Radioisotopes are frequently used to label molecules in a cell. The fate of atoms and molecules in a cell can then be followed. Assume Saccharomyces cerevisiae is grown in a nutrient medium containing the radioisotope 35S. After a 48-hour incubation, the 35S would most likely be found in the S. cerevisiaeʹs
A) proteins.
B) nucleic acids.
C) lipids.
D) carbohydrates.
E) water.

Question

Quizplus · Accepted Answer

35S is a radioactive isotope of sulfur, which is primarily found in the amino acids cysteine and methionine. These amino acids are building blocks of proteins, so 35S would most likely be incorporated into proteins.

Radioisotopes Are Frequently Used to Label Molecules in a Cell