Lipids Flashcards
What are lipids?
Organic molecules found in every type of cell. They are insoluble in water but soluble in organisms solvents. Most of the lipids we eat are triglycerides which are used as energy stores.
What are triglycerides made up of?
Three fatty acids and one glycerol molecule linked by condensation reactions
What is the bond that forms between each fatty acid and the glycerol known as?
An ester bond. Three ester bonds are formed in a triglyceride. Each is formed in a condensation reaction with the release of a water molecule.
Draw the structure of a triglyceride formation
What is a saturated fat?
If the fatty acid chains in a lipid contain the maximum number of hydrogen atoms they are said to be saturated. In a saturated fatty acid the hydrocarbon chain is long and straight.
What properties do saturated fats have?
Straight, saturated hydrocarbon chains can pack together closely. The strong intermolecular bonds between triglycerides made up of saturated fatty acids result in fats that are solid at room temp.
Draw a saturated hydrocarbon chain
What are monounsaturated fats?
They have one double bond between two of the carbon atoms in each fatty acid chain
What are polyunsaturated fats?
They have a larger number of double bonds
What does a double bond cause?
A kink in the hydrocarbon chain, these kinks prevent the unsaturated hydrocarbon chains packing closely together
What properties do unsaturated fats have?
Increasing the distance between the molecules weakens the intermolecular forces between the unsaturated triglycerides resulting in oils that are liquid at room temp
How do you make unsaturated fats saturated?
Unsaturated fats can be made more solid at room temp by adding hydrogen to the double bond making them saturated
Draw an unsaturated hydrocarbon chain
What is cholesterol?
Cholesterol is a short lipid molecule which is essential for good health
What functions does cholesterol have?
• It is a vital component of cell membranes with roles in their organisation and functioning
• Steroid sex hormones and growth hormones are made from it
• Bile salts, involved in lipid digestion, are also formed from it
Where is cholesterol made?
Is it made in the liver from saturated fats and also obtained in our diet. It is found associated with saturated fats in foods such as eggs, meat and dairy.
Other than supplying energy, what else do fats provide?
As well as supplying energy in the diet, fats provide a source of essential fatty acids that the body needs but cannot synthesise
Why must fats be present in a balanced diet?
To avoid deficiency symptoms and to absorb fat-soluble vitamins (A, D, E and K)
