3.5 Lipids Flashcards
What elements do lipids contain?
Carbon, hydrogen, oxygen
Are lipids considered as polymers?
No, not made up of long chains of monomers
What is the role of lipids?
-Energy supply - can be oxidised to provide energy to cells
-Structural components - phospholipids are used in cell membranes
-Waterproofing - insoluble lipoids are used to form water-resistant barriers
-Insulation - help retain heat or act as electrical insulators
-Protection - delicate organs surrounded by a layer of fat
What are lipids?
Macromolecules
What are macromolecules?
Large complex molecules with as large weight
Are lipids soluble in water?
No, as they are non-polar, electrons distributed evenly, no positive or negative areas within the molecule
What is the structure of a triglyceride?
-One glycerol molecule with three fatty acid tails
-Each fatty acid tail contains a hydrocarbon chain (R) which can vary in length
-Both glycerol and fatty acid groups contain OH groups which interact
What is the name of the bond in lipids?
Ester bond
What is esterification another example of?
A condensation reaction
What are the properties and function of triglycerides?
-Fatty acid chains are hydrophobic which makes them insoluble
-Long hydrocarbon tails = many carbon-hydorgen bonds can be broken to release energy
-Low mass to energy ration = lots of energy can be stored in a small volume
-Insoluble = do not affect water potential as they are large and non-polar
-High ration of hydrogen to oxygen atoms = release water when oxidised
What is meant by hydrophilic?
Section of a molecule which is attracted to water
What is meant by hydrophobic?
Section of a molecule which is repulsed to water
What happens when a triglyceride undergoes a condensation reaction?
-The hydroxyl groups on the glycerol and on the 3 fatty acids react together to release 3 water molecules
-Results in three ester bonds between the glycerol and the fatty acids
What happens when a triglyceride undergoes a hydrolysis reaction?
-The addition of three water molecules breaks the ester bonds
-This separates the glycerol and the fatty acids
What is the structure of a phospholipid?
-Hydrophilic head, containing glycerol molecule and a phosphate group
-Hydrophobic tail - containing 2 fatty acids tails
What is the function of triglycerides?
Energy store
What elements do phospholipids contain?
Phosphorous, carbon, hydrogen, oxygen
What bonds are in phospholipids?
Ester
How phospholipids react with water?
-Non-polar fatty acid tail which is hydrophobic
-Charged heads are polar and are attracted to water, are hydrophilic
-When placed in water, arrange themselves in a bilayer, hydrophilic heads facing out towards water, and hydrophobic tails facing in away from water
What is the uses of phospholipids?
Membranes, hormones (eg. testosterone)
What are the two types of fatty acids?
Saturated and unsaturated
What are saturated fatty acids?
-Fully saturated with hydrogen, all carbon atoms are bonded to the maximum number of hydrogen atoms
-No carbon-carbon double bonds
-Have higher melting points, usually solid at room temperature
What is it called is there is one double bond in a hydrocarbon chain?
Monounsaturated
What is it called is there is two or more double bonds in a hydrocarbon chain?
Polyunsaturated
