haemoglobin and collagen

• What is haemoglobin, and where is it found?

  • Haemoglobin is a globular protein found in red blood cells, carrying oxygen
• Describe the quaternary structure of haemoglobin?

  • 4 polypeptide chains: two α–globins and two β–globins, each with a haem group.
• How are the globin subunits arranged in haemoglobin?

  • The globin subunits are held together by disulphide bonds
  • inward-facing hydrophobic R groups
  • outward-facing hydrophilic R groups
• Why are the arrangements of R groups important for haemoglobin's function?

  • Proper R group arrangements are crucial for haemoglobin's function; changes can lead to conditions like sickle cell anaemia
  • In sickle cell anaemia, a base substitution results in valine replacing glutamic acid, making haemoglobin less soluble.
• what is the haem group?

  • The prosthetic haem group contains iron II ions,
  • allowing reversible oxygen binding to form oxyhaemoglobin,
  • giving haemoglobin a bright red colour
  • Each haemoglobin molecule can carry four oxygen molecules due to its four haem groups
• What is the role of haemoglobin in the body?

  • Haemoglobin binds oxygen in the lungs and transports it to tissues for aerobic metabolic pathways.
• How does haemoglobin enhance the transport of oxygen?

  • Haemoglobin's solubility allows efficient oxygen transport in the bloodstream
• why is the haem group significant?

  • The haem group in haemoglobin enhances oxygen binding by altering the protein's structure,
  • which increases affinity for subsequent oxygen molecules
• how does iron II facilitate oxygen binding?

  • The iron II ion in the haem group enables reversible oxygen binding
  • amino acids in haemoglobin aren't well-suited for oxygen binding
• Why is oxygen binding more efficient when bound to haemoglobin?

  • due to its alteration of quaternary structure when oxygen binding
  • which increases its affinity for subsequent oxygen molecules
• the structure of collagen

  • the most common structural protein found in vertebrates
  • formed from three polypeptide chains closely held together by hydrogen bonds
  • form a triple helix, known as tropocollagen
  • its an insoluble fibrous protein
• How many polypeptide chains form a collagen molecule?

  • Each polypeptide chain in collagen is helical in shape
  • glycine, proline, and hydroxyproline are most common.
• How are collagen molecules held together to form fibrils?

  • Covalent bonds form cross-links between R groups of amino acids in interacting triple helices when they are arranged parallel to each other
  • which hold collagen molecules together to form fibrils
• how are collagen fibers positioned to withstand forces?

  • Collagen fibers are positioned in alignment with the forces they withstand for optimal strength and support
• What structural role does collagen play in connective tissues?

  • Collagen serves as a flexible structural protein in connective tissues
• what is tensile strength?

  • The numerous hydrogen bonds within its triple helix structure provide collagen with great tensile strength,
  • which enable it to withstand large pulling forces without stretching or breaking
  • staggered ends of collagen contribute to strength
• Why is collagen insoluble in water?

  • The length of collagen molecules makes them insoluble in water, as they take too long to dissolve
• why is collagen a stable protein?


  its enhanced by the high proportion of proline and hydroxyproline amino acids, which repel each other and prevent unfolding