Homework SourseUnderstanding the structural and molecular interactions that
Understanding the structural and molecular interactions that induce shape and function for a protein has been an obstacle for some of your students. You decide to plan a lesson to introduce them to the basic amino acid structure and then use that concept to introduce the different levels of protein structure. To reinforce your lesson on amino acids, you need to aid the students in understanding that most naturally occurring amino acids have a shared base structure. Each amino acid has an amine group, an alpha-carbon (or central carbon), an R-side group, and a carboxyl group. The R-side group is what gives each amino acid its distinctive characteristics--for example, whether the amino acid will be acidic or basic, hydrophilic or hydrophobic, or charged.
Choose the statement that does NOT pertain to amino acids.
| a. All amino acids must contain a nitrogen-based molecule and a carboxylic acid. |
| b. Amino acids always contain a sulfur atom in their R-side group. |
| c. The groups composing an amino acid are located around a central alpha-carbon. |
| d. The R-side group will determine the overall chemical properties of an individual amino acid. |
Solution
ANSWER: Option B: The amino acids have central carbon atom to which amino and carboxylic groups are bonded along with one H atom and one R group. The R group determines the chemical properties of the amino acids. The R group may or may not have sulfur atoms. Methionine and cysteine are the only two amino acids out of 20 standard amino acids that have sulfur atoms in their side chains. Correct answer is B.
