DNA Replication

When a parent cell undergoes cell division and beomes 2 daughter cells, a copy of the genetic information must be made so that each of the daughter cells can have a copy. This is when DNA replication occurs. DNA replication is semi-conservative, which means that each new copy of DNA contains one of the original DNA strands. The DNA splits apart, and half of the old strand becomes a template for the new strand being created, so that there is always a piece of the original DNA intact.

Steps To Replication:

1.Unzipping: the hydrogen bonds between the bases are cut, with the enzyme helicase. When the hydrogen bonds are broken, the DNA is unzipped.

2. Complementary Base Pairing: once the two sides of DNA are seperated from each other, the new bases come in and join the original bases. Adenine will always bind with thymine, and guanine with cytosine. This takes a lot of energy, so ATP energy is used to build the new molecule.

3. Form New Sugar-Phosphate Backbone: because the new strand does not have anything holding it together yet, a new sugar-phosphate backbone must be formed. This is done with the help of DNA polymerase. A hydrogen bond is formed between the sugar and the phosphate, while the DNA polymerase also checks for mistakes.

4. Two Identical Strands of DNA Formed: two semi-conservative strands of DNA are formed. These strands are identical to each other, assuming that no mistakes have been made in the process.

This animation shows the entire process of DNA replication:

http://www.youtube.com/watch?v=K6-ciqZtFqI

Adenine Triphosphate

Adenine triphosphate is thought of as a nucleic acid because it has the same structure as a nucleotide. The difference between ATP and other nucleotides is that ATP has 3 phosphate groups, as opposed to just one. ATP energy is the main energy source for the body. Glucose is turned into ATP by the mitochondrian in our cells. It stores energy well because a lot of energy is used to bind the 2 phosphate molecules together because they are both negative, so when that bond is broken, a lot of energy is released.