Lipids Flashcards
What are lipids? How are they good stores of energy and what are they used for?
Lipids are fats, oils and waxes that produce twice as much energy as carbohydrates .They are osmotically inactive in water and are used for energy & insulation to make cell membranes and to spare the use of protein for energy. Contain C, H and O2.
What are triglycerides?
A type of lipid formed by 3 fatty acids and 1 glycerol molecule in a condensation reaction, which forms 3 ester bonds.
What is an ester bond?
A carbon joined to 3 other atoms: a single bond to a carbon, a double bond to an oxygen, and a single bond to an oxygen.
What is the difference between unsaturated and saturated fat?
Saturated fats contain no double bonds between carbon atoms, and have all hydrogen present. Found in meat such as beef and chicken. Unsaturated fats have 1 or more double bonds and don’t have all hydrogen present. Found in fish, nuts, olives and seeds, usually called oils.
What is the general formula of fats?
R-COOH. The R represents a long hydrocarbon chain and the COOH is the carboxylic group. They end in COOH.
What are phospholipids?
Lipids containing a phosphate group, which replaces a fatty acid so that the fat is now made up of 2 fatty acid, 1 glycerol and a phosphate group. They are joined in a condensation reaction.
How are phospholipid layers formed and why are they good for their role?
A layer is formed from 1 thin layer being in contact with water. The hydrophilic heads are attracted to the water unlike the hydrophobic tails, which project outwards to repel. In the cell membrane, a bilayer of phospholipids prevents water entering the cell and thus keeps it rigid and strong as the tails are attracted to one another and away from the water.
How can lipids be hydrolysed?
Lipids can be hydrolysed by heating with an acid or alkali or by using the enzyme lipase at opt. temp. and pH
What is the emulsion test for lipids?
Add a small amount of sample into a tube with 2cm3 of ethanol
Shake mixture so fat dissolves
Add this to water in another test tube and mix contents
A white/ cloudy emulsion of fat droplets indicates present lipid.
