8.2 Structure of DNA Set up Cornell Notes on pg. 91 Topic: 8.1 Identifying DNA as the Genetic Material Essential Question: Summarize: Why was bacteriophage an excellent choice for research to determine whether genes are made of DNA or proteins? 2.1 Atoms, Ions, and Molecules Summarize: Why was bacteriophage an excellent choice for research to determine whether genes are made of DNA or proteins? 8.1 Identifying DNA as the Genetic Material Key Concept:DNA was identified as the genetic material through a series of experiments

8.2 Structure of DNA Pg 90 Summarize: Avery Demo #1 Summarize: Avery Demo #2

8.1 Identifying DNA as the Genetic Material KEY CONCEPT DNA was identified as the genetic material through a series of experiments.

8.1 Identifying DNA as the Genetic Material Pneumonia Pneumonia is an infection in one or both of your lungs. Can be caused by bacteria/viruses OUR FOCUS: Streptococcus pneumoniae (bacteria) When the germs that cause pneumonia reach your lungs, the lungs' air sacs (alveoli) become inflamed and fill up with fluid. This causes the symptoms of pneumonia, such as a cough, fever, chills, and trouble breathing. When you have pneumonia, oxygen may have trouble reaching your blood. If there is too little oxygen in your blood, your body cells can't work properly. Because of this and the infection spreading through the body, pneumonia can cause death.

8.1 Identifying DNA as the Genetic Material Pneumonia was a serious cause of death in the wake of the post-WWI Spanish influenza pandemic Frederick Griffith (1928) Microbiologist studying the bacterium that causes pneumonia to create a vaccine –He studied two types: S strain (smooth): which was virulent and encapsulated in a coat of sugar molecules R strain (rough): was not virulent and was non-encapsulated

8.1 Identifying DNA as the Genetic Material Griffith injected the two types of bacteria into mice Hypothesize what should Griffith expect to find when he injects the S (encapsulated) bacteria into the mice? What about the R (non-encapsulated) bacteria? Griffith’s Experiments Unaffected

8.1 Identifying DNA as the Genetic Material Hypothesize why only the S (encapsulated) strain would be deadly. The capsule protects the bacteria from the immune system!

8.1 Identifying DNA as the Genetic Material Hypothesize what would Griffith expect to find if he combined the live S bacteria with live R bacteria? + Live S + Live R= Rationale:

8.1 Identifying DNA as the Genetic Material Hypothesize what happened when Griffith heat-killed the S bacteria and injected it into the mice. Heat-killed S= Rationale: Unaffected

8.1 Identifying DNA as the Genetic Material Hypothesize what Griffith expect to find if he combined the dead S bacteria with live R bacteria? Heat-killed S + Live R= Rationale:

8.1 Identifying DNA as the Genetic Material When Griffith injected mice with a combination of heat- killed S bacteria and R bacteria the mouse died!!! What do you think he found when he took a blood test of the dead mouse?

8.1 Identifying DNA as the Genetic Material When he did a blood test on the dead mouse he found live S bacteria in the dead mice!

8.1 Identifying DNA as the Genetic Material Table Talk Remember: –Live R= unaffected live mouse –Heat-killed S= unaffected live mouse –Live R + Heat-killed S= dead mouse Hypothesize with your table about what happened when the heat-killed S bacteria was combined with the R bacteria.

8.1 Identifying DNA as the Genetic Material Griffith hypothesized that a “transforming material” passed from dead S bacteria to live R bacteria, making them turn into deadly S bacteria. “Transformation” suggested that bacteria are capable of transferring genetic material from one bacteria to another

8.1 Identifying DNA as the Genetic Material Oswald Avery, a biologist, spent 10 years trying to figure out what Griffith had discovered (1944) He combined R bacteria with an extract made from S bacteria and observed R bacteria turning into S bacteria under a microscope.

8.1 Identifying DNA as the Genetic Material He wanted to know if it was DNA or protein that transformed harmless R bacteria into deadly S bacteria –tests showed DNA was present when proteins were not. –chemical makeup matched that of DNA.

8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO): TOP P. 90 Broke down the Heat-killed S bacteria into its components –DNA –Lipids –Carbohydrates –Proteins –RNA carbohydratescarbohydrates LipidsLipids ProteinsProteins DNADNA RNARNA

8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO): TOP P. 90

8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO): TOP P. 90

8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO): TOP P. 90

8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO): TOP P. 90

8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO): TOP P. 90

8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO): TOP P. 90 He then added Live R bacteria (dead S + Live R) What should we expect to happen to each animal? Pig: Carbs= T-Rex : Lipids= Owl: Proteins= Snail : DNA= Elephant : RNA=

8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO): TOP P. 90 What should we expect to happen to each animal? Pig: Carbs LIVE!!!! T-Rex 2: Lipids LIVE!!!! Owl: Proteins LIVE!!!! Snail 4: DNA DEAD!!!! Elephant 5: RNA LIVE!!!!

8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO): TOP P. 90 Summarize how Avery’s first experiment supports the theory that DNA is the “transforming principle”.

8.1 Identifying DNA as the Genetic Material carbohydratescarbohydrates LipidsLipids ProteinsProteins DNADNA RNARNA Avery’s Experiments Cont’ (DEMO #2) Bottom: P. 90 Even though this was good evidence that DNA was the genetic material, more evidence was needed. This time scientists decided to add enzymes that destroyed specific components of the Heat-killed S bacteria

8.1 Identifying DNA as the Genetic Material carbohydratescarbohydrates LipidsLipids ProteinsProteins DNADNA RNARNA Avery’s Experiments Cont’ (DEMO #2) Bottom: P. 90 This time scientists decided to add enzymes that destroyed specific components of the Heat-killed S bacteria DNA destroying enzyme

8.1 Identifying DNA as the Genetic Material carbohydratescarbohydrates LipidsLipids ProteinsProteins DNADNA RNARNA Avery’s Experiments Cont’ (DEMO #2) Bottom: P. 90 This time scientists decided to add enzymes that destroyed specific components of the Heat-killed S bacteria Lipid destroying enzyme

8.1 Identifying DNA as the Genetic Material carbohydratescarbohydrates LipidsLipids ProteinsProteins DNADNA RNARNA Avery’s Experiments Cont’ (DEMO #2) Bottom: P. 90 This time scientists decided to add enzymes that destroyed specific components of the Heat-killed S bacteria Carbohydrate destroying enzyme

8.1 Identifying DNA as the Genetic Material carbohydratescarbohydrates LipidsLipids ProteinsProteins DNADNA RNARNA Avery’s Experiments Cont’ (DEMO #2) Bottom: P. 90 This time scientists decided to add enzymes that destroyed specific components of the Heat-killed S bacteria Protein destroying enzyme

8.1 Identifying DNA as the Genetic Material carbohydratescarbohydrates LipidsLipids ProteinsProteins DNADNA RNARNA Avery’s Experiments Cont’ (DEMO #2) Bottom: P. 90 This time scientists decided to add enzymes that destroyed specific components of the Heat-killed S bacteria RNA destroying enzyme

8.1 Identifying DNA as the Genetic Material Avery’s Experiments Cont’ (DEMO #2) Bottom: P. 90 What should we expect to happen to each animal? Pig: Carb destroying enzyme= T-Rex : Lipid destroying enzyme= Owl: Protein destroying enzyme= Snail : DNA destroying enzyme= Elephant: RNA destroying enzyme=

8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO): Bottom P. 90 What should we expect to happen to each animal? Pig: Carbs DEAD!!!! T-Rex 2: Lipids DEAD!!!! Owl: Proteins DEAD!!!! Snail 4: DNA LIVE!!!! Elephant 5: RNA DEAD!!!!

8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO): Bottom P. 90 Summarize how Avery’s second experiment supports the theory that DNA is the “transforming principle”.

8.1 Identifying DNA as the Genetic Material –Transformation ONLY stopped when an enzyme was added that destroyed DNA!!!

8.1 Identifying DNA as the Genetic Material He thought DNA was the transforming principle, but more proof was needed…

8.1 Identifying DNA as the Genetic Material Hershey and Chase studied viruses that infect bacteria, or bacteriophages. (1952)

8.1 Identifying DNA as the Genetic Material They tagged viral proteins with radioactive sulfur Sulfur is found in protein, but NOT in DNA DNA They tagged viral DNA with radioactive phosphorus Phosphorus is found in DNA, but NOT in protein bacterium

8.1 Identifying DNA as the Genetic Material

bacterium When they examined the bacteria, they found no significant radioactivity This time radioactivity was clearly present in the bacteria!

8.1 Identifying DNA as the Genetic Material Tagged DNA was found inside the bacteria; tagged proteins were not. This confirmed that DNA was the genetic material!

8.1 Identifying DNA as the Genetic Material Biologix DNA Video (28m46s) Answer ALL questions