DNA DNA

Section 12–1Section 12–1

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

Griffith and Transformation Griffith and Transformation

What did Frederick Griffith want to What did Frederick Griffith want to learn about bacteria? learn about bacteria?

He wanted to learn how certain types He wanted to learn how certain types of bacteria produce pneumoniaof bacteria produce pneumonia

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

SmoothSmooth

a. a. Mice injected with bacteria from Mice injected with bacteria from smooth colonies died.smooth colonies died.

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

What result from Griffith’s experiment What result from Griffith’s experiment suggested that the cause of pneumonia suggested that the cause of pneumonia was not a chemical poison released by was not a chemical poison released by the disease-causing bacteria?the disease-causing bacteria?

The mice survived after being injected The mice survived after being injected with heat-killed disease-causing with heat-killed disease-causing bacteria.bacteria.

What is transformation? What is transformation?

It is the process by which one strain It is the process by which one strain of bacteria changes into another.of bacteria changes into another.

What hypothesis did Griffith form What hypothesis did Griffith form from the results of his experiments? from the results of his experiments?

Some factor,which might be a gene, Some factor,which might be a gene, was transferred from the heat-killed was transferred from the heat-killed bacteria cells into the live cells.bacteria cells into the live cells.

Avery and DNAAvery and DNA

Is the following sentence true or false? Is the following sentence true or false?

Avery and his colleagues thought that Avery and his colleagues thought that thethemolecule required in transformation molecule required in transformation might also be the molecule of the gene.might also be the molecule of the gene.

TrueTrue

Avery and DNAAvery and DNA

Briefly describe how Avery and his group Briefly describe how Avery and his group determined which molecule was most determined which molecule was most important for transformation?important for transformation?

They treated the extract of heat-killed They treated the extract of heat-killed bacteria with enzymes that destroyed bacteria with enzymes that destroyed proteins, lipids, carbohydrates, and other proteins, lipids, carbohydrates, and other molecules, including RNA and DNA.molecules, including RNA and DNA.

Avery and DNAAvery and DNA

Briefly describe how Avery and his group Briefly describe how Avery and his group determined which molecule was most determined which molecule was most important for transformation?important for transformation?

They treated the extract of heat-killed They treated the extract of heat-killed bacteria with enzymes that destroyed bacteria with enzymes that destroyed proteins, lipids, carbohydrates, and other proteins, lipids, carbohydrates, and other molecules, including RNA and DNA.molecules, including RNA and DNA.

Avery and DNAAvery and DNA

Briefly describe how Avery and his group Briefly describe how Avery and his group determined which molecule was most determined which molecule was most important for transformation?important for transformation?

They treated the extract of heat-killed They treated the extract of heat-killed bacteria with enzymes that destroyed bacteria with enzymes that destroyed proteins, lipids, carbohydrates, and other proteins, lipids, carbohydrates, and other molecules, including RNA and DNA.molecules, including RNA and DNA.

Avery and DNAAvery and DNA

Transformation did not occur when Transformation did not occur when _______was destroyed._______was destroyed.

DNA DNA

Avery and DNAAvery and DNA

What was the conclusion from What was the conclusion from Avery’s experiments?Avery’s experiments?

DNA was the transforming factor.DNA was the transforming factor.

The Hershey-Chase The Hershey-Chase ExperimentExperiment

What is a bacteriophage? What is a bacteriophage?

It is a virus that infects bacteriaIt is a virus that infects bacteria

The Hershey-Chase The Hershey-Chase ExperimentExperiment

Parts that makes up a bacteriophage Parts that makes up a bacteriophage are:are:

Protein CoatProtein Coat

DNA coreDNA core

The Hershey-Chase The Hershey-Chase ExperimentExperiment

What happens when a bacteriophage What happens when a bacteriophage infects a bacterial cell?infects a bacterial cell?

The bacteriophage injects its DNA The bacteriophage injects its DNA into the cell. The viral genes act to into the cell. The viral genes act to produce many new bacteriophages, produce many new bacteriophages, which burst out when the cell splits which burst out when the cell splits open.open.

The Hershey-Chase The Hershey-Chase ExperimentExperiment

How would Hershey and Chase learn How would Hershey and Chase learn whether genes were made of protein whether genes were made of protein or DNA?or DNA?

If they could determine which part of If they could determine which part of the virus entered the infected cell, the virus entered the infected cell, they would learn whether genes were they would learn whether genes were made of protein or DNA.made of protein or DNA.

The Hershey-Chase The Hershey-Chase ExperimentExperiment

The molecule for which phosphorus-The molecule for which phosphorus-32 (32P) is used as a radioactive 32 (32P) is used as a radioactive marker is___.marker is___.

DNADNA

The Hershey-Chase The Hershey-Chase ExperimentExperiment

Is the following sentence true or false?Is the following sentence true or false?

3535S was found in the bacteria, it would S was found in the bacteria, it would mean that the viruses’ DNA had been mean that the viruses’ DNA had been injected into the bacteria___________.injected into the bacteria___________.

falsefalse

The Hershey-Chase The Hershey-Chase ExperimentExperiment

What results did Hershey and Chase What results did Hershey and Chase observe?observe?

Nearly all of the radioactivity in the Nearly all of the radioactivity in the bacteria was from phosphorus, the bacteria was from phosphorus, the marker found in DNA.marker found in DNA.

The Hershey-Chase The Hershey-Chase ExperimentExperiment

Hershey and Chase concluded that Hershey and Chase concluded that the genetic material of the the genetic material of the bacteriophage was_____.bacteriophage was_____.

DNADNA

The Components and The Components and Structure of DNA Structure of DNA

List the three critical things that genes List the three critical things that genes were known to do.were known to do.

a. a. Genes had to carry information from Genes had to carry information from one generation to the next.one generation to the next.

b. b. Genes had to determine the heritable Genes had to determine the heritable characteristics of organisms.characteristics of organisms.

c. c. Genes had to be easily copied.Genes had to be easily copied.

The Components and The Components and Structure of DNAStructure of DNA

Adenine, guanine, cytosine, and Adenine, guanine, cytosine, and thymine are four kinds of thymine are four kinds of _______bases in DNA. _______bases in DNA.

nitrogenousnitrogenous