2.2- Lipids 1: Triglycerides Flashcards
What does lipids mean?
A group of substances that are soluble in alcohol rather than water. They include triglycerides, phospholipids, glycolipids and cholesterol
What deos macromolecule mean?
A very large organic molecule.
What does phospholipid mean?
Molecule consisting of glycerol, two fatty acids and one phosphate group.
What are lipids?
Lipids contain large amounts of carbon and hydrogen and smaller amounts of oxygen. They are insoluble in water because they are not polar, and so do nit attract water molecules, but do dissolve in alcohol. The three most important lipids in living things are triglycerides, phospholipids and steroids. These are not polymers but they do have different components bonded together, They are examples of macromolecules.
What is the structure of triglyceride?
Triglycerides are made up of glycerol and fatty acids. There are many different types of fatty acid. We can make many of them in our bodies but some must be ingested’ complete’. These are called essential fatty acids.
What is the structure of glycerol?
Glycerol has three carbon atoms. It is an alcohol, which means it has free -OH groups. There are three-OH groups, which are important to the structure of triglycerides
What is the structure of fatty acids?
Fatty acids have a carboxyl group (-COOH) on one end, attached to a hydrocarbon tail, made only of hydrogen and carbon atoms. This may be from 2 to20 carbons long. The carboxyl group ionises into H+ and a -COO- group. This structure is therefore acidic because it can produce free H+ IONS.
- If a fatty acid is saturated this means that there are no C=C bonds in the molecule.
- If a fatty acid is unsaturated there is a double bond between two of the carbon atoms instead, which means fewer hydrogen atoms can be bonded to the molecules.
- Monounsaturated- a SINGLE C=C bond
- Polyunsaturated- More than one C=C bond
- Having one or more C=C bonds changes the shape of the hydrocarbon chain, giving it a kink where the double bond is. Because theses kinks push the molecules apart slightly, it makes them more fluid. Animal lipids contain lots of saturated fatty acids, which are often solid at 20 degrees. If there are more unsaturated fatty acids, the melting point is lower.
What is the structure of ester bonds?
A triglyceride consists of one glycerol molecule bonded to three fatty acids. A condensation reaction happens between the -COOH group of the fatty acid and the -OH group of the glycerol. Because there are three -OH groups three fatty acid swill bond, hence the name triglyceride. Because it is a condensation reaction, a water molecule is produced and the covalent bond formed is known as an ester bond. In some cases the same type of fatty acids may bond to each -OH group or the fatty acids may be different.
What are he function of triglycerides?
- Energy source
- Energy store
- Insulation
- Buoyancy
- Protection
What is energy source?
Triglcyerides can be broken down in respiration to releases energy and generate ATP. The first step is to hydrolyse the ester bonds, and then both glycerol and the fatty acid can be broken down completely to carbon dioxide and water. Respiration of a lipid produces more water than respiration of a sugar.
What is energy store?
Because triglycerides are insoluble in water, they can be stored without affecting the water potential of the cell. Mammals store fat in adipose cells under the skin. One gram of fat releases twice as much energy as 1g of glucose. This is because lipids have a higher proportion of hydrogen atoms than carbohydrates and almost no oxygen atoms.
What is insulation?
Adipose tissue is a storage location for lipids in whales (blubber), acting as a heat insulator. Lipid in nerve cells act as an electrical insulator. Animals preparing for hibernation store extra fat.
What is buoyancy?
Because fat is less dense than water, it is used by aquatic mammals to help them afloat.
What is protection?
Humans have fat around delicate organs, such as their kidney’s to act as a shock absorber. The peptidoglycan cell wall of some bacteria is covered ina lipid rich outer coat.
