Proteins

• What are the two main types of proteins mentioned in the study material?

  Fibrous proteins and globular proteins
• What is the primary function of fibrous proteins?

  They provide structural support
• What is the primary function of globular proteins?

  They perform metabolic functions
• What is the monomer of proteins?

  Amino acids
• What are the components of an amino acid?

  Amine group, carboxyl group, hydrogen, and R group
• What is the R group in an amino acid?

  It is the variant group that differs among amino acids
• What is the primary structure of proteins?

  It is the sequence of amino acids in a polypeptide chain
• What type of bond forms between amino acids in a polypeptide chain?

  A peptide bond
• What process forms a peptide bond?

  A condensation reaction
• What happens during hydrolysis of a peptide bond?

  Water is used to break the bond
• What is the secondary structure of proteins?

  It refers to the folding of the polypeptide chain into alpha-helices and beta-sheets
• What holds the secondary structure of proteins together?

  Hydrogen bonds
• What is the tertiary structure of proteins?

  It is the overall 3D shape of a protein formed by further folding
• What types of bonds are involved in the tertiary structure of proteins?

  Disulfide bonds, ionic bonds, and hydrogen bonds
• What is the quaternary structure of proteins?

  It is the structure formed by the assembly of multiple polypeptide chains
• What is an example of a globular protein?

  Haemoglobin
• What is an example of a fibrous protein?

  Collagen
• What is the Biuret test used for?

  To test for the presence of proteins
• What is the crucial component of the Biuret test?

  Cu²+ from CuSO₄
• What color change indicates a positive result in the Biuret test?

  From blue to purple
• What is the role of enzymes in biological reactions?

  They act as biological catalysts to speed up reactions
• What is activation energy?

  The minimum amount of energy required for a reaction to occur
• How do enzymes lower activation energy?

  By forming an enzyme-substrate complex that distorts the substrate
• What is the induced fit model of enzyme action?

  The active site changes shape to fit the substrate upon binding
• What happens to the enzyme after the reaction is complete?

  The enzyme returns to its original shape
• What is the difference between the lock and key model and the induced fit model?

  The lock and key model is rigid, while the induced fit model is dynamic
• What is an example of a substrate for amylase?

  Carbohydrates
• What is an example of a substrate for protease?

  Proteins
• What is an example of a substrate for lipase?

  Lipids
• How do enzymes exhibit specificity?

  They have a specific active site that fits only certain substrates
• What is the significance of the primary structure of an enzyme?

  It determines the shape and function of the enzyme
• What is the general shape of globular proteins?

  Compact and ball-shaped
• Why do hydrophilic groups face outwards in globular proteins?

  To enable solubility in water
• What is the general shape of fibrous proteins?

  Long and thin, like ropes
• Why do hydrophobic groups face outwards in fibrous proteins?

  To make the protein insoluble
• What are the key differences between fibrous and globular proteins?

  • Fibrous proteins:
  • Long and thin
  • Structural functions
  • Insoluble (e.g., collagen, keratin)

  
  

  • Globular proteins:
  • Compact and ball-shaped
  • Metabolic functions
  • Soluble (e.g., enzymes, hormones)
• What are the steps involved in enzyme action?

  1. Substrate binds to the active site
  2. Enzyme-substrate complex forms
  3. Structural changes occur
  4. Reaction takes place, producing products
  5. Enzyme returns to original shape
• What are the types of bonds involved in protein structures?

  • Primary: Peptide bonds
  • Secondary: Hydrogen bonds
  • Tertiary: Disulfide bonds, ionic bonds, hydrogen bonds
  • Quaternary: Interactions between multiple polypeptide chains
• What are the characteristics of enzymes?

  • Biological catalysts
  • Specific active sites
  • Lower activation energy
  • Reusable after reactions
• What is the significance of the active site in enzymes?

  • Specific shape for substrate binding
  • Determines enzyme specificity
  • Site of catalysis for reactions