Biological molecules: lipids Flashcards
describe the structure of a triglyceride molecule
a molecule of glycerol bonded to three fatty acid molecules
how does a fatty acid molecule join to a glycerol molecule?
a fatty acid molecule joins a glycerol molecule through the process, esterification where an ester bond is formed and a water molecule. It is also considered a condensation reaction. 3 water molecules are produced when three fatty acid molecules bind to a glycerol molecule.
how does the triglyceride molecule breakdown?
3 water molecules are needed which is an example of a hydrolysis reaction.
what are the two properties of triglycerides?
-they are non-polar molecules and hydrophobic. Triglycerides are used for water-proofing in aquatic birds
-a great deal of energy is released from triglycerides due to the large number of carbon and hydrogen atoms
Describe the structure of a phospholipid
two fatty acid molecules are attached to a glycerol molecule. The glycerol molecule is also bonded to phosphate. The phosphate group is hydrophilic and polar.
Describe the structure of a fatty acid
a chain of carbon atoms bonded to hydrogen atoms which is bonded to a carboxylic group at the end.
what are saturated and unsaturated fatty acids?
saturated fatty acids have no carbon double bonds, unsaturated fatty acids have carbon double bonds. A fatty acid with one carbon double bond is called monounsaturated. Two or more carbon double bonds is called polyunsaturated.
why are some fats liquid?
The presence of carbon double bonds causes the molecule to kink/bend therefore they can’t pack close together, making them liquid at room temp. Unsaturated triglycerides tend to be more healthy.
Describe the structure of cholesterol and what family of lipids is it in?
It is apart of a family of lipids called sterols. The hydroxyl group is hydrophilic and the rest of the molecule is hydrophobic.
how can cholesterol insert into cell membranes?
the hydrophilic hydroxyl group interact with the phosphate head and the rest of the cholesterol molecule interacts with the hydrophobic fatty acid tails. Cholesterol maintains the fluidity of the membrane.
why is cholesterol used as a starting point for a range of hormones e.g oestrogen and testosterone?
so the hormones can pass through membranes
cholesterol is used to make vitamin D, what is vitamin D used for?
for the proper development of bones
cholesterol is used in the liver to produce bile. What is the function of bile?
bile increases the rate of digestion of lipids
are lipids soluble?
no
what is the role of a lipid?
role in protection, insulation and storage
