Biological molecules

• Membrane


  Role of each component
• Biological molecule (biomolecule) is a chemical compound that naturally occurs in living organisms
• Types of biological molecules

  • Inorganic molecules (such as water)
  • Organic molecules (such as carbohydrates)
• Carbon is an element present in all organic biological molecules
• Carbon atoms


  Can join to form chains or ring structures
• Biological molecules


  Can form very large macromolecules often by polymerization
• Monomers


  Sub-units from which larger molecules are constructed
• Other elements such as oxygen and hydrogen are always present whereas nitrogen is only sometimes present in biological molecules
• Biological molecule (biomolecule)


  A chemical compound that naturally occurs in living organisms
• Types of biological molecules

  • Inorganic molecules (such as water)
  • Organic molecules (such as carbohydrates)
• Carbon is an element present in all organic biological molecules
• Carbon atoms


  Can join to form chains or ring structures
• Macromolecules


  Biological molecules that are very large, often formed by polymerization of monomers
• Monomers


  Sub-units that macromolecules are constructed from
• Polymers


  Macromolecules made of long chains of monomers held together by chemical bonds
• Examples of polymers


  • Carbohydrates
  • Proteins
  • Nucleic acids
• Lipids


  Important biomolecules that are not polymers
• Cells need chemical substances to make new cytoplasm and to produce energy
• Cells have specialized functions and differing needs
• Components of all cells

  • Water
  • Carbohydrates
  • Lipids
  • Proteins including enzymes
  • Nucleic acids
• Water


  A good solvent, the medium for enzymatic and chemical reactions in living cells
• Without water, life would not exist on this planet
• Water content in cells

  Typically forms between 70% and 95% of cells, about 60% in humans
• If water content falls, cells will die
• Water


  Provides an environment for aquatic organisms
• Water


  • Has unusual properties
• Water molecule


  Made up of two 'H' atoms bonded to an 'O' atom, with a slight positive charge on 'H' and slight negative charge on 'O'
• Polarity


  Water molecules have two poles, a positive hydrogen pole and a negative oxygen pole
• Hydrogen bond


  A bond formed in the liquid state of water, provides useful properties
• Water


  • Has a high specific heat capacity, allowing large bodies of water to absorb a lot of heat and resist temperature changes
  • Has a high latent heat of vaporization, requiring a relatively great amount of heat to evaporate
• Hydrogen bonds


  Bonds formed between molecules
• Water molecule


  • Partial positive charge on hydrogen
• Figure 2.1 Structure of a water molecule, its polarity and formation of hydrogen bonds between water molecules
• Specific heat capacity


  The amount of heat that must be absorbed in order for 1 g of a substance to change its temperature 1°C
• Water has a high specific heat capacity
• Large bodies of water, like oceans, absorb a lot of heat


  They resist changes in temperature
• Oceans moderate the climate of coastal areas


  Resulting in relatively little temperature change
• Latent heat of vaporization


  The relatively great amount of heat needed to evaporate water
• Evaporation of sweat


  Significantly cools the body surface
• Water as a universal solvent

  Water dissolves all polar and ionic substances