<span>A photon of UV light causes mutations in the double-stranded DNA via a photochemical reaction. The product of such photochemical reaction in DNA is a cyclobutane pyrimidine dimer. Dimers may be repaired by mechanisms of photoreactivation or nucleotide excision repair (NER), but if the repair doesn’t occur dimers are mutagenic.
</span> <span>
UV light is absorbed by a double bond in pyrimidine bases (thymine and cytosine in DNA). The bond is opened and UV-modified base can now react with neighbouring molecules. If neighbouring molecule is another pyrimidine base, the UV-modified base forms direct covalent bonds with it. A cyclic ring (cyclobutane), not normally found in DNA, is formed (links the two pyrimidines). Next step is forming a single bond between two carbon atoms on the rings.The product of this reaction is a 6-4 molecule pyrimidine-pyrimidone which is more mutagenic than cyclobutane pyrimidine dimers.</span>
Explanation:
<em>Mitochondrial DNA typing</em><em> </em><em>-</em>
This method is mainly used by forensic scientist who investigate crime scenes.
It involves the use of DNA from an unknown sample to match a DNA collected from a crime scene.
This method is normally used in special scenarios.
These scenarios include:
1) When the DNA is discarded.
2) When the sample does not contain nuclear DNA.
From the description above we can now answer the question as follows:
an unknown nuclear mtDNA is matched to a nuclear mtDNA found at a crime scene.
Answer:
Petroleum, also called crude oil, is a fossil fuel. Like coal and natural gas, petroleum was formed from the remains of ancient marine organisms, such as plants, algae, and bacteria. ... Millions of years ago, algae and plants lived in shallow seas
Cells in your body work together, they form bones, and muscles. Cells, however cannot work alone, they must be able to work together. Each cell does a different thing.
