Friday may 7th, 2010

In humans, there are 23 pairs of chromosomes, 2 of them determine the sex of the human, “X”, and “Y”. The X chromosome is bigger than Y; the combination of these two will give birth to a boy or girl.
XX= Female
XY= Male

The sperm possessed both X and Y chromosome, while the ovum only the X one, you cannot say that the Male determine the sex of the kid, although it has both X and Y, he cannot control whose going to combine with the other X chromosome, there are some experimental test, which involve “training” of the sperm, so you could manipulate and determine the sex.

(It’s impossible to combine a YY chromosome, because the ovum only possess the X)

Co-Dominance

It is when both alleles are “Dominant”, and both characteristics are shown on. For example:

Blood type.
A is Dominant, B is Dominant, but O is recessive, when A and B combine, you have a AB blood type, but if you combine A or B with O, then you won’t have an O blood type, since is recessive, you need to combine both O, so you get a O blood type:

	A	B
A	AA	AB
O	AO	BO

A woman (AB), marries a man with (A; Heterozygous), what is the chance of the baby to have O blood type?

Answer: None, there is a chance of having A: 50%, B: 25% and AB: 25%

A always win over O
B always win over O
A always share over B
O need another O

AB= Universal Receptor; Since it has A and B blood type, you can add A or B blood, and the body will accept this blood since it has information about both types.

O= Universal Donor; O blood type doesn't have any antibodies on the blood, so you can give this blood to A, B and AB, but it isn't always sure, there is still a slim chance of an allergic reaction to this blood type, so it's save as last resort.

Xavier Gomez