chp 9: identification of dna as the genetic material

Question 1

frederick griffith performed experiments with

Answer 1

streptococcus pneumoniae

Question 1

in 1923

Answer 1

DNA was localized to chromosomes and made a candidate for the hereditary material
- however, both proteins and RNA are also found in chromosomes

Question 2

S. pneumoniae comes in two strains

Answer 2

1) Smooth
2) Rough

Question 3

Smooth streptococcus

Answer 3

secrete a polysaccharide capsule
- protects bacterium from the immune system of animals
- produce smooth colonies on solid media

Question 4

Rough streptococcus

Answer 4

• unable to secrete a capsule
• produce colonies with a rough appearance

Question 5

in 1925

Answer 5

Griffith conducted experiments using two strains of S. pneumoniae: type IIIS and type IIR

Question 6

1) inject mouse with live type IIIS bacteria

Answer 6

• mouse died
• type IIIS bacteria recovered from the mouse’s blood

Question 7

2) Inject mouse with live type IIR bacteria

Answer 7

• mouse survived
• no living bacteria isolated from the mouse’s blood

Question 8

3) inject mouse with heat-killed type IIIS bacteria

Answer 8

• mouse survived
• no living bacteria isolated from the mouse’s blood

Question 9

4) inject mouse with live type IIR + heat-killed type IIIS cells

Answer 9

• mouse died
• type IIIS bacteria recovered from the mouse’s blood

Question 10

transformation

Answer 10

Griffith concluded that something from the dead type IIIS bacteria was transforming type IIR bacteria into type IIIS

Question 11

transformation principle

Answer 11

the substance that allowed type IIR to transform into type IIIS

Question 12

the formation of the capsule is guided by

Answer 12

the bacteria’s genetic material