So, say I get a set of chromosomes from my Mum which contains the X chromosome and the same from my Dad, but with the Y chromosome. I now have two sets of the same 22 chromosomes, plus an X and a Y.
For chromosome number one for example, is everything from my Dad’s side activated? My Mum’s? Or is is a random selection of genes within each chromosome?
And does the X chromosome do anything for me, or is it turned off, and only used if I pass it on to the next generation?
Follow up question: I believe that women actually recombine their X chromosomes when passing these on, but men can’t recombine X and Y. So everything on your Dad’s side stays the same. Does this have any impact? For example are you more likely to inherit genetic defects from your Dad’s side?
Some genes are lethal let’s call them :
“T” bad version and
“t” for the version that lets you live.
if one of those genes is on the xx // xy chromosomes then if you are XX female you will get one combination in this set of combinations : Tt, tT, TT, tt
if you get TT, you are dead.
if you get tt, you live,
if you get Tt or tT you have 3 possible outcomes :
if T is dominant you are dead,
if t is dominant you live,
if T and t are co_dominant you might be sick.
if you are XY male, you have either a “T” (dead) or a “t” (alive).
I didn’t realize I have the same question as OP, and I don’t think you answered it. The question is: how do the gene selections happen? What process decides?
Not every combination is being tried in the egg during fertilization, right? You describe the outcome, but not how the gene combination selection process happens, and what decides which genes are used.
You might absolutely be right about the meaning of O.P.s’ (confused) question. But still i hope at least i answered o.k. from this part :
P.S. : You asked :
Gene selection is made before the synthesis of the gametes : for instance a male having XY will produce sperms, each one with either an X or with a Y.