Radioisotopes are frequently used to label molecules in a cell. The fate of atoms and molecules in a cell can then be followed. This process is the basis for the following question.


If Pseudomonas bacteria are supplied with radioactively labeled cytosine, after a 24-hour incubation period this cytosine would most likely be found in the cells’
a. Carbohydrates.
b. DNA.
c. Lipids.
d. Water.
e. Proteins.

What type of bond holds the following atoms together?

a. Li⁺ and Cl^- in LiCl

b. Carbon and oxygen atoms in methanol

c. Oxygen atoms in O₂

d. A hydrogen atom of one nucleotide to a nitrogen or oxygen atom of another nucleotide in:

Radioisotopes are frequently used to label molecules in a cell. The fate of atoms and molecules in a cell can then be followed. This process is the basis for the following question.

If E. coli were grown in a medium containing the radioactive isotope ³²P, the ³²P would be found in all of the following molecules of the cell except

a. ATP.

b. Carbohydrates.

c. DNA.

d. Plasma membrane.

e. Complex lipids.

What is a chemical element?

Diagram the electronic configuration of a carbon atom.

Radioisotopes are frequently used to label molecules in a cell. The fate of atoms and molecules in a cell can then be followed. This process is the basis for the following question.

Assume E. coli bacteria are grown in a nutrient medium containing the radioisotope ¹⁶N. After a 48-hour incubation period, the ¹⁶N would most likely be found in the E. coli’s

a. Carbohydrates.

b. Lipids.

c. Proteins.

d. Water.

e. None of the above