DNA

What is DNA?  DNA stands for deoxyribonucleic acid  It is the code for a cell  Tells the cell  What to do  Where to go

Forms of DNA  Multiply forms because DNA can’t perform all of its functions in one form  Chromatin  Tangled mass of DNA and proteins  Not organized  Instructions  Chromosomes  DNA after replication  Attached to a copy with a centromere  Chromatid  DNA is organized  Rod like structures  More easily divided

What is DNA made of?  Phosphate group  5 carbon sugar  Nitrogenous Base  Purines  Adenine  Guanine  Pyrimidines  Cytosine  Thymine

Base Pairs  Adenine pairs with Thymine  Always Together  Apple in the Tree  Always Tackle  Cytosine pairs with Guanine  Constantly Glued  Corn in the Ground  Constantly Guard

How is DNA held together?  Hydrogen Bonds  Positive hydrogen atoms are attracted to negatively charged atoms  Specifically Nitrogen, Oxygen or Fluorine  Only occur in polar molecules  Relatively weak

Structure of DNA  Double Helix  Looks like a twisted ladder  Base pairs are the rungs  The backbone consists of the 5 carbon sugar and the phosphate group

Scientists who helped discover structure of DNA  Rosalind Franklin  Did x-rays to determine shape  Discovered DNA was twisted  Large groups of molecules were evenly spaced  Erwin Chargaff  equal amounts  A and T  G and C  Watson and Crick  Base Pairing  Double Helix

Replication of DNA  Enzyme unzips the helix  Each of the two sides acts as a template  New complementary bases are brought in  Insert new sugars-phosphate links

DNA’s Importance in Today’s Society  Medical research to determine if someone is at a higher risk for disease  Forensics  Identification of victims/ criminals  Agriculture  Used to breed animals to be more disease resistant  Make more nutritious produce