Biomolecules- Lipids Flashcards
What elements are found in lipids?
Carbon, hydrogen, oxygen (in proportion there is less oxygen)
What type of compound are they?
They are non polar compounds so insoluble in water that can dissolve in other non-polar substances and organic solvents.
How are triglycerides formed?
They are formed by the combination of one glycerol molecule and three fatty acid chains these are joined by a condensation reaction where three molecules of water are removed and three ester bonds are formed between the glycerol and fatty acids.
How are phospholipids formed?
These have two fatty acid attach to the glycerol and one phosphate group.
In terms of solubility what is the difference between a triglyceride and a phospholipid?
In the phospholipid each molecule has one end that is soluble in water. It contains a polar head which is hydrophilic as it contains a phosphate group which has a lot more oxygens attached to the glycerol. At the other end is the non polar tail which is hydrophobic as the fatty acid tails don’t contain any oxygen atoms. However a triglycerides is not soluble in water and is entirely hydrophobic.
What role does waxes have?
They melt above 45° and have a waterproofing role in both animals and in plants. This reduces water loss in insects exoskeleton and in the cuticle of plants.
What is the role of phospholipids?
In biological membranes
Electrical insulation - the myelin sheath surrounds the axons of the nerve cells.
What is the role of triglycerides?
Energy source and storage: energy is reserved in animals and plants as lipids and they contain more hydrogen and carbon bonds than carbohydrates. 1 g of fat provides twice as much energy as the same mass of carbohydrates.
Thermal insulation: when stored under the skin lipids insulate against heat loss in the cold and heat gain when it is very hot.
Protection: fat is stored around delicate organs such as kidneys protecting against any physical damage.
Metabolic water: this is water released during chemical reactions in the body triglycerides produce a lot of metabolic water when oxidised.
What is the role of waxes?
Waterproofing: in terrestrial organisms waxes reduce water loss such as in insects exoskeleton and in the cuticle of plants.
What is a saturated fat?
This is when the hydrocarbon chain has single carbon to carbon bonds it is saturated as all carbon atoms are linked to the maximum possible number of hydrogen atoms.
What state is saturated fats at room temperature?
It is a straight zigzag which means that the molecules can align readily so fats are solid. They remain semi-solid at body temperature so are useful in storage for animals with animal lipids often containing saturated fatty acids.
What is an unsaturated fat?
It is when the hydrocarbon chain has at least one carbon to carbon double bond which means that the maximum possible number of hydrogens attached has not been reached.
What state is unsaturated fats at room temperature?
As the chain is unsaturated the chain gets a kink which means that the molecules cannot align uniformly and the lipid does not solidify readily unsaturated fats are oils which remain liquid at room temperature plant lipids are often unsaturated and occur as a oils e.g. sunflower and olive oil.
What does it mean by the term mono-saturated?
It is when there is one double bond between the carbons in the hydrocarbon chain.
What does it mean by the term poly-saturated?
It is when there are many double carbon bonds in the hydrocarbon chain.
