Water & Proteins

• Carbohydrates are used to store and supply energy and can be structural
• proteins are used for transport and structure, also the basic components of all enzymes, hormones, antibodies, haemoglobin and many more materials
• Lipids are part of cell membranes, insulators and protection and also a minor energy supply
• Nucleic acids are made of nucleotides. These form DNA and RNA
• Enzymes are made of proteins. They are biological catalysts.
• Water is a polar molecules which is where it has one area of positive charge and one area of negative charge. The slight negative charge on the oxygen atom makes it attract the slightly positive hydrogen.
• features of water:

  • good solvent
  • high specific heat capacity
  • high latent heat of vaporisation
  • high cohesion
• As water is a polar molecule water is attracted to any other substance that is also polar
• Substances that can dissolve in water are hydrophylic.
• Substances that can't dissolve in water are hydrophobic
• Triglycerides (fats & lipids) and large polymers do not dissolve in water
• Anything polar cannot go through a membrane
• Specific heat capacity is the amount of heat required to raise the temperate by 1 degree.
• Water has a high specific heat capacity due to many of the hydrogen bonds present in water. It takes a lot of thermal energy to break these bonds, this means the temperature of water does not fluctuate greatly.
• Why is high specific heat capacity good for water?

  Vital in maintaining temperatures that are optimal for enzymes so they don't denature.
• What is latent heat of vaporisation?

  To change state from a liquid to gas
• Water has a high latent heat of vaporisation as a great amount of thermal energy must be absorbed by water to break the hydrogen bonds and evaporate.
• Why is high latent heat of vaporisation good for water in humans?

  sweating is used as a cooling mechanism so that sweat can evaporate resulting in your body cooling. This is due to the molecules with the highest kinetic energy being lost to evaporation.
• water has cohesion to be able to be transported around the body, molecules will stick together via an intermolecular force. Hydrogen bonds between water molecules allow for strong cohesion between water molecules
• When is cohesion in water used?

  • Allows water to create capillary action which is the process by which water can rise up the xylem of the plant against the force of gravity due to the process of transpiration.
  • When it is raining
• Metabolism is the sum total of all biochemical reactions in the body
• polymers are macromolecules that are made up of repeating subunits that are joined end to end, they are easy to make as it is the same reaction repeated many times.
• Polymerisation is the making of polymers
• A macromolecule is a polysaccharide, make proteins and nucleic acids
• A monomer (subunit) is a monosaccharide, make amino acids and nucleotide
• There are two types of metabolism: anabolism and catabolism
• Anabolism is the build up of larger, more complex molecules from smaller simpler ones. this process requires energy
• Catabolism is the breakdown of complex molecules into simpler ones. This process releases energy.
• what are the functions of proteins?

  Cell membranes

  Haemoglobin

  Antibodies

  Enzymes

  Keratin (hair and skin)

  Collagen
• what is the amino acid structure?

  HHN (amine group) - HCR (R group) - COOOH (Carboxyl group)
• This is an amino acid structure

  
• A primary structure is made up of only peptide bonds and is chain like
• A secondary structure is made up of only hydrogen bonds. There are two main structures called alpha helix and beta pleated sheets
• Secondary structures form as a result of hydrogen bonding between different amino acids in chain
• A tertiary structure is the overall 3D shape of a protein. Help together by disulphide bonds, hydrogen bonds, ionic bonds and van der waal forces.
• Hydrogen bonds are between polar groups. share electrons and spend longer at these atoms, forming a slight negative charge. High temperatures and altered pH can split these bonds.
• Ionic bonds are between R groups, which ionise to form positively and negatively charged groups that attract each other. Can be split by changing the pH.
• Disulphide bonds are between sulphar containing R groups of the amino acid cysteine. Made of covalent bonds. Form strong links making it very stable. Bond is broken by reducing agents
• Hydrophobic interaction are between the non-polar side chains of a protein molecule. Once the 2 hydrophobic molecules are close together the interaction is reinforced by van der waal attractions.
• Globular proteins form a spherical mass with a specific 3D shape. They fold up so hydrophilic groups are on the outside and hydrophobic groups are inside the molecule. Molecules which have a chemical function in living organisms like metabolism. They are soluble.