lipids

• lipids are only soluble in organic solvents like alcohol and ether
• there are 2 types of lipids: saturated and unsaturated
• saturated lipids don't contain any carbon-carbon double bonds (found in animal fats)
• unsaturated lipids do have carbon-carbon double bonds and melt at a lower temperature than saturated lipids (found in plants)
• the greater the number of unsaturated bonds the weaker the intermolecular bonding which gives it a low melting point (this is because they don't need a lot of energy to break the bonds)
• saturated fats are solid at liquid temperature while unsaturated fats are liquid at room temperature
• what is found in a triglyceride?

  • glycerol and fatty acids
• how many fatty acids are found in triglycerides?

  3
• what is found in a phospholipid?

  glycerol, 2 fatty acids and phosphate
• triglycerides are a good use of energy and phospholipids have a structural role in the membrane
• lipids aren't polymers as the chain isn't consisted of polymers. instead they are non-polar molecules that don't dissolve in the water
• for the structure of triglycerides: the glycerol is an organic alcohol that has 3 hydroxyl groups while the fatty acids are organic acids that have a carboxyl group. the glycerol and the fatty acids are connected together by a hydrocarbon trail
• triglyceride molecule is formed by a condensation reaction
• when triglycerides are formed from condensation reactions, they form water as 1 oxygen and 2 hydrogen atoms are removed in the reaction.
• an ester bond is a covalent bond between a carboxyl group and an alcohol and is formed in triglycerides
• to make a triglyceride - you need 3 condensation reactions and form 3 water molecules. To breakdown triglycerides, you need to use 3 hydrolysis reactions
• there are 2 types of triglycerides = fats and oils
• fatty acids with hydrocarbon chains that don't contain a double bond are saturated while fatty acids that have double bonds are monounsaturated. fatty acids that have multiple double bonds are polyunsaturated.
• when a fatty acid has unsaturated hydrocarbon chains their tails slightly bend
• are unsaturated lipids compactable?

  no
• saturated lipids are fats as they are solid at room temperature. unsaturated lipids are oils as they are liquid at room temperature
• triglycerides can be broken down into glycerol and fatty acids which is good as they release a lot of energy due to the amount of carbon hydrogen bonds that's been broken down
• what's the equation for metabolic reactions?

  triglyceride + oxygen ----- carbon dioxide + water + energy
• triglycerides have good energy stores as they provide more energy per unit of mass
• triglycerides are large and non - polar and insoluble in water which means they don't easily effect the osmosis balance.
• fats are used as a thermal insulator to protect internal organs
• fats are less dense than water so they aid in buoyancy
• in phospholipids one of the fatty acids has been replaced by phosphate which is attached to the glycerol but on the opposite side to the other fatty acids
• phospholipids also have a condensation reaction but with phosphoric groups and hydroxyl groups with the glycerol.
• A phosphate ester bond is formed from the condensation reaction of a phosphate group and an alcohol and forms a molecule of water
• when surrounded by water, the phospholipids dissociate hydrogen from the phosphate group which gives them a negative charge
• because of its negative charge, the phospholipid head is hydrophilic and the tails are hydrophobic
• Hydrophobic is a molecule that does not readily dissolve in water and tries to avoid water
• Hydrophilic is a molecule that is attracted to water.
• phospholipids might form a layer on the surface of the water and may form a monolayer of phospholipids called micelles
• phospholipids might form a bilayer (which is 2 layers of phospholipids)
• in the phospholipid bilayer, the hydrophilic heads form 2 rows on the outside facing forward while the hydrophobic tails are sheltered in the middle away from the water which makes the charge of the phospholipid bilayer more stable
• the phospholipid bilayer is good as it can make the cell membrane change shape due to the fluidity
• what are the roles of phospholipid bilayer?

  Cell membrane structure and is an electrical insulator
• why are phospholipid bilayers good electrical insulators?

  because the middle doesn't allow water inside, molecules that dissolve in water cant come through so easily. only small, non-polar molecules can pass through which makes the membrane permeable