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. cerevisiae's A) water. B) nucleic acids. C) proteins. D) carbohydrates. E) lipids.

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Sulfur-35 is a radioisotope that labels sulfur-containing compounds. In cells, sulfur is primarily found in amino acids like cysteine and methionine, which are components of proteins. Therefore, the radioisotope would most likely be found in the proteins of Saccharomyces cerevisiae.

Radioisotopes Are Frequently Used to Label Molecules in a Cell