1. Mitochondrial DNA was extracted from a molar of a 9000 year old skeleton foun
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Question
1. Mitochondrial DNA was extracted from a molar of a 9000 year old skeleton found in Cheddar Gorge, England. Would you expect this DNA to be comparable to modern human DNA?
2. There were reports in the literature several years ago that DNA had been recovered from dinosaur fossils and amplified and sequenced. But the genes obtained appeared to be human. What is the explanation?
3. Suppose that the sequences of two proteins each consisting of 200 amino acids are aligned and that the percentage of identical residues has been calculated. How would you interpret each of the following results in regard to the possible divergence of the two proteins from a common ancestor?
a. 80% b. 50% c. 20% d. 10%
Explanation / Answer
1. Mitochondrial DNA was extracted from the molar teeth of the old skeleton suggest that , the hyper variable regions of the were the most and nut only change occurs .the mitochondrial DNA can be thought as a circle or loop which breaks at the during the process of the reproduction , the mitochondria are seperate from the chromosome and reproduce seperatly .so it is very difficult to compare between the two becaus e as teher will be hundreds of mitochondria within the cell ,it is exttremly small in comparision with millions of base pairs in single chromosome ,this gives the level of resoulution at the perticular maternal lineage it is passed form mother to the daughter with lower rate of mutation than the Y chromosome as son do not pass the mt DNA the offspring .
2. there is an evidance that dinosaur has the soft tissues ,collagen fibers and RBC cells but mammals are the unsual among the vertebrates that lacks the cell nucleus , if fossils cells have the nuclei they could not be humans . As the fossilisation is rare , dinausours have found on the very contininet that humans are inhabitated so theer might b e mix up of the DNA during the fossilization process as there is evidance that they live togather in the past according to lyon and butt 2008 eiditon as the Dinosaur is a cold blooded animal and humans are warm blooded.
3. 80 percent ; almost certainly diverged from the common ancestor ,50. percent also might have certainly diverged from the common ancestor 20 percent , they might have diverged from the common ancestor ,but sequence alignment may not provide the supproting evidance . 10 percent , they might have diverged from the common ancestor ,but sequence alignment is unlikely provide supproting evidance
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