Lipids Flashcards
What is a lipid?
A mix of hydrophobic compounds
What elements are lipids composed of?
CHO
Carbon
Hydrogen
Oxygen
What difference in elements is there between lipids and carbohydrates?
More hydrogen and less oxygen in lipids
Describe the solubility of lipids
- Insoluble in water
- Soluble in organic solvent (e.g. alcohol)
What are the most well known lipids?
Fats and oils
What other element can be found in lipids (smaller proportion)
Phosphorus
What are two ways to categories lipids?
- Simple
- Complex
What is included as a simple lipid?
Steroids and terpenes
What is included as a complex lipid?
Trigylcerides Phospholipids and waxes
Why are lipids not soluble in water?
They are non-polar molecules, therefore aren’t attracted to the polarity of water molecules
What is a triglyceride composed of?
One glycerol molecule
Threee fatty acids
What bonds are between the glycerol molecule and the fatty acids?
Ester bonds
How does a triglyceride form?
Process of esterification:
- Condensation reaction removing 3 water molecules, and leaving a triglyceride
How do you break down a triglyceride?
Hydrolysis reaction - water is added to break the ester bonds
What group does glycerol belong to?
Alcohols
What group does fatty acids belong to?
Carbonyx group (contains -COOH) with a hydrocarbon chain attached
What makes a fatty acid chain saturated?
No more hydrogen atoms can be added to the carbon atoms.
There are only single bonds (no double bonds present).
Why is a saturated fatty acid usually a solid?
As there are no unsaturated carbon atoms, there are no bends, meaning it can pack closely together.
What makes a fatty acid chain unsaturated?
Double bonds are present, meaning it could take more hydrogen atoms
Why are unsaturated fatty acids usually liquid?
As a result of the double bonds, the fatty acid bends, which prevents it from packing closely together.
Explain SSS and DUL
SSS - single (bonds) saturated (lipids) soilid (room temp.)
DUL - double (bonds) unsaturated (lipids) liquid (room temp.)
What is a phospholipid?
A modified triglyceride that contains phosphorous.
- this phosphate group replaces one of the fatty acids
What difference in properties is there between phospholipids and triglycerides?
Due to phospholipids containing phosphate ions, it is polar, meaning it is soluble in water.
Describe the polarity within a phospholipid
Phospholipid has a hydrophilic head (charged) and a hydrophobic tail (non-polar)
What is the function of triglycerides?
- Plants contain unsaturated triglycerides (usually oils)
- Human diet - unsaturated fats
What can phospholipids form due to their polarity?
Phospholipid bilayer
What is the function of phospholipid?
Separate aqueous environment from cytosol within cells
Where does the body manufacture cholesterol?
Liver and intestines
What is the role of cholesterol?
- Regulate fluidity and add stability through the membrane
- Important role in the formation of cell membranes
Describe cholesterol’s solubility
Not soluble
