DNA Damage | Oxidative Based Damages

DNA Damage

Whether DNA is degraded or intact, this can be seen through agoras gel electrophoresis but in this case. The high amount of DNA is consumed. In forensics, we have a limited amount of DNA to the cape.

The upper layer of skin gets replaced every 15 days so there are dead cells present fingertips. If 3-4 such cells are obtained then they have enough DNA but if a bloodstain is obtained then a large number of WBCs will be present in it.

When an individual dies then the DNA is exposed own nucleases as well is bacterial fungal nucleases will degrade it. More the old DNA more there will be degradation.

Oxidative Based Damages

Due to oxygen, the binding of sugar base gets affected as a result of which a basic DNA will be obtained (no base). Moreover, there will be nicked. It also depends on the degree of degradation if it is completely degraded then there will be small pieces.

If DNA is in dry place then it will not degrade much. There are some other factors as well which can degrade DNA as:

1. Freeze thawing the DNA, again and again, can cause damage dNTPs to get degraded.
2. Vortex also causes damage

Before the discovery of destruction endonucleases, for cloning purposes, DNA used to be vortexed for shearing it. These pieces were then cloned but there cannot be any cloning by vortexing shearing DNA because pieces will be large and the sticky ends produced will not be complementary.
DNA has to be converted into blunt end products S1 nuclease will be used (single strand-specific nuclease) as it is specific for a single-stranded end. It converts sticky ends into a blunt. Blunt ended ligation needs more DNA (it is 10 times less efficient).
More amount of vector has to be chosen.

When DNA is in less amount and its quality has to be checked then Real-Time PCR or Simple end Product PCR is good. STR sequence primers can be used. Real-time PCR is more good to check the quality of DNA as it doesn’t waste DNA.

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