meiosis. There's a 50% chance that eac sperm cell gets an X chromosome and a 50% chance each chromosome gets a Y chromosome.
- A similar thing happens when making eggs, but original cell has 2 X chromosomes so all the eggs have one X chromosome.
Genetic diagrams
- To find the probability of getting a boy or a girl, you can draw a genetic diagram.
- Genetic diagrams are just models that are used to show all the possible genetic outcomes when you cross together different genes or chromosomes.
- Put all the possible gametes from one parent down one side, and those from the other parent along the top.
- Then in each middle square fill in the letters from the top and side that…
Comments
No comments have yet been made