Proteins and Amino Acids Quiz

Proteins

• Proteins are made of amino acids linked together by peptide bonds to form one or more polypeptides
• Each polypeptide is folded and coiled into a unique conformation
• Proteins serve a wide variety of biological functions: catalysts (enzymes), transport, structural support, movement, messaging and signaling, defense against infection
• There are predicted to be tens of thousands of different types of proteins
• There are 20 different amino acids

Amino Acids

• The monomer of proteins is the amino acid
• Each amino acid has a central carbon backbone that has an amino group, a carboxyl group, and an R group
• The R group is variable and determines the amino acid’s properties

Polypeptides

• A polypeptide is a polymer of amino acids linked by peptide bonds
• Peptide bonds are formed via a condensation reaction
• Polypeptides have a C-terminus (carboxyl end) and an N-terminus (amino end)

Protein Structure

• Four main structural levels of proteins:
  • Primary structure: the linear sequence of amino acids in a polypeptide chain
  • Secondary structure: regular, repeating patterns of folding of the polypeptide chain, such as alpha-helices and beta-sheets
  • Tertiary structure: the three-dimensional shape of a single polypeptide chain, including interactions such as hydrogen bonds, hydrophobic interactions, ionic bonds, and disulfide bridges
  • Quaternary structure: the arrangement of multiple polypeptide chains (subunits) in a protein complex
• Proteins can be fibrous (elongated and fibrous) or globular (compact and spherical)
  • Fibrous proteins often serve structural roles in the body
    • Ex. keratin in hair and nails, collagen in tendons and ligaments
  • Globular proteins are often involved in enzymatic activity, transport, signaling, and other biological functions
    • Ex. antibodies, enzymes

Protein Folding

• The final shape of a protein is determined by its amino acid sequence and interactions between R groups
• Forces that stabilize secondary, tertiary, and quaternary structures:
  • Hydrogen bonding between backbone atoms
  • Hydrophobic interactions between nonpolar R groups
  • Ionic interactions between charged R groups
  • Disulfide bridges between cysteine residues
• Misfolding of proteins can lead to disease
  • Prion diseases, Alzheimer's disease, and Parkinson's disease

Test your knowledge on the structure and functions of proteins, amino acids, and polypeptides. This quiz covers key concepts, including peptide bonds, the unique structures of proteins, and the role of amino acids. Perfect for biology students looking to solidify their understanding of these essential biomolecules.