Amino Acids, Proteins & Enzymes Quiz

What two functional groups are found in all amino acids?

Answer explanation

All amino acids contain two functional groups: an amino group (-NH2) and a carboxyl group (-COOH). These groups are essential for the structure and function of amino acids in proteins.

What is a zwitterion and when does it form?

Answer explanation

A zwitterion is a molecule that has both positive and negative charges but is overall neutral. It forms when an amino acid, for example, has a protonated amine group and a deprotonated carboxyl group, typically at physiological pH.

How does the R group affect amino acid properties?

Answer explanation

The R group, or side chain, determines the unique characteristics of each amino acid, influencing properties like polarity, charge, and size, which affect protein structure and function.

What type of reaction forms a peptide bond?

Answer explanation

A peptide bond is formed through a condensation reaction, where two amino acids join together, releasing a molecule of water. This process is essential in protein synthesis.

What is the difference between a dipeptide and a polypeptide?

Answer explanation

A dipeptide consists of two amino acids linked by a peptide bond, while a polypeptide is a longer chain of amino acids, typically containing more than 10. Thus, the main difference is the number of amino acids in the chain.

What reaction breaks a peptide bond?

Answer explanation

Hydrolysis is the reaction that breaks peptide bonds by adding water, which cleaves the bond between amino acids, resulting in the formation of free amino acids.

What type of bonding stabilizes secondary structure?

Answer explanation

Hydrogen bonding stabilizes secondary structures in proteins, such as alpha helices and beta sheets, by forming interactions between the backbone amide and carbonyl groups, contributing to the overall stability of the protein's shape.

What interactions contribute to tertiary structure?

Answer explanation

Tertiary structure is stabilized by various interactions, including hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals forces, which collectively determine the three-dimensional shape of a protein.

What is an example of a protein with quaternary structure?

Answer explanation

Hemoglobin is a classic example of a protein with quaternary structure, as it consists of four polypeptide chains that work together to transport oxygen in the blood.

How do enzymes speed up reactions?

Answer explanation

Enzymes speed up reactions by lowering the activation energy required for the reaction to occur, allowing substrates to convert into products more quickly and efficiently.