Selenium can substitute for sulfur in the amino acid cysteine to make the amino acid selenocysteine because ________
A)sulfur and selenium both begin with s.
B)their atomic symbols are similar.
C)both have about the same atomic radius.
D)both have the same valence electron configuration.
E)both have about the same ionization potential.

Question

Quizplus · Accepted Answer

Cysteine and selenocysteine have the same chemical structure except that selenium replaces sulfur, which means they have the same valence electron configuration. This similarity allows selenium to substitute for sulfur in cysteine to form selenocysteine.

Selenium Can Substitute for Sulfur in the Amino Acid Cysteine