Amino Acids, Proteins & Enzymes Quiz

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.