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GOB Chemistry: Proteins and Amino Acids

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Terms in this set (20)

  • What is biochemistry?

    Biochemistry is the study of the chemistry of life, focusing on all chemical reactions in living organisms.

  • What are the four classes of biomacromolecules in the human body?

    The four classes are proteins, lipids, carbohydrates, and nucleic acids.

  • What roles do proteins play in the body?

    Proteins act as enzymes (biological catalysts), hormones, storage, transport, structural, protective, and contractile proteins.

  • What is the general structure of an amino acid?

    An amino acid has a central alpha carbon bonded to an amine group, a carboxylic acid group, a hydrogen atom, and a variable side chain (R group).

  • What is a chiral carbon?

    A chiral carbon is a carbon atom bonded to four different groups, resulting in non-superimposable mirror images called stereoisomers.

  • Name the types of isomers relevant to amino acids.

    Isomers include constitutional isomers (different bonding order) and stereoisomers (same bonding order but different spatial arrangement), including enantiomers (mirror images) and diastereoisomers (not mirror images).

  • How are amino acids classified based on their side chains?

    Amino acids are classified as nonpolar, neutral polar, acidic, or basic based on the chemical properties of their side chains.

  • What are zwitterions in amino acids?

    Zwitterions are amino acids with both positive (amine) and negative (carboxylate) charges simultaneously, typically at physiological pH (~7).

  • Which amino acid side chains are charged at physiological pH?

    Acidic side chains carry a negative charge, and basic side chains carry a positive charge at pH 7.

  • What is the primary structure of a protein?

    The primary structure is the linear sequence of amino acids linked by peptide bonds, written from the N-terminus to the C-terminus.

  • Why are glycine, proline, and cysteine considered shape-determining amino acids?

    Glycine is flexible due to its small side chain, proline introduces rigidity due to its cyclic structure, and cysteine forms disulfide bonds stabilizing protein structure.

  • What are the main types of secondary structures in proteins?

    The main secondary structures are the alpha-helix and the beta-pleated sheet, stabilized by hydrogen bonds between backbone amide groups.

  • What interactions stabilize protein structures at different levels?

    Primary: covalent peptide bonds; Secondary: hydrogen bonds; Tertiary and Quaternary: hydrophobic interactions, hydrogen bonds, ionic bonds (salt bridges), and disulfide bonds.

  • What is the hydrophobic effect in protein folding?

    The hydrophobic effect causes nonpolar side chains to cluster away from water, driving protein folding and stabilizing tertiary structure.

  • How is an alpha-helix stabilized?

    An alpha-helix is stabilized by hydrogen bonds between the amide hydrogen of one amino acid and the carbonyl oxygen four residues earlier.

  • How are beta-pleated sheets stabilized?

    Beta-sheets are stabilized by hydrogen bonds between amide groups on adjacent beta-strands, which can be parallel or antiparallel.

  • What is a peptide bond?

    A peptide bond is a covalent amide bond formed between the carboxyl group of one amino acid and the amine group of another, releasing water.

  • What is the role of disulfide bonds in proteins?

    Disulfide bonds form covalent links between cysteine residues, stabilizing tertiary and quaternary protein structures.

  • Which amino acid side chains prefer hydrophobic environments?

    Nonpolar amino acids prefer hydrophobic environments and tend to be buried inside protein structures away from water.

  • What is the significance of protein quaternary structure?

    Quaternary structure refers to the assembly of multiple folded protein chains (subunits) into a functional complex, sometimes stabilized by disulfide bonds.