DNA Replication Activity Day

Today we started off with the following Daily Question looking at the difference between Prokaryotic and Eukaryotic Replication.

Monday April 16^th

How does Prokaryotic and Eukaryotic DNA replication differ?

In the number of replication points. 

How many points of replication do prokaryotic cells have?

Just one - remember, Prokaryotic cells DNA is found inside the nucleus in a single circular loop.  This loop will open up in one spot and proceed in either direction until they meet again.  They will then split from each other.

About how many points of replication do eukaryotic cells have?

MANY - (About 100)  Remember, Eukaryotic DNA is found inside the nucleus in the form of many chromosomes.  If each Chromosome started at one side and went the other it would take over 30 days for all the DNA to replicate.  We know that our cells divide much quicker than that, so that is why it is so important to have many points of replication.

The arrows show how there are MANY different points of replication in Eukaryotic DNA.

By having more points of replication does DNA replication happen slower or faster? Faster

We then worked with the K'nex Models and went through DNA replication.  First I had you build your original DNA molecule from last week.

Making Original DNA model

After reviewing all the different parts of the DNA molecule (deoxyribose, Phosphate groups, hydrogen bonds, nucleotide bases) I had you go through DNA replication.

 First you acted as DNA Helicase by Unzipping the nucleotides by breaking the Hydrogen bonds.

Breaking Hydrogen bonds (Acting as DNA Helicase)

You then acted as DNA polymerase by adding new nucleotide bases to either side.

New Bases are added to BOTH sides

Adding new bases - playing the role of DNA Polymerase 

At the end of replication you had two identical DNA molecules.  Each had one "old" strand - or template strand and one "new" strand or daughter strand.

Two exact DNA molecules each with one old (gray) and one New (yellow) strand

Note how the Old of one is the New of the other and vise versa

Ultimately what you just created was "sister chromatids"  that will now allow the cell to go through mitosis. (remember that the chromosomes line up in the middle and pull apart leaving you with two genetically identical nuclei and then two identical cells form after cytokinesis.)