Unit 2 - Module 1 - Lipids Flashcards
(21 cards)
What are the functions of lipids?
Energy source Energy storage Biological membranes Insulation Protection Some hormones
What percentage of organic matter do lipids make up?
5%
What forms lipids?
Glycerol and fatty acids.
What is the structure of glycerol?
3-carbon chain with 3 OH groups.
Propan-1,2,3-triol.
What is the structure of the fatty acid?
Differ, there are essential fatty acids.
All fatty acids have a carboxyl group -COOH, with a hydrocarbon chain.
What effect do C=C bonds have in hydrocarbon chains?
They change the shape pushing molecules in lipid apart.
This makes them more fluid.
What are fats?
Lipids that at room temperature are solid. Often mainly saturated fatty acids.
Often animal lipids.
What are oils?
Lipids that at room temperature are liquid.
Often contain many unsaturated fatty acids.
Often plant lipids.
What is the structure of triglycerides?
One glycerol molecule bonded to three fatty acid molecules.
What is the name of the bond that forms between a glycerol molecule and fatty acids?
An ester bond
-O-
Why are triglycerides insoluble in water?
The charges in the molecule are distributed evenly around the molecule. Therefore hydrogen bonds cannot form between molecule and water, and so don’t mix.
What is the main role of triglycerides?
A compact energy store.
What is the structure of a phospholipid?
A glycerol molecule bonded to two fatty acids and a phosphate group.
How do organisms control fluidity of membranes?
How saturated or unsaturated phospholipids are.
What is an example of controlling fluidity of a membrane!
In colder climates organisms have an increased number of unsaturated fatty acids. This ensures membranes remain fluid despite low temperatures.
How are lipids used in respiration?
Hydrolysis of the ester bonds.
Glycerol and fatty acids can both be broken down completely to carbon dioxide and water. This releases energy used to make ATP.
How much energy does respiration of one gram of lipid give?
Twice as much energy we the respiration of one gram of carbohydrate.
What is the structure of cholesterol?
Four carbon-based ring structures joined together.
What is the main role of cholesterol?
Forms a small, thin molecule that fits into lipid bilayer giving strength and stability.
What other roles does cholesterol have?
It is used to form steroid hormones, such as testosterone, oestrogen and vitamin D.
Why does excess cholesterol cause problems in humans?
In bile cholesterol can stick together to form lumps called gallstones.
In blood can be deposited in the inner linings of blood vessels, causing atherosclerosis, which can result in circulatory problems.
