DNA replication

Today we talked about DNA replication and the enzymes involved. Can you answer the questions below?

1. Why do we need DNA replication?

2. What are the leading and lagging strands?

3. What is the name of the enzyme that unwinds the DNA for replication? What other molecule is involved in this process?

4. What does DNA Polymerase III do in replication?

5. What enzyme "glues" the Okazaki fragments together?

Below is the website you used to review these questions
DNA replication

Here is another great site to help you understand replication
More DNA replication

Here is a great video about Replication



Here is Mr. Anderson explaining replication. (You don't need to know about mitosis and binary fission)

DNA structure and Homework for Monday

On friday we began talking about the Structure of DNA (Deoxyribonucleic Acid)

The 3 main parts of a DNA molecule are:



1. The Sugar: Ribose







2. A Phosphate group:  (what do you think the X stands for?)







3. A Nitrogenous Base (Adenine, Guanine, Cytosine, Thymine and Uracil - this is a special one that is in RNA only)

One of each of these together makes up a Nucleotide:

As we begin to build a DNA molecule, how are the nucleotides connected to each other to build the rung of the ladder? 

Hydrogen Bonds! What are the numbers of the Carbons in the ribose sugar? What Carbon is the "1st" Phosphate group connected to? The 5' (five prime) Carbon. The phosphate of the next nucleotide is connected by the 3' Carbon. This is way when we discuss DNA we say it goes in the 5' to 3' direction. How are the nucleotides bonded to each other (i.e. the sides of the ladder)? Covalent bonds.

Why would you want the middle to be Hydrogen, and therefore weaker, but the sides be Covalent bonds (stronger)? 

Finally, your homework for Monday is to continue with the handout on DNA structure and replication. If you finish that one you should then begin the 2nd DNA handout (it has the website from BioTeach on the top).