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• Structure: collagen and keratin are the chief constituents of

  skin, bone, hair and nails.
• Catalyst: virtually all reactions in living systems are catalyzed by proteins called enzymes.
• Movement: muscles are made up of proteins called myosin and actin.
• Transport: hemoglobin transports oxygen from the lungs to

  the cells; other proteins transport molecules across cell

  membranes
• Hormones- many hormones are proteins (insulin, oxytocin, human growth hormone.
• Proteins have four levels of structure:
• Functions of Lipids:

  ✓ Precursors of hormone

  ✓ It helps in digestion

  ✓ It provides store of energy

  ✓ It provides metabolic fuel

  ✓ Part of cell membrane