"Steve Hayes" <hayesmstw@hotmail.com> wrote in message news:u83iq3d8vfgnddl8566tsd9hug2ihju95m@4ax.com... > If this goes any further, we may need genealogy software that allows one to > enter three or more parents - and what would a pedigree chart look like then? > > http://news.yahoo.com/s/ap/20080205/ap_on_sc/embryo_research > > LONDON - British scientists say they have created human embryos containing DNA > from two women and a man in a procedure that researchers hope might be used > one day to produce embryos free of inherited diseases. > ... Very good question. However, this can also be called genetic engineering and thus there may be NO parents! I think you're getting ahead of us. How much of a DNA contribution is worthy of note?

D. Stussy wrote: > "Steve Hayes" <hayesmstw@hotmail.com> wrote in message > news:u83iq3d8vfgnddl8566tsd9hug2ihju95m@4ax.com... >> If this goes any further, we may need genealogy software that allows one > to >> enter three or more parents - and what would a pedigree chart look like > then? >> http://news.yahoo.com/s/ap/20080205/ap_on_sc/embryo_research >> >> LONDON - British scientists say they have created human embryos containing > DNA >> from two women and a man in a procedure that researchers hope might be > used >> one day to produce embryos free of inherited diseases. >> ... > > Very good question. However, this can also be called genetic engineering > and thus there may be NO parents! > > I think you're getting ahead of us. How much of a DNA contribution is > worthy of note? The three people involved contributed DNA as follows: Mother: 23 chromosomes, around 3 billion DNA "letters" Father: 23 chromosomes, around 3 billion DNA "letters" Egg donor woman: mitochondrial DNA, about 16,000 DNA "letters" The mitochondria are sometimes called the "power plants" of the cell because they produce ATP, a molecule that is an essential source of energy for all of the other chemical processes going on within a cell. The fact that they have their own DNA, independent of the nucleus of the cell, is intriguing, and has led biologists to hypothesise that the mitochondria are actually descendants of ancient bacteria which formed a symbiotic relationship with other organisms early in the history of multi-cellular life on Earth. However, the mitochondrial DNA is tiny in comparison with the 46 chromosomes that we inherit from our parents: 16,000 DNA "letters" compared to six billion. It is also tiny in terms of the number of genes it contains: a mere 37, compared to the estimated 20,000 to 25,000 genes that are contained in the chromosomes. The mitochondrial DNA does not carry any of the genes for characteristics that we normally regard as inherited, such as hair colour, height, and so forth. In that sense, it doesn't make much of a contribution from a genealogical standpoint. However, it can, unfortunately, contain errors, and these can give rise to genetic defects in the same way as defective genes on the chromosomes. A mother with a genetic defect in her mitochondrial DNA would pass that on to all of her children, since we inherit our mitochondrial DNA solely from our mothers. The purpose of the research that was reported this week is to help such women to have healthy children. The donor woman would be someone without a defect in the mitochondrial DNA. I hope this helps to clarify things. David Harper Cambridge, England

On Wed, 06 Feb 2008 12:42:26 GMT, David Harper <devnull@obliquity.u-net.com> wrote: >The three people involved contributed DNA as follows: > >Mother: 23 chromosomes, around 3 billion DNA "letters" >Father: 23 chromosomes, around 3 billion DNA "letters" >Egg donor woman: mitochondrial DNA, about 16,000 DNA "letters" > >The mitochondria are sometimes called the "power plants" of the cell >because they produce ATP, a molecule that is an essential source of >energy for all of the other chemical processes going on within a cell. > >The fact that they have their own DNA, independent of the nucleus of the >cell, is intriguing, and has led biologists to hypothesise that the >mitochondria are actually descendants of ancient bacteria which formed a >symbiotic relationship with other organisms early in the history of >multi-cellular life on Earth. > >However, the mitochondrial DNA is tiny in comparison with the 46 >chromosomes that we inherit from our parents: 16,000 DNA "letters" >compared to six billion. It is also tiny in terms of the number of >genes it contains: a mere 37, compared to the estimated 20,000 to 25,000 >genes that are contained in the chromosomes. > >The mitochondrial DNA does not carry any of the genes for >characteristics that we normally regard as inherited, such as hair >colour, height, and so forth. In that sense, it doesn't make much of a >contribution from a genealogical standpoint. > >However, it can, unfortunately, contain errors, and these can give rise >to genetic defects in the same way as defective genes on the >chromosomes. A mother with a genetic defect in her mitochondrial DNA >would pass that on to all of her children, since we inherit our >mitochondrial DNA solely from our mothers. > >The purpose of the research that was reported this week is to help such >women to have healthy children. The donor woman would be someone >without a defect in the mitochondrial DNA. > >I hope this helps to clarify things. Thank you, yes it does help to clarify them. But, if I understand you correctly, even if the children were healthy, they would still pass on defective mitochondrial DNA to *their* children? -- Steve Hayes from Tshwane, South Africa Web: http://hayesfam.bravehost.com/stevesig.htm Blog: http://methodius.blogspot.com E-mail - see web page, or parse: shayes at dunelm full stop org full stop uk