Unit 8.1

Question 1

Explain the process of Griffith’s Experiment.

Answer 1

Griffith’s experiment in 1928 demonstrated bacterial transformation using two strains of Streptococcus pneumoniae: the virulent S strain with a protective coat and the harmless R strain without it. He injected mice with various combinations: live S strain killed the mice, live R strain and heat-killed S strain did not, but a mixture of heat-killed S strain and live R strain unexpectedly killed the mice. He found live S strain bacteria in their blood, concluding that a “transforming principle” from the dead S strain had converted the harmless R strain into a virulent form.

Question 2

What did Griffith’s Experiment prove?

Answer 2

that bacteria are capable of transferring genetic information through a process known as transformation

Question 3

Explain the process of the Avery Experiment.

Answer 3

The Avery, MacLeod, and McCarty experiment in 1944 built on Griffith’s work to identify DNA as the “transforming principle.” They treated heat-killed S strain Streptococcus pneumoniae with enzymes that destroyed proteins, RNA, or DNA before mixing it with live R strain. Transformation still occurred when proteins and RNA were destroyed, but not when DNA was destroyed.

Question 4

What did the Avery Experiment prove?

Answer 4

that DNA is the “transforming principle” responsible for carrying genetic information

Question 5

Explain the process of the Hershey & Chase Experiment.

Answer 5

The Hershey and Chase experiment in 1952 confirmed that DNA is the genetic material. They used bacteriophages (viruses that infect bacteria) labeled with radioactive isotopes: sulfur-35 to mark proteins and phosphorus-32 to mark DNA. After the phages infected bacteria, they separated the viral parts from the bacterial cells using a blender and centrifuge.

Question 6

What did the Hershey & Chase Experiment prove?

Answer 6

DNA, not protein, is the genetic material that carries genetic information and is passed on from one generation to the next

Question 7

What are the two pairs of DNA bases?

Answer 7

A and T, G and C

Question 8

If G = 14%, what do the other three bases equal?

Answer 8

G = 14%
C = 14%
A = 36%
T = 36%

Question 9

In the diagram, what is C?

Answer 9

deoxyribose sugar

Question 10

In the diagram, what is B?

Answer 10

phosphate group