Science Log: DNA Bubble Map Pg. 23 in your science log section

DNA Structure: What does DNA look like?

What are genes? Passed from one generation to the next (determine inherited characteristics, such as eye color) Found on chromosomes (which are made of DNA) Contain the information to: Build and maintain cell parts Be copied each time a cell divides (The Cell Cycle)

DNA’s parts DNA is made of NUCLEOTIDES Each nucleotide has: Sugar Phosphate Base containing nitrogen

4 types of bases There are 4 types of bases Adenine Thymine Guanine Cytosine In the 1950s, Chargaff discovered that the amount of A and T are equal and G and C are equal. (Chargaff’s Rules)

Rosalind Franklin British scientist who used x-ray images to determine the spiral shape of DNA

Watson and Crick’s Model Watson and Crick studied the work of Chargaff and Franklin to determine the structure of DNA Figured that it is a “double helix”: Twisted ladder

How does DNA replicate? Replicate = copy Watson and Crick also figured out how DNA replicates! Steps to replicate: “Double Helix” unwinds Ladder unzips New nucleotides come in to make two new strands

Steps to replicate: 1. “Double Helix” unwinds and unzips Enzyme (chemical) called helicase does this

Next, the exposed bases on each strand find new nucleotide partners

The end result!