Summarize Fredrick Griffith’s, Oswald Avery’s, and others’ experimental search for a treatment for pneumonia. What will be an ideal response?
ANSWER: Griffith discovered that the ability to cause pneumonia is a genetic trait that can be passed
from one strain of bacteria to another. Griffith isolated two strains of Streptococcus
pneumoniae. One strain was surrounded by a capsule that allowed it to evade the immune
system and cause pneumonia. Griffith called this strain S. The other strain was not surrounded by a capsule and did not cause pneumonia. Griffith called this strain R. He found
that mice injected with strain R do not develop pneumonia and mice injected with strain S
develop pneumonia and die. Furthermore, when the S strain cells are killed by heat treatment
before injection, mice do not develop pneumonia. Griffith discovered that when mice are
injected with a mixture of heat-killed S cells and live R cells, they develop pneumonia and
die. Avery concluded that DNA from the dead S cells was responsible for transforming the R
cells into S cells.
You might also like to view...
Match the following items with the correct phrases.
_______1. A protein that plays a role in DNA replication. _______2. The end product of transcription. _______3. A protein that plays a role in transcription. _______4. The location of codons. _______5. The location of anticodons. _______6. An integral part of ribosomes, whether or not they are participating in protein synthesis. _______7. Produced in the nucleolus of eucaryotic cells. _______8. The molecule responsible for “activating” amino acids, thus enabling them to be added to the growing polypeptide chain. a. DNA polymerase b. RNA polymerase c. mRNA d. rRNA e. tRNA
Which layer(s) of the digestive tract in mammals directly contacts the lumen?
a. mucosa b. muscularis c. submucosa d. serosa e. serosa and muscularis
In somatic hypermutation, the mutation of immunoglobulin genes occurs at much higher rates than the mutation rates observed in other genes
Indicate whether the statement is true or false.
In an isotonic contraction of a skeletal muscle,
(a) the tension in the muscle increases. (b) movement occurs. (c) no movement occurs. (d) both a and c occur.