DNA History

Fredrick Griffith  Identified transformation of rough coat bacteria ( non lethal) to smooth coat (lethal)  Injected mice  Showed that something is passed from one bacteria to another

Oswald Avery  Discovered that DNA is the material of which genes and chromosomes are made

Alfred Hershey and Martha Chase  Proved DNA was the only genetic material not proteins  Study was done with bacteria  Used radio active isotopes

Erwin Chargaff  Discovered two rules  Guanine equals cytosine, adenine equals thymine  The amounts change in different species

Rosalind Franklin  Created pictures of DNA with X-ray diffraction

James Watson and Francis Crick  Came up with DNA as a Double Helix  Like a winding stair case  The strictness of base-pairing results in two strands that contain complementary base pairs.  The double helix consists of a backbone made of sugars and phosphates and alternating bases called nucleotides

Why is DNA important?  Our traits (alleles and genes) are inherited by our ancestors, but how do those traits tell our bodies to look the way we look? It’s a code.  Genes are made of DNA, a large, complex molecule. DNA is composed of individual units called nucleotides. Three of these units form a code. The order, or sequence, of a code and the type of code determine the meaning of the message.

Messages from the inside?  DNA (Deoxyribonucleic Acid) is the genetic information of all living organisms stored in units called genes  A gene is a sequence of DNA that codes for a protein  These proteins make up our traits!!!

Where can we find it? DNA up close! Individual Nucleotides Double stranded DNA molecule cell nucleus chromosome

Nucleotides  A nucleotide is the monomer of DNA  Nucleotides are small molecules made up of three parts 1. A deoxyribose (sugar) 2. A phosphate group 3. A nitrogenous group

DNA’s Four Nucleotides Adenine (A)Guanine (G)Cytosine (C)Thymine (T) Deoxyribose Phosphate group Purines Prymidines

Rungs of the Ladder are pairs of nitrogenous bases

Let’s put it all together! Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Hydrogen bonds Nucleotide Sugar-phosphate backbone