Open Question
Why was it important to include a positive control and a negative control in the PCR analysis?
18. Biotechnology
The Steps of PCR
Struggling with General Biology?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
In the polymerase chain reaction (PCR) technique, a heating phase and a cooling phase alternate. An original sample of DNA would have to pass through how many total rounds of heating and cooling before a sample is increased eight times in quantity?
A
Two
B
Four
C
Six
D
Eight
E
Three
Verified step by step guidance1
Understand that PCR is a technique used to amplify DNA, where each cycle of heating and cooling doubles the amount of DNA.
Recognize that each cycle consists of a heating phase (denaturation) and a cooling phase (annealing and extension).
Calculate how many cycles are needed to increase the DNA quantity eight times. Since each cycle doubles the DNA, you need to find how many times you need to double the DNA to reach eight times the original amount.
Use the formula for exponential growth: \(2^n = 8\), where \(n\) is the number of cycles. Solve for \(n\) to find the number of cycles needed.
Conclude that the number of cycles required is three, as \(2^3 = 8\), meaning three rounds of heating and cooling are needed to increase the DNA quantity eight times.
Related Videos
Related Practice
The Steps of PCR practice set
Problem sets built by lead tutorsExpert video explanations