PCR

Question 1

What does PCR stand for?

Answer 1

polymerase chain reaction

PCR is a method used to replicate DNA in vitro.

Question 2

What is the main purpose of PCR?

Answer 2

To replicate DNA in vitro

PCR mimics the natural process of DNA replication that occurs inside cells.

Question 3

What type of replication does PCR reproduce?

Answer 3

semiconservative replication

This refers to the way DNA strands separate and serve as templates for new strands.

Question 4

What do both PCR and DNA replication use to build new DNA strands?

Answer 4

DNA polymerase

DNA polymerase adds nucleotides to the growing DNA strand.

Question 5

What is required to start DNA synthesis in both processes?

Answer 5

Primers

In DNA replication, RNA primers are used, while synthetic DNA primers are used in PCR.

Question 6

What is the first step of PCR?

Answer 6

Melting (denaturing)

The DNA is heated to 95 degrees to separate the strands.

Question 7

What occurs during the annealing step of PCR?

Answer 7

Primers bind to single-stranded DNA

The temperature is lowered to 50-65 degrees to allow this binding.

Question 8

What temperature is used during the extension step of PCR?

Answer 8

72 degrees

At this temperature, Taq polymerase adds nucleotides to build the new DNA strand.

Question 9

How many cycles are typically used in PCR?

Answer 9

30 cycles

Each cycle doubles the amount of DNA between the primers.

Question 10

What is Taq polymerase and why is it important?

Answer 10

A DNA polymerase that withstands heat

Discovered in Thermus Aquaticus, it remains stable at high temperatures, unlike most DNA polymerases.

Question 11

What is the typical length of PCR primers?

Answer 11

15-30 bases (nucleotides)

This length is necessary for effective binding to the target DNA.

Question 12

What are the two types of primers used in PCR?

Answer 12

Sense strand primer and antisense strand primer

Each primer is complementary to one strand of the DNA.

Question 13

In which direction does a new DNA strand grow during PCR?

Answer 13

5’ to 3’ direction

This is a fundamental aspect of DNA synthesis.

Question 14

What does amplification mean in the context of PCR?

Answer 14

Making many copies of a specific DNA region

The area between two primers is specifically amplified.

Question 15

What is necessary to design effective primers?

Answer 15

Know the DNA sequence of the target region

Primers must be complementary to the target DNA for successful amplification.

Question 16

True or False: The primers in PCR are RNA molecules.

Answer 16

False

PCR uses synthetic DNA primers, not RNA.