FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Chapter 12 DNA & RNA Section 12-1 DNA

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Griffith & Transformation Studying Natural Bacterial Pneumonia caused by:Studying Natural Bacterial Pneumonia caused by: –Streptococcus pneumoniae Smooth (pathogenic)Smooth (pathogenic) Rough (non-pathogenic)Rough (non-pathogenic) S. pneumonia in sputum Notice capsule Gram Positive Diplococci

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Streptococcus pneumonia Optochin Disc Type 3 VERY Mucoid

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Griffith’s Experiments Injected MiceInjected Mice –Smooth – Mice Died –Rough – Mice Didn’t Get Sick –Heat Killed Smooth – Mice Didn’t Get Sick Illness Not Caused By PoisonIllness Not Caused By Poison

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Mixed Heat Killed Smooth With Rough Live Bacteria. –Mice Died –Autopsy Revealed Lungs Full Of Smooth Strain of Bacteria HOW?? Transformation

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Griffiths Transformation

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Transformation Heat Killed Smooth BacteriaHeat Killed Smooth Bacteria –Still Contained The Information On How To Become Smooth –And Could Transmit That Info –And Transform Rough Bacteria To The Smooth (Pathogenic) Form

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Avery & DNA Repeated Griffith’s WorkRepeated Griffith’s Work But Treated The Extract From Heat Killed Smooth Bacteria To Destroy Specific Types Of CompoundsBut Treated The Extract From Heat Killed Smooth Bacteria To Destroy Specific Types Of Compounds

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Treated Extract To Destroy ProteinsLipidsCarbohydratesRNA Transformation Still Occurred Avery & DNA

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Avery & DNA Then They Treated Extract & Destroyed DNA Transformation Did NOT Occur DNA Was The Transforming Factor

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Avery & DNA Key Concept Avery and other scientists discovered that DNA stores and transmits the genetic information from one generation of an organism to the next generation.

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Hershey-Chase Experiment Studied Virus Particles, Especially BacteriophagesStudied Virus Particles, Especially Bacteriophages Martha Chase & Alfred Hershey

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT BacteriophagesBacteriophages –Composed of DNA or RNA –and a Protein Coat –Figured Whichever Part Entered The Bacteria – Carried The Genes Used Radioactive MarkersUsed Radioactive Markers Hershey-Chase Experiment

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Radioactive Markers Grew Viruses In Cultures ContainingGrew Viruses In Cultures Containing –Radioactive Phosphorus ( 32 P ) and and –Radioactive Sulfur ( 35 S ) Proteins Contain No Phosphorous DNA Contains No Sulfur

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Radioactive Markers Therefore: If The Interior Of The Bacteria Contained : ( 32 P ) Then DNA Contained Genes ( 35 S ) Then Protein Contained Genes Nearly All The Bacteria Contained ( 32 P ) Therefore DNA Contained Genes

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Hershey-Chase

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Hershey - Chase Key Concept: Hershey and Chase concluded that the genetic material of the bacteriophage was: DNA, not Protein.

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT The Structure of DNA Scientists still didn’t know:Scientists still didn’t know: –How information was carried between generations –How genes were structured –How genes were copied

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT The Structure of DNA DNA is a long Molecule of repeating nucleotidesDNA is a long Molecule of repeating nucleotides Each nucleotide has 3 parts:Each nucleotide has 3 parts: –5 Carbon Sugar (Deoxyribose) –1 Phosphate Group –1 Nitrogenous Base

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT The Structure of DNA There are 4 Nitrogenous Bases in DNAThere are 4 Nitrogenous Bases in DNA The 4 Bases fit into two groups or types:The 4 Bases fit into two groups or types: –Group 1 Purines AdenineAdenine GuanineGuanine –Group 2 Pyrimidines CytosineCytosine ThymineThymine

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Purines Pyrimidines

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT DNA Backbone Sugar & Phosphate Groups Nitrogenous Bases Stick Out & Join Sideways The Structure of DNA

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT The Structure of DNA Chargaffs Rules –Discovered That Certain Nucleotides Were Always Present In The Same Percentages: –Adenine & Thymine –Guanine & Cytosine –% In Each Species Different –Nobody Knew Why

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT The Structure of DNA X-Ray DiffractionX-Ray Diffraction –Early 1950’s –Rosalind Franklin Rosalind FranklinRosalind Franklin –Doesn’t Show Structure But Provides Clues DNA Twisted In CoilsDNA Twisted In Coils Two StrandsTwo Strands Nitrogenous Base In CenterNitrogenous Base In Center

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Photo 51

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT The Double Helix Watson & CrickWatson & Crick –Building 3 Dimensional Models –1953 Saw Franklins X-ray Work –Immediately Recognized What The Structure Had To Be: The Double Helix The Double Helix

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Watson & Crick Key Concept: Watson & Crick’s Model of DNA was a Double Helix, in which Two (2) Strands were wound around each other.

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Double Helix

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Watson & Crick Discovered The Double HelixDiscovered The Double Helix Held Together By Hydrogen Bonds Between The Nitrogenous BasesHeld Together By Hydrogen Bonds Between The Nitrogenous Bases Base PairingBase Pairing A:T and G:C Explained Chargaff’s Rule