Answer: 1-4-5-6
Explanation: Polymerase Chain Reaction or PCR is a lab technique used to make numerous copies of determined section of a DNA. The process requires 5 ingredients to perform:
1) The DNA template to be copied, which can be obtained by disrupting the nuclear membrane of a cell and releasing its components into a solution;
2) Short sequences of DNA, called primers, designed to be complementary to the DNA to be copied;
3) DNA nucleotide bases, also known as dNTPs (A, T, C and G);
4) Taq polymerase enzyme;
5) Buffer to ensure optimal conditions to the reaction;
PCR involves three stages:
- Denaturing: this stage takes 15 to 30 seconds and consists of putting the DNA and the other ingredients in a thermal cycler, heated to 94-95°C. In that temperature, the DNA to break into two strands, in a process called Denaturation;
- Annealing: the temperature is reduced to 50-65°C, so the primers can attached itself to a specific location on the stranded DNA. This step initiates the synthesis, because the polymerase enzyme can only add bases to a double strand of DNA. Once bounded, it takes 10 to 30 seconds to make a new complimentary strand of DNA from the model;
- Extending: In this stage, the temperature is increased to 72°C, which enables the Taq polymerase enzyme. This enzyme comes from a bacteria, which supports high temperatures, and has a role of builiding the complimentary strand by binding the primer and adding the DNA bases to the single strand. This creates a new molecule of DNA. The time this step takes depends on the length of the DNA to be copied;
