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Wing Genealogist
07-17-2016, 05:40 PM
How does the X-Chromosome recombine? I know males inherit only a single X-Chromosome and females inherit a pair of X-Chromosomes. However, is the daughter's X-Chromosomes recombined between her father's and mother's X-Chromosomes or do they represent one complete Chromosome from her father and one complete Chromosome from her mother. In addition, does a son receive a combination of his mother's two X-Chromosomes, or does he only receive one complete X-Chromosome from his mother.

I believe I may know the answers, but I want to verify with others.

vettor
07-17-2016, 06:17 PM
Logically

If a male receives the complete Y from his father , then logically when he received an X from his mother then it would be a complete one.................but which X of the 2 from his mother ...........is this what you are seeking ?


The phasing I have done via my father and sons for the Y ..............has never been 100% perfect , always 1 % is mixed ( unless the phasing programs are in error )

vettor
07-17-2016, 06:36 PM
Maybe you should start from the time of conception

ALL humans are conceived as "females" with only one X each .................logically it should be identical , be it if one ends up Male or stays Female.
After about 6 to 9 weeks the Y starts ( if you have the Y ) and you become Male .....or the other X starts and you stay Female

So , the first X is what you need to seek

Wing Genealogist
07-17-2016, 07:28 PM
vettor: What I am asking is whether the X-Chromosome a man receives from his mother is entirely from one of her X-Chromosomes (and entirely excludes the other X-Chromosome) or whether their was some recombination between these two X-Chromosomes to create the X-Chromosome for the child.

I believe the latter is what happens, and the boy's X-Chromosome is a mixture of his mom's two X-Chromosomes.

Saetro
07-17-2016, 07:50 PM
vettor: What I am asking is whether the X-Chromosome a man receives from his mother is entirely from one of her X-Chromosomes (and entirely excludes the other X-Chromosome) or whether their was some recombination between these two X-Chromosomes to create the X-Chromosome for the child.

I believe the latter is what happens, and the boy's X-Chromosome is a mixture of his mom's two X-Chromosomes.

A pair of X chromosomes is like any other pair (of chromosomes 1-22).
https://wikispaces.psu.edu/display/110Master/Chromosome+Behavior+and+Sex+Chromosomes
So yes, they cross over.

The difference is with a male parent (XY) who effectively has nothing to crossover with, and hands on his X chromosome unchanged.
The GEDmatch Tier 1 predictive inheritance tool I mentioned elsewhere recently makes this plain.

Or the descriptions of X inheritance at Blaine Bettinger's blog http://thegeneticgenealogist.com/2013/03/22/looking-for-my-x-dna-charts/

Wing Genealogist
07-17-2016, 09:40 PM
I see where my "assumption" about X-Chromosome inheritance of a daughter was incorrect. I had believed the X-Chromosome from the mother (egg) and the X-Chromosome from the father (sperm) would recombine in the daughter, but it does not. One X-Chromosome of the daughter is an exact copy from her father's X-Chromosome. The other X-Chromosome in a daughter is a "combined" copy from her mother's two X-Chromosomes (which did go through the process of recombination).

For a male, the child simply receives one X-Chromosome from his mother, and this X-Chromosome is a recombination of the mother's two X-Chromosome.

Useful to know, as I am exploring the using X-Chromosome testing to see if it is possible to deduce at least some X-Chromosome regions of Mayflower passengers. (see http://www.anthrogenica.com/showthread.php?7904-Autosomal-DNA-for-Mayflower-Wiki)

vettor
07-18-2016, 06:11 AM
I see where my "assumption" about X-Chromosome inheritance of a daughter was incorrect. I had believed the X-Chromosome from the mother (egg) and the X-Chromosome from the father (sperm) would recombine in the daughter, but it does not. One X-Chromosome of the daughter is an exact copy from her father's X-Chromosome. The other X-Chromosome in a daughter is a "combined" copy from her mother's two X-Chromosomes (which did go through the process of recombination).

For a male, the child simply receives one X-Chromosome from his mother, and this X-Chromosome is a recombination of the mother's two X-Chromosome.

Useful to know, as I am exploring the using X-Chromosome testing to see if it is possible to deduce at least some X-Chromosome regions of Mayflower passengers. (see http://www.anthrogenica.com/showthread.php?7904-Autosomal-DNA-for-Mayflower-Wiki)

I do not see what you are trying to say................maybe the link below will help you

http://freepages.misc.rootsweb.ancestry.com/~bonsteinandgilpin/x-ch.htm

Wing Genealogist
07-18-2016, 10:09 AM
Vettor: I believe we are looking at opposite sides of the same proverbial coin. The links you are providing show how X-DNA is inherited across a number of generations (and only certain ancestors have the possibility of passing on some of their X-Chromosome).

I am looking at the specific parent-child inheritance and whether the X-Chromosome is recombined between the egg & sperm. One of the links you posted in #3 had a link to a site which stated (in a different manner) that their is no recombination of the X-Chromosome between the egg & sperm. If this site was incorrect (and their is recombination of the X-Chromosome between the egg & sperm) then it would have repercussions in terms of what I am looking into (if X-Chromosome testing of living individuals can be used to identify X-Chromosome segments of Mayflower passengers).

vettor
07-18-2016, 06:51 PM
Vettor: I believe we are looking at opposite sides of the same proverbial coin. The links you are providing show how X-DNA is inherited across a number of generations (and only certain ancestors have the possibility of passing on some of their X-Chromosome).

I am looking at the specific parent-child inheritance and whether the X-Chromosome is recombined between the egg & sperm. One of the links you posted in #3 had a link to a site which stated (in a different manner) that their is no recombination of the X-Chromosome between the egg & sperm. If this site was incorrect (and their is recombination of the X-Chromosome between the egg & sperm) then it would have repercussions in terms of what I am looking into (if X-Chromosome testing of living individuals can be used to identify X-Chromosome segments of Mayflower passengers).

I am saying, that since we are all taught that your Y comes from your father, from his father, from his father etc..........and the X comes from your mother , her mother, her mother etc............then clearly the theory you propose that the X comes from your paternal line is in error.

The male Y of the sperm mixes with the female X to form a boy
if the male X of the sperm is successful then that mixes with the female X to form a girl ................the males sperm only part is deciding if you get a boy or girl. The female egg makes up the bulk of the X-CHR
The human Y chromosome is unable to recombine with the X chromosome, except for small pieces of pseudoautosomal regions at the telomeres (which comprise about 5% of the chromosome's length). The bulk of the Y chromosome which does not recombine is called the "NRY" or nonrecombining region of the Y chromosome.

https://en.wikipedia.org/wiki/Pseudoautosomal_region

geebee
07-18-2016, 09:09 PM
Wing, recombination doesn't occur during fertilization. It occurs earlier than that, in the germ cells of each parent.

Recombination is part of a process called meiosis, which only happens in the formation of the sex cells. So by the time you get to egg and sperm, each only contains one X. In the case of the egg, it may be a recombination of the two X chromosomes of the mother, containing DNA from each. Or, it may contain only DNA from either her father or her mother.

Obviously, the X chromosome in the sperm will only contain DNA from the man's mother -- with the possible exception of a couple of regions designated as PAR1 and PAR2. These two regions, one at each end of the X and Y chromosomes, can actually recombine. However, the SNPs in these regions aren't reported as part of the Y, but as part of the X. What's reported as the Y is actually slightly truncated, and doesn't include SNPs from a recombining region.

Anyway, once fertilization takes place, cell division is by mitosis. That is, the chromosomes are simply duplicated within the cell, then the cell divides. Each of the two cells now contains a full complement of chromosomes. The only exception to this is in the germ cells of the new organism, where meiosis can result in new recombinations of each pair of chromosomes. Of course, we won't see those recombinations at work until the next generation.