Unit 1: Lipids Flashcards
why are lipids important?
provide long term source of energy function as hormones structural component of plasma membrane provide insulation for animals buoyancy for aquatic animals
what is the solubility of lipids?
insoluble in water, soluble in organic solvents
what are the three main groups of lipids?
triglycerides, phospholipids and steroids
what are triglycerides composed of?
three fatty acids and a glycerol molecules by esterification
what is glycerol composed of?
3 carbons and 3 OH groups
what are fatty acids composed of?
a carboxylic group group at one end and a hydrocarbon tail at other
what is the main function of a triglyceride?
an energy store
what do plants and animals store energy as?
triglycerides as oil - plants
triglycerides as fats - animals
what happens to triglycerides during aerobic respiration?
triglycerides break down to form a 2c carbon compound that is fed into the citric acid cycle as acetyl coenzyme A
what is a saturated fatty acid?
has no C-C double bond, and have a very straight structure, packed closely
what is a unsaturated fatty acid?
have one or more C-C double bond, kinked in structure and cannot pack closely
what is released in the breakdown of triglycerides?
water
what is a phospholipid made up of?
two fatty acids, phosphate group and glycerol
what bonds joins the phosphate and the fatty acids to the glycerol?
an ester bond
explain what the head and tail of the phospholipid are?
the head is a phosphate group - polar - hydrophilic, the tail is a long hydrocarbon group - non polar - hydrophobic
what does cholesterol do to the membrane?
stiffen it
why are unsaturated fatty acids present for membranes?
they add fluidity since the kinks don’t allow them to be tightly packed
allows transport of substances across the bilayer
explain the connection between temperature and unsaturated and saturated fatty acids.
The colder the temperature the membrane is exposed to the more unsaturated fatty acids are present.
The warmer the temperature the more saturated fatty acids there are
what structure do steroids have in common?
a 4 ring structure of 17 carbons
why are steroids classed as lipids?
they are soluble in organic compounds but not water
what makes a steroid different from another?
side chain
what is the role of steroids?
as they can pass through the membrane, the play a part in cell signalling and hormonal function
what additional components does cholesterol have?
an OH at the bottom left and an C8H17 on the top right
what are the roles of cholesterol?
fit into the hydrophobic part of the phospholipid and reduces movement in the membrane
prevent solidification of the membrane at low temp
