Ch 4 Lesson 4

specific function of each enzyme DNA helicase RNA primase DNA polymerase DNA ligase

-Unwinds the double helix by *breaking H bonds* which forms a *replication bubble* consisting of 2 *replication forks* -Builds an RNA primer on leading & lagging strands -Adds daughter nucleotides on the parent strands -Binds Okazaki fragments to form a continuous strand THESE ARE THE 4 MAIN ENZYMES OF DNA REPLICATION

DNA replication is what? The 2 parents strands of DNA a replicated how in relation to each other

-discontinuous -not replicated the same, the *leading strand* gets DNA primer 1st, is continuous, & easier for DNA polymerase to read-replication occurs as quickly as the replication fork opens up. The *lagging strand* is 2nd & discontinuous, it's not exposed the same/as easily for DNA polymerase to read. RNA primer is needed for each Okazaki fragment

How many rounds of DNA Replication were needed to disprove the Conservative method? In which method of DNA Replication would new DNA consist of alternating parent and daughter DNA? Who performed the experiment that proved semi-conservative DNA replication was correct?

1 dispersive Meselson and Stahl

During the process of DNA replication what happens in order

1. the double helix is unwound by *DNA helicase* 2. *RNA primase* then builds an RNA primer on the parent strand to signal DNA polymerase 3. *DNA polymerase* adds complementary nucleotides to the parent strand to form 2 new daughter strands of DNA 4. After all bases are matched *DNA ligase* joins the Okazaki fragments together to make a new daughter strand of DNA

Why do we call DNA an antiparallel molecule? Why can't DNA polymerase work continuously on both parent strands?

Because the 3' and 5' ends of each strand run in opposite directions. DNA polymerase builds a strand of DNA in the 5' to 3' direction, so it only works on the strand of DNA that runs in the 3' to 5' direction.

The order of enzymes in DNA replication include the following:

DNA helicase, RNA primase, DNA polymerase, & DNA ligase

Why is it important how many replication bubbles there are during replication?

During the replication of 1 DNA molecule there are multiple replication bubbles, this ensures DNA can make a copy of itself quickly. In order to complete replication, the replication bubbles grow & merge together

Where are hydrogen bonds located within the DNA? Because hydrogen bonds are weak bonds, they create a perfect site for _____ What is the purpose of the RNA primer?

In the center of the molecule linking the nitrogen bases of both strands separating nucleic acid strands initiate the process of DNA replication

Why is it necessary that the DNA helicase unwinds the DNA?

It exposes the nitrogenous bases of the nucleic acid chain so that new nucleotides can be added to create the daughter strand.

Which is the enzyme that builds the RNA primer? Which is the enzyme that attaches daughter nucleotides to the parent strand during DNA replication?

RNA primase DNA polymerase

DNA replication occurs during the ___________ of the cell cycle. DNA replication must occur before a cell divides to ensure that both cells _________________

S Phase (synthesis phase) get a copy of DNA in their nuclei

When DNA ligase binds Okazaki fragments together what happens

This creates a completely new DNA strand for each parent DNA strand. After the Okazaki fragments are connected, the 2 new DNA strands are formed

What are the small components (monomers) that make up the large DNA polymer? What happens to the RNA primer once DNA replication is begun by DNA polymerase

nucleotides the primer is removed

The location where the process of DNA replication begins is called the _____. When DNA helicase separates the two parental strands, it creates a Y-shape called a _____.

origin of replication replication fork

The Dispersive method of DNA Replication was disproved when the scientists observed... What is the cellular process in which a new copy of DNA is created?

two separate bands of DNA of different densities. DNA replication