kenny1999 Posted February 22 Share Posted February 22 It's said that we share a little bit more DNA with our mother, compared to our father. Does it also mean that we also share a little bit more DNA with cousins from our mother side, compared to our father side? Link to comment Share on other sites More sharing options...
TheVat Posted February 22 Share Posted February 22 Yes, you share mitochondrial DNA with all those in the maternal lineage, since mitochondria in the egg are preserved but sperm mitochondria are destroyed during fertilization. That mitochondrial DNA tips the balance towards the mother in terms of total DNA. If you are male, you also got a little more nuclear DNA from mom anyway, since the Y chromosome is much shorter than the X. (which is why a recessive gene on the X chromosome, like one for color blindness, will be more likely to be expressed in male children - the Y chromosome lacks most of the genes that are on the X. Link to comment Share on other sites More sharing options...
Genady Posted February 22 Share Posted February 22 58 minutes ago, TheVat said: If you are male, you also got a little more nuclear DNA from mom anyway, since the Y chromosome is much shorter than the X. OTOH, if you are male, you have X and Y chromosomes, while if you are female, you have only one X, since the other X gets inactivated (see Barr body). 1 Link to comment Share on other sites More sharing options...
TheVat Posted February 22 Share Posted February 22 4 hours ago, Genady said: OTOH, if you are male, you have X and Y chromosomes, while if you are female, you have only one X, since the other X gets inactivated (see Barr body). Yes, good point... in terms of gene transcription, mammals seek to equalize the gene expression between the sexes by silencing one X chromosome. An excess of gene product from two active Xs would not be good. If both X chromosomes are active, as in the case of a pathological reactivation of Barr bodies, that can be a sign of breast cancer. I guess one could say males have slightly more gene product, due to active code pertaining to gonadal development on the Y, while females have a bit more total code, but only more gene product when there is pathology, like cancer. The equalization of gene expression is called dosage compensation and is an area of genetics that gets fairly complicated. We just scratched the surface in my biology courses. 1 Link to comment Share on other sites More sharing options...
Genady Posted February 22 Share Posted February 22 24 minutes ago, TheVat said: We just scratched the surface in my biology courses. We too, just touched it. Link to comment Share on other sites More sharing options...
kenny1999 Posted February 28 Author Share Posted February 28 Hi all. Is the answer to my question positive? i.e. A little bit more for the cousins on the mother side? Link to comment Share on other sites More sharing options...
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