3.5 IB PCR

What is the purpose of PCR?

• To produce millions of copies of the DNA genome

• To produce millions of copies of a specific region of DNA

• To add nucleotides to a DNA sequence

• To watch polymerase work.

Answer explanation

Usually when PCR is used only certain sections of DNA are amplified.

What does PCR stand for?

• Polymerase Cytoplasmic Reaction

• Polymerase Chromosomal Reaction

• Polymerase Chain Reaction

• Probably Cannot React

Answer explanation

What happens in the denature step of PCR?

• The DNA nucleotides are broken apart.

• The base-pairing rules for DNA are reversed.

• The double-stranded DNA is separated into two single strands of DNA.

• The DNA is returned to its natural setting.

Answer explanation

Denature usually means breaking up or pulling apart. You don't want to break apart a strand of DNA but you do want to pull the two strands apart so you can access the nucleotides.

At what temperature does the denature step of PCR occur?

• 94-96° C

• 50-65° C

• 72° C

• Any temperature

Answer explanation

It has to be HOT, HOT, HOT!

Tags

NGSS.HS-PS1-5

At what temperature does the anneal step of PCR occur?

• 94-96° C

• 40-60° C

• 72° C

• Any temperature

Answer explanation

Annealing is when the primers are added, so it has to be on the 'cooler' side of the process.

At what temperature does the extension step of PCR occur?

• 94-96°C

• 50-65°C

• 72°C

• Any temperature

Answer explanation

Extension or elongations happens using Taq polymerase that comes from thermophile bacteria which love it HOT, HOT, HOT!

Tags

NGSS.HS-PS1-5

What happens during the anneal step of PCR?

• Primers are created.

• The primers attach to the target DNA region.

• Primers copy the new DNA strand.

• Primers sequence DNA

Answer explanation

This has to happen at relatively cooler temperatures for the primers to stick.

What is the function of a primer?

• To identify the particular region of DNA to be copied by PCR.

• To copy DNA.

• To create DNA nucleotides.

• To maintain the temperature of the PCR reaction.

Answer explanation

Just as in DNA replication, a primer allows the polymerase a starting point to bind to.

What is the purpose of the extension step of PCR?

• To create the primers.

• To extend the time it takes to produce DNA.

• To allow polymerase to create the complementary strands of DNA.

• To allow substrates to copy DNA sequences.

Answer explanation

This step is aka as elongation and it is the 'building' of the complimentary strand.

If the target sequence is GCATTA, what is the complementary sequence?

• CGUAAU

• CGTAAT

• CGTUUT

• GCATTA

Answer explanation

Remember, PCR is a way of doing DNA replication in vitro, or outside of the cell, so there will be no uracil.