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1.Do women inherit the genes for diseases like breast cancer only from the genes of their mother or also from their father's genes?

2. Are the genes on the Y chromosome the only ones that determine that you will become a boy?

3. Are the two X chromosomes in females different? Does only one determine that you will become a girl? And is the one X chromosome that males have the same as the one females have?

Thank you
Question Date: 2004-12-07
Answer 1:

1. A number of genes associated with breast cancer have been found. So far, all these genes are found on non-sex, or somatic chromosomes. This means that women can inherit them from either their mother or father.

2. Yes, to become a boy you must inherit a Y chromosome from your father. Occasionally, children are conceived with one X and no other sex chromosomes, they develop as sterile females, with some other abnormalities (this condition is called Turners syndrome). The Y chromosome is very tiny and carries very few genes. The genes it does carry are mainly regulatory, that is, they instruct control how other genes located on the somatic chromosomes behave. So not all the genes that contribute to male traits like facial hair, taller height, etc., are on the Y chromosome, but the genes that control those genes are.

3. The 2 X chromosomes are different since females inherit one from their mother and the other from their father. They carry all the same genes that code for the same traits, but may have different alleles of those genes, that is, the traits on each chromosome may be slightly different (like brown vs. blue eye color). As mentioned above, you only need one X chromosome to become a female, but you need two X chromosomes to become a normal female. During development, both X chromosomes are being transcribed in the embryo. However, at a very early stage, one X chromosome in each cell condenses into a tiny mass and becomes non-functional. The other X chromosome continues functioning. It is completely random which of the X chromosomes condenses.

Answer 2:

I think from both. It would depend on which chromosome those genes are.

The chromosome from your father is the one that will determine if you are a boy or girl. You will always get an X from your mother because she has X and X. Your father has an X and a Y. If you get an X from him, you will be a girl because you have XX, if you get a Y from him you will be a boy because you have XY.

So, yes, the X that males have is the same as the X females have, and the two X chromosomes code for the same things.

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