Proteins

• What are proteins made from?

  Amino acids
• What is formed when two amino acids join together?

  Dipeptide
• What is formed when more than two amino acids join together?

  Polypeptide
• What is the basic unit of proteins?


  Amino acid
• What are the types of peptides based on amino acid count?

  • Monomer: one amino acid
  • Dipeptide: two amino acids
  • Polypeptide: more than two amino acids
• What is the general structure of an amino acid?

  Carboxyl group, amino group, and R group
• What is the exception to the R group rule in amino acids?

  Glycine
• How are amino acids linked together?

  By condensation reactions
• What is released during the formation of dipeptides and polypeptides?

  A molecule of water
• What are the bonds formed between amino acids called?

  Peptide bonds
• What happens during hydrolysis of dipeptides and polypeptides?

  They are broken down
• What are the four levels of protein structure?

  1. Primary structure: sequence of amino acids
  2. Secondary structure: alpha helix or beta pleated sheet
  3. Tertiary structure: 3D structure of a single chain
  4. Quaternary structure: assembly of multiple chains
• What is the primary structure of a protein?

  The sequence of amino acids
• What forms the secondary structure of a protein?

  Hydrogen bonds between amino acids
• What are the two common forms of secondary structure?

  Alpha helix and beta pleated sheet
• What is the tertiary structure of a protein?

  The further coiling and folding of the chain
• What types of bonds are involved in tertiary structure?

  Hydrogen bonds and ionic bonds
• What forms disulfide bridges in proteins?

  Two cysteine molecules coming close together
• What is the quaternary structure of a protein?

  Assembly of multiple polypeptide chains
• What is an example of a protein with quaternary structure?

  Hemoglobin
• How does a protein's shape relate to its function?

  Shape determines its specific function
• What are examples of different types of proteins and their functions?

  • Enzymes: metabolic roles, often spherical
  • Antibodies: immune response, variable regions
  • Transport proteins: channel proteins in membranes
  • Structural proteins: strong, e.g., keratin and collagen
• What is the biuret test used for?

  To test for proteins
• What does a blue solution indicate in the biuret test?

  No protein is present
• What is the first step in the biuret test?

  Add sodium hydroxide solution
• What happens if protein is present in the biuret test?

  The solution turns purple
• What are the results of the biuret test?

  • Positive result: solution turns purple
  • Negative result: solution stays blue
• What is the role of enzymes in metabolism?

  They help break down large food molecules
• What is the structure of antibodies?

  Two light and two heavy polypeptide chains
• What is the function of transport proteins?

  Transport molecules across membranes
• What are structural proteins like keratin and collagen used for?

  Provide physical strength and support