a. It is possible to bathe a cell in radioactively tagged amino acids and then later to detect photographically the location of radiation, and therefore the amino acids in the cell. Why would you suggest using radioactive sulfur (i.e., the amino acids cysteine and methionine contain sulfer) rather than radioactive carbon?Answer
b. An investigator uses the procdure outlined in question a to support the belief that proteins move from the cytoplasm into the nucleus. If so, where will radiation first appear, and where will it subsequently appear in the cell?Answer
c. An investigator uses this same procedure to support the belief that proteins move from the rough ER to secretory vesicles. Where will the radiation first appear, and where will it subsequently appear in the cell?Answer
2. A microtubular spindle apparatus appears in plant and animal cells at the time of cell division.
a. Why does this suggest that centrioles are not necessary to the formation of the spindle apparatus?Answer
b. What evidence is there to suggest centrioles are necessary to microtubule organization in animal cells?Answer
c. In animal cells, each newly formed cell receives a pair of centrioles. Why might centrioles be necessary to animal cells but not to most plant cells?Answer