Is it possible for you not to inherit one of your granparents DNA yet still show a physical similairity in your body's features to that grandparent? I guess what I want to find out is if you can inherit the catlaytic reaction of RNA polymerase with DNA from a grandparent but not their DNA itself; since isn't a chromosome which contains DNA the same structure/genetic sequencing for all human beings?
Marc,
Of course you inherit your grandparents DNA. You received one set of 23 chromosomes from your mum, the other 23 from your dad, and they each did the same from their parents. So from a very simplistic point of view, you will have 1/4 of your DNA that is similar to each of your 4 grandparents.
It is slightly more complicated than that however: (1) You will actually have more in common with your maternal grandmother, since you will have received her mitochondrial DNA (mtDNA) through your mother, and none of the mtDNA from the other grandparents or your dad, (2) you will have some differences due to spontaneous mutation from environmental influence and an imperfect cellular repair system, and (3) which is not too dissimilar to what you have said, there are epigenetic changes that can be inherited, which mare modifications to the DNA that do not change the actual DNA sequence. These have bene linked to a number of inheritable traits, including mouse coat colour through to some diseases, where the DNA is the same sequence, but the trait is different.
Chromosome structure will largely be the same between people. The sequence however is not the same. The human genome is made up of over 3 billion bases, of which about 1/1000 base on average is different. Therefore, (in another overly simplistic world), approximately 3,000,000 bases are different between you and me (that is still 99.9% similar overall). Why do you think we all look different / have different susceptibility to disease./ react differently to drugs etc?
Hope that helps,
Steve
Marc,
Of course you inherit your grandparents DNA. You received one set of 23 chromosomes from your mum, the other 23 from your dad, and they each did the same from their parents. So from a very simplistic point of view, you will have 1/4 of your DNA that is similar to each of your 4 grandparents.
It is slightly more complicated than that however: (1) You will actually have more in common with your maternal grandmother, since you will have received her mitochondrial DNA (mtDNA) through your mother, and none of the mtDNA from the other grandparents or your dad, (2) you will have some differences due to spontaneous mutation from environmental influence and an imperfect cellular repair system, and (3) which is not too dissimilar to what you have said, there are epigenetic changes that can be inherited, which mare modifications to the DNA that do not change the actual DNA sequence. These have bene linked to a number of inheritable traits, including mouse coat colour through to some diseases, where the DNA is the same sequence, but the trait is different.
Chromosome structure will largely be the same between people. The sequence however is not the same. The human genome is made up of over 3 billion bases, of which about 1/1000 base on average is different. Therefore, (in another overly simplistic world), approximately 3,000,000 bases are different between you and me (that is still 99.9% similar overall). Why do you think we all look different / have different susceptibility to disease./ react differently to drugs etc?
Hope that helps,
Steve
@Steve: so you'd expect that there is high similarity for bases coding for eye colour among the population compared to nose shape since there are more people that have the same eye colour than there are nose shape; or are there subtelities in eye colour that can make the range of eye colour pigments essentially unlimited like nose shape, thus you'd find high variabilility in bases coding for eye colour even in people with very similar eye colour phenotype?
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