Chapter 13.1.1 (Exam 3) Experiments

Question 1

What were the three experiments involved in proving DNA was the genetic material of organisms?

Answer 1

Griffith’s transforming principle

Avery, MacLeod and McCarty’s experiment

The Hershey-Chase experiment

Question 2

What was Griffith’s experimental design?

Answer 2

He injected mice with 4 strains of bacteria to see which would live and die

One living virulent (S) strain
One living nonvirulent (R) strain
One dead virulent (S) strain
One living nonvirulent (R) strain mixed with dead virulent (S) strain

Question 3

What happened to the mice in Griffith’s experiment after being injected with each strain?

Answer 3

One living virulent (S) strain - Mouse died

One living nonvirulent (R) strain - Mouse lives

One dead virulent (S) strain - Mouse lives

One living nonvirulent (R) strain mixed with dead virulent (S) strain - Mouse dies

Question 4

What did the result of Griffith’s experiment show?

Answer 4

There was some genetic information present in the virulent (S) cells that passed on to the nonvirulent (R) cells that transformed them into virulent cells

Question 5

Describe the experimental design of Avery, MacLeod, and McCarty.

Answer 5

Dead virulent (S) strains of bacteria were mixed with the living nonvirulent (R) strain bacteria in flasks

Three separate flasks were treated with RNase, protease, and DNase

Question 6

What happened in the Avery, MacLeod, and McCarty experiment?

Answer 6

The flask that DNase was added to was the only one that contained only nonvirulent (R) strain bacteria

The other two flasks (treated with RNase and protease) contained virulent (S) strain bacteria, indicating that the genetic information of the bacteria had still survived

These results indicated that DNA was the genetic information

Question 7

Describe the experimental design of the Hershey-Chase experiment.

Answer 7

A bacteriophage known as the T2 virus was used to determine whether DNA or protein was the genetic information

The proteins and DNA present within the bacteriophage were labeled with isotopes

This allowed them to determine which was the genetic information, by seeing what the bacteria was tagged with

Question 8

What was the protein tagged with in the Hershey-Chase experiment? The DNA?

Answer 8

³⁵S to label the protein

³²P to label the DNA

Question 9

In the Hershey-Chase experiment, what were the bacterial cells labeled with? What did that indicate?

Answer 9

After infection, bacterial cells and viral remains were separated—The bacterial cells were labeled with ³²P, indicating that DNA had entered the cells