water

• water makes up about 80% of a cell's contents
• water helps with temperature control because it has a high latent heat of vaporisation and a high specific heat capacity
• water molecules have a simple structure. one atom of oxygen and two atoms of hydrogen joined by a shared electron
• shared negative hydrogen electrons are pulled towards the positive oxygen atom, making the other side of each hydrogen atom slightly positively charged
• the unshared negative electrons on the oxygen atom give it a slight negative charge
• water is polar molecule - it has a partial negative charge on one side and partial positive charge on the other
• hydrogen bonding is a result of the polarity of water molecules
• hydrolyis reaction requires a molecule of water to break a bond. a condensation reaction releases a molecule of water when a new bond is formed
• amino acids are joined together to make polypeptides (proteins) by condesation reactions
• energy from ATP is released through a hydrolysis reaction