Presentation is loading. Please wait.

Presentation is loading. Please wait.

8.2 Structure of DNA Set up Cornell Notes on pg. 3 Topic: 8.1 Identifying DNA as the Genetic Material Essential Question: Summarize: Why was bacteriophage.

Similar presentations


Presentation on theme: "8.2 Structure of DNA Set up Cornell Notes on pg. 3 Topic: 8.1 Identifying DNA as the Genetic Material Essential Question: Summarize: Why was bacteriophage."— Presentation transcript:

1 8.2 Structure of DNA Set up Cornell Notes on pg. 3 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

2 8.1 Identifying DNA as the Genetic Material KEY CONCEPT DNA was identified as the genetic material through a series of experiments.

3 8.1 Identifying DNA as the Genetic Material Frederick Griffith (1928) –Microbiologist studying the bacterium that causes pneumonia to create a vaccine »He studied two types oS- smooth- Pneumonia + death oR- rough- Pneumonia + recovery

4 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? +

5 8.1 Identifying DNA as the Genetic Material Griffith injected the two types of bacteria into mice 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

6 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!

7 8.1 Identifying DNA as the Genetic Material When Griffith heat-killed the S bacteria and injected it into the mice, they were unaffected (healthy and alive). Hypothesize what happened when Griffith heat-killed the S bacteria and injected it into the mice.

8 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?

9 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?

10 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!

11 8.1 Identifying DNA as the Genetic Material Table Talk Remember: –Live R= live mouse –Heat-killed S= 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.

12 8.1 Identifying DNA as the Genetic Material A “transforming material” passed from dead S bacteria to live R bacteria, making them deadly.

13 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.

14 8.1 Identifying DNA as the Genetic Material 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.

15 8.1 Identifying DNA as the Genetic Material Avery’s Experiments (DEMO) Broke down the Heat-killed S bacteria into its components –Carbohydrates –Lipids –Proteins –DNA –RNA He then added Live R bacteria What should we expect to happen to each animal? Rabbit 1: Carbs T-Rex 2: Lipids Rabbit 3: Proteins Snail 4: DNA Elephant 5: RNA

16 8.1 Identifying DNA as the Genetic Material Avery’s Experiments Cont’ (DEMO #2) 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 What should we expect to happen to each animal? Rabbit 1: Carb destroying enzyme T-Rex 2: Lipid destroying enzyme Rabbit 3: Protein destroying enzyme Snail 4: DNA destroying enzyme Elephant 5: RNA destroying enzyme

17 8.1 Identifying DNA as the Genetic Material –Transformation ONLY stopped when an enzyme was added that destroyed DNA!!!

18 8.1 Identifying DNA as the Genetic Material He thought DNA was the transforming principle, but more proof was needed…

19 8.1 Identifying DNA as the Genetic Material Hershey and Chase studied viruses that infect bacteria, or bacteriophages. (1952)

20 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! –They tagged viral proteins with radioactive sulfur They tagged viral DNA with radioactive phosphorus

21 8.1 Identifying DNA as the Genetic Material

22 Biologix DNA Video


Download ppt "8.2 Structure of DNA Set up Cornell Notes on pg. 3 Topic: 8.1 Identifying DNA as the Genetic Material Essential Question: Summarize: Why was bacteriophage."

Similar presentations


Ads by Google