Lipids Flashcards
What elements are present in lipids?
Carbon, Oxygen and Hydrogen. (They have a lower proportion of oxygen than carbohydrates).
Describe the solubility of lipids:
They are insoluble in water (with the exception of glycerol), but are soluble in organic solvents such as ether or benzene.
Compare the densities of lipids with the density of water:
Lipids are less dense (lighter) than water.
Phospholipids, cholesterol and glycolipids are all lipid types that form major components of what cell feature?
The cell membranes.
What is the structure of glycerol?
Three carbon alcohol which contains three hydroxyl (-OH) groups.
Explain how a triglyceride is formed:
A glycerol molecule has three functional (-OH) groups that all react with a fatty acid to form an ester. The single molecule of glycerol and the three fatty acids is called a triglyceride.
What is released in a condensation reaction:
The joining of molecules by the removal of water.
What is a hydrolysis reaction:
Hydrolysis is the splitting of molecules through the addition of water.
What is the functional group of fatty acids?
They have an acidic (-COOH) group.
What is the general formula of a fatty acid?
R - COOH
In a fatty acid, what is the side chain (R)?
Chemically variable group, but it is often hydrogen or an alkyl-group, such as CH3 or C2H5
What is often referred to as the ‘tail’ of the fatty acid, and what properties does it have?
The ‘R’ group is the tail, they are hydrophobic.
Which is the enzyme that catalyses the digestion of triglycerides?
Lipase enzymes (breaks down fat)
Where does the synthesis of triglycerides take place?
In fat storage deposits.
Compare the energy content of triglycerides in comparison to the content of carbs and proteins.
Triglycerides contains much more energy than both carbs and proteins per gram.
Suggest why desert animals such as camels would store triglycerides:
When triglycerides are oxidised, they yield water which is useful for the lack of available water in the desert.
Suggest why fat is a thermal insulator for the body:
Triglycerides are poor heat conductors so fat layers maintain the heat inside the body as it is harder to pass through the skin.
Suggest why an aquatic animal such as a whale would store huge masses of “blubber” (fat):
Fat is a very good thermal insulator which stops the cold temperatures of the oceans from affecting them. It also acts as relative buoyancy as it is less dense than water.
Suggest a reason for the thick layer of fat that surrounds the mammalian kidney:
It provides cushioning from shocks and hits to the kidneys to prevent damage.
What forms an ester bond?
A condensation reaction between an alcohol group and an acid group.
What is the general formula of a saturated fatty acid?
Cn H2n 02
What is the difference between a saturated and unsaturated fatty acid?
A saturated molecule has no C=C double bonds, where as an unsaturated molecule does.
Suggest why a fatty acid would be unsaturated:
The acid does not contain all of the hydrogen atoms required to fill the bonds, therefore C=C double bonds must be created.
If a fatty acid has no C=C double bonds, it is said to be what type of molecule?
Saturated
If a fatty acid has one or more C=C double bonds, it is said to be what type of molecule?
Unsaturated
What is formed when unsaturated fatty acids are combined with glycerol?
oils (which are liquid at normal atmospheric pressure.)
What is formed when saturated fatty acids are combined with glycerol?
saturated fats (which are solid at normal atmospheric pressure.)
Sardines, tuna and eels are referred to as “oily fish”, suggest what type of lipid they contain and why:
High amounts of unsaturated fat as this combines with glycerol to form oils.
Suggest the product that occurs when Oleic oil is combined with glycerol:
Olive Oil
Suggest the product that occurs when Linolenic and linoleic oils are combined with glycerol:
Linseed oil.
