DNA Replication

If a strand reads:
3' A A A T T T C 5'
The matching strand would read...

• 5' T T T A A A G 3'

• 3' T T T A A A G 5'

• 5' A A A T T T C 3'

• 3' U U U A A A G 5'

What is the end result of DNA replication?

• Two identical DNA molecules each composed of one new and one original strand

• Two non-identical DNA molecules each composed of one new and one original strand

• Two identical DNA molecules. One is made up of the two old strands and one is made up of the two new strands.

• Two non-identical DNA molecules. One is made up of the two old strands and one is made up of the two new strands.

What is the function of DNA Helicase?

• Unzips” the strand of DNA

  Breaks the hydrogen bonds so that new nucleotides can be added

• Bind to separated strands of DNA to keep the strands separate

• Creates a strand of RNA nucleotides

  DNA nucleotides must be added to something. Primase creates a strand of nucleotides that DNA Polymerase I can add nucleotides to. It is not in the final product.

• Removes/replaces the RNA primer. Proofreads new DNA strand.

What is the function of single stranded binding proteins?

• Unzips” the strand of DNA

  Breaks the hydrogen bonds so that new nucleotides can be added

• Bind to separated strands of DNA to keep the strands separate

• Creates a strand of RNA nucleotides

  DNA nucleotides must be added to something. Primase creates a strand of nucleotides that DNA Polymerase I can add nucleotides to. It is not in the final product.

• Removes/replaces the RNA primer. Proofreads new DNA strand.

What is the function of DNA Primase?

• Unzips” the strand of DNA

  Breaks the hydrogen bonds so that new nucleotides can be added

• Bind to separated strands of DNA to keep the strands separate

• Creates a strand of RNA nucleotides

  DNA nucleotides must be added to something. Primase creates a strand of nucleotides that DNA Polymerase I can add nucleotides to. It is not in the final product.

• Removes/replaces the RNA primer. Proofreads new DNA strand.

What is the function of DNA Polymerase I?

• Unzips” the strand of DNA

  Breaks the hydrogen bonds so that new nucleotides can be added

• Bind to separated strands of DNA to keep the strands separate

• Creates a strand of RNA nucleotides

  DNA nucleotides must be added to something. Primase creates a strand of nucleotides that DNA Polymerase I can add nucleotides to. It is not in the final product.

• Removes/replaces the RNA primer. Proofreads new DNA strand.

What is the function of DNA Polymerase III?

• Removes/replaces the RNA primer. Proofreads new DNA strand.

• Adds nucleotides to RNA primer, thus synthesizing a new strand of DNA. Has a “proofreading” role.

• Relaxes DNA from super coil so it can be replicated.

• Joins fragments of DNA together.

What is the function of topoisomerase?

• Removes/replaces the RNA primer. Proofreads new DNA strand.

• Adds nucleotides to RNA primer, thus synthesizing a new strand of DNA. Has a “proofreading” role.

• Relaxes DNA from super coil so it can be replicated.

• Joins fragments of DNA together.

What is the function of DNA Ligase?

• Removes/replaces the RNA primer. Proofreads new DNA strand.

• Adds nucleotides to RNA primer, thus synthesizing a new strand of DNA. Has a “proofreading” role.

• Relaxes DNA from super coil so it can be replicated.

• Joins fragments of DNA together.

Place the steps of DNA replication in order.

• The double helix unwinds using DNA helicases

• Enzymes known as DNA polymerases move along each of the DNA strands

  Add nucleotides to the exposed nitrogen bases forming two new strands of DNA

• The process continues until all of the DNA has been copied and the polymerases are signaled to detach