Olivia's+Notes

3.How and why does it copy itself?

DNA copies itself because when cells are divided, new genes are necessary for the cell to function. Genes are made up of DNA so it is crucial to copy the DNA before the cell divides. How does it copy itself? Well, the DNA molecule starts out as a double helix. Then when the DNA replicates itself, the two sides of the molecule twist so that they are unwound and separate. The four main bases that link the two strandes of DNA molecules are guanine, thymine, cytosine, and adenine. These bases have hydrogen bonds that are broken when the DNA replicates itself. The DNA separates from between paired nitrogen bases and then the nitrogen bases join with the last of either side of the DNA molecule and form hydrogen bonds. The order of the bases of the replicated pair is the exact same as the original DNA molecule.

See below for a video about how Cells Divide: media type="file" key="how-cells-divide.swf" width="360" height="270"

Below is the DNA Replication Song:

media type="youtube" key="dIZpb93NYlw" height="315" width="420"

URL: http://www.youtube.com/watch?v=dIZpb93NYlw

4.What are genes and where are genes found?

A gene is something that determines a trait (gender, hair color, eye color, etc). Chromosomes are what carry the genes from parent to offspring. Genes can be found in chromosomes, which can be found in the nucleus of all cells. <-- Genes!