Future of Forensics

1. PCR is started by transferring extracted DNA into a PCR tube. Since PCR is done by heating and cooling the DNA multiply times, the PCR tubes are made to have an even heat distribution.

2. Then add a primer 1 and primer 2 to the PCR tube. The primers will attach to the ends of the segments that is being copied so the right segments are copied.

3. Add DNA bases (adenine, cytosine, guanine, and thymine) to the PCR tube. These bases will create the DNA copies. 

4. Add DNA polymerase to the PCR tube. DNA polymerase are molecules that reads the DNA and correctly pairs it with its base. Since PCR occurs at a high temperature, choose a type of DNA polymerase that can withstand high heat.

5. Place the PCR tube into a DNA thermal cycler. This machine will accurately heat and cool the DNA at certain times in an hour.

6. Inside the thermal cycler, it will heat up to 95˚C. This will cause the two strands of DNA to unravel.

7. Then it will cool down to 50˚C, causing the single-stranded DNA to naturally pair up again. However, since primers were added, they will attach to their location before the two strands rejoin.

8. The temperature will rise up to 72˚C, activating the DNA polymerase. When the DNA polymerase finds an attached primer, it begins pairs complementary bases.

9. Repeat steps six through eight to form copies.

10. After this process is completed, it will form two desired DNA segments. As the process continues, more segments would be formed; after only thirty cycles, billions of copies will be made.

 

(Source: PCR)