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DNA Section 12–1. This section tells about the experiments that helped scientists discover the relationship between genes and DNA. It also describes the.

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Presentation on theme: "DNA Section 12–1. This section tells about the experiments that helped scientists discover the relationship between genes and DNA. It also describes the."— Presentation transcript:

1 DNA Section 12–1

2 This section tells about the experiments that helped scientists discover the relationship between genes and DNA. It also describes the chemical structure of the DNA molecule. This section tells about the experiments that helped scientists discover the relationship between genes and DNA. It also describes the chemical structure of the DNA molecule.

3 Griffith and Transformation What did Frederick Griffith want to learn about bacteria? What did Frederick Griffith want to learn about bacteria? He wanted to learn how certain types of bacteria produce pneumonia He wanted to learn how certain types of bacteria produce pneumonia

4 The strain of bacteria that caused pneumonia grew into_________ colonies on culture plates; harmless bacteria produced colonies with edges. The strain of bacteria that caused pneumonia grew into_________ colonies on culture plates; harmless bacteria produced colonies with edges. Smooth Smooth

5 a. Mice injected with bacteria from smooth colonies died. a. Mice injected with bacteria from smooth colonies died. d. Mice injected with a mixture of bacteria from heat-killed smooth colonies and live rough colonies died. d. Mice injected with a mixture of bacteria from heat-killed smooth colonies and live rough colonies died.

6 What result from Griffith’s experiment suggested that the cause of pneumonia was not a chemical poison released by the disease-causing bacteria? What result from Griffith’s experiment suggested that the cause of pneumonia was not a chemical poison released by the disease-causing bacteria? The mice survived after being injected with heat-killed disease-causing bacteria. The mice survived after being injected with heat-killed disease-causing bacteria.

7 What is transformation? What is transformation? It is the process by which one strain of bacteria changes into another. It is the process by which one strain of bacteria changes into another.

8 What hypothesis did Griffith form from the results of his experiments? What hypothesis did Griffith form from the results of his experiments? Some factor,which might be a gene, was transferred from the heat-killed bacteria cells into the live cells. Some factor,which might be a gene, was transferred from the heat-killed bacteria cells into the live cells.

9 Avery and DNA Is the following sentence true or false? Is the following sentence true or false? Avery and his colleagues thought that the molecule required in transformation might also be the molecule of the gene. Avery and his colleagues thought that the molecule required in transformation might also be the molecule of the gene. True True

10 Avery and DNA Avery and DNA Briefly describe how Avery and his group determined which molecule was most important for transformation? Briefly describe how Avery and his group determined which molecule was most important for transformation? They treated the extract of heat-killed bacteria with enzymes that destroyed proteins, lipids, carbohydrates, and other molecules, including RNA and DNA. They treated the extract of heat-killed bacteria with enzymes that destroyed proteins, lipids, carbohydrates, and other molecules, including RNA and DNA.

11 Avery and DNA Avery and DNA Briefly describe how Avery and his group determined which molecule was most important for transformation? Briefly describe how Avery and his group determined which molecule was most important for transformation? They treated the extract of heat-killed bacteria with enzymes that destroyed proteins, lipids, carbohydrates, and other molecules, including RNA and DNA. They treated the extract of heat-killed bacteria with enzymes that destroyed proteins, lipids, carbohydrates, and other molecules, including RNA and DNA.

12 Avery and DNA Avery and DNA Briefly describe how Avery and his group determined which molecule was most important for transformation? Briefly describe how Avery and his group determined which molecule was most important for transformation? They treated the extract of heat-killed bacteria with enzymes that destroyed proteins, lipids, carbohydrates, and other molecules, including RNA and DNA. They treated the extract of heat-killed bacteria with enzymes that destroyed proteins, lipids, carbohydrates, and other molecules, including RNA and DNA.

13 Avery and DNA Transformation did not occur when _______was destroyed. Transformation did not occur when _______was destroyed. DNA DNA

14 Avery and DNA What was the conclusion from Avery’s experiments? What was the conclusion from Avery’s experiments? DNA was the transforming factor. DNA was the transforming factor.

15 The Hershey-Chase Experiment What is a bacteriophage? What is a bacteriophage? It is a virus that infects bacteria It is a virus that infects bacteria

16 The Hershey-Chase Experiment Parts that makes up a bacteriophage are: Parts that makes up a bacteriophage are: Protein Coat Protein Coat DNA core DNA core

17 The Hershey-Chase Experiment What happens when a bacteriophage infects a bacterial cell? What happens when a bacteriophage infects a bacterial cell? The bacteriophage injects its DNA into the cell. The viral genes act to produce many new bacteriophages, which burst out when the cell splits open. The bacteriophage injects its DNA into the cell. The viral genes act to produce many new bacteriophages, which burst out when the cell splits open.

18 The Hershey-Chase Experiment How would Hershey and Chase learn whether genes were made of protein or DNA? How would Hershey and Chase learn whether genes were made of protein or DNA? If they could determine which part of the virus entered the infected cell, they would learn whether genes were made of protein or DNA. If they could determine which part of the virus entered the infected cell, they would learn whether genes were made of protein or DNA.

19 The Hershey-Chase Experiment The molecule for which phosphorus-32 (32P) is used as a radioactive marker is___. The molecule for which phosphorus-32 (32P) is used as a radioactive marker is___. DNA DNA

20 The Hershey-Chase Experiment Is the following sentence true or false? Is the following sentence true or false? 35 S was found in the bacteria, it would mean that the viruses’ DNA had been injected into the bacteria___________. 35 S was found in the bacteria, it would mean that the viruses’ DNA had been injected into the bacteria___________. false false

21 The Hershey-Chase Experiment What results did Hershey and Chase observe? What results did Hershey and Chase observe? Nearly all of the radioactivity in the bacteria was from phosphorus, the marker found in DNA. Nearly all of the radioactivity in the bacteria was from phosphorus, the marker found in DNA.

22 The Hershey-Chase Experiment Hershey and Chase concluded that the genetic material of the bacteriophage was_____. Hershey and Chase concluded that the genetic material of the bacteriophage was_____. DNA DNA

23 The Components and Structure of DNA List the three critical things that genes were known to do. List the three critical things that genes were known to do. a. Genes had to carry information from one generation to the next. a. Genes had to carry information from one generation to the next. b. Genes had to determine the heritable characteristics of organisms. b. Genes had to determine the heritable characteristics of organisms. c. Genes had to be easily copied. c. Genes had to be easily copied.

24 The Components and Structure of DNA Adenine, guanine, cytosine, and thymine are four kinds of _______bases in DNA. Adenine, guanine, cytosine, and thymine are four kinds of _______bases in DNA. nitrogenous nitrogenous


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