Warm-up Essential Question What does DNA do for us? What is the structure of DNA and how does it replicate itself for mitosis?

What’s in your jeans (genes)? DNA What’s in your jeans (genes)?

I. DNA Deoxyribonucleic Acid A. Location 1. in nucleus 2. what makes up chromatin B. Chromosomes- contain genetic information 1. Genes- sequence of DNA that codes for a protein and thus determines a trait 2. Chromatin- consists of tightly coiled DNA around proteins

C. Nucleotide- the base unit (monomer) of DNA C. Nucleotide- the base unit (monomer) of DNA. Made up of a sugar, phosphate group, and a nitrogenous base 1. Backbone of DNA- 2 components: a. 5 carbon sugar b. phosphate group

2. Nitrogenous base- nitrogen containing molecule that makes up “step” or “rung” of ladder. 2 groups: A. Purines- molecule made of 2 rings, 2 types: 1. Adenine 2. Guanine B. Pyrimidines- molecule made up of 1 ring, 2 types: 1. Cytosine 2. Thymine C. Chargaff’s rule: A=T and C=G

A + T + C + G = 100% of genes You can figure out how much of each gene type an organism has

Discovered by Watson and Crick D. Structure of DNA 1. Double Helix Discovered by Watson and Crick Twisted ladder or spiral staircase 2. Histone- protein molecule around which DNA is tightly coiled in chromatin.

E. Replication- copying process by which a cell duplicates its DNA, takes place during interphase 1. makes 2 complimentary DNA strands, results in identical copies of DNA 2. Nucleotides added on both original strands in opposite directions 3. Nucleotides added one at a time 4. DNA Polymerase- enzyme that “proofreads” the new DNA strand, helps to make sure it is a near perfect copy 5. Replication fork- site where separation and replication occur.