Lipids Flashcards
What elements do lipids contain?
Carbon, hydrogen and a small amount of oxygen
What is structure of triglycerides?
One glycerol molecule with 3 fatty acid chains
What are the 4 properties of triglycerides?
- Insoluble in water (hydrophobic tails don’t interfere with water potential)
- soluble in some organic solvents e.g ethanol
- non polar
- hydrophobic
Give the state of lipid fats and lipid oils at room temperature.
Fats= solid
Oils=liquid
What are some of the functions of triglycerides? Go in to more detail for the main functions
- Energy source: broken down in respiration to release energy and generate ATP
- Energy store: insoluble in water so can be stored without it affecting the water potential of cells + hydrocarbon tails of fatty acids have lots of chemical energy which is released when broken down
- Thermal insulation: lipid around nerve cell acts as an electrical insulator
- Buoyancy: fat is less dense then water so is used by aquatic mammals to help them stay afloat
- Protection: fat around organs act as a shock absorber and in leaf cuticles
- Metabolic source of water
- Hormones
What is the structure of a glycerol molecule?
3 carbon molecule with three OH groups and 5 hydrogens bonded to carbon atoms
What is the structure of a fatty acid tail?
- has an acid group at one end (COOH)
- hydrocarbon chain (2 x 20 carbons long)
Describe and explain the difference between a saturated and unsaturated fatty acid.
- Saturated=all carbon atoms are joined by a single bond. All possible bonds are with hydrogen (fully used up)
- Unsaturated=there is at least one double bond between carbon atoms in the chain. Contains fewer hydrogen atoms bonded to the molecule therefore. The presence of the double carbon bonds changes the shape of the hydrocarbon chain and makes the molecules push apart, making them more fluid. E.g olive oil.
How can you tell from the formula of a molecule if it is saturated or unsaturated, and how many double bonds it does contain?
A saturated molecule’s formula would have exactly double the amount of hydrogens it does carbons. For e.g C18 H36 O2
An unsaturated molecule’s formula does not follow this rule. For e.g
C18 H32 O2 the hydrogen has a difference of 4 from being doubled (36) meaning that there is 4 less hydrogens, creating 2 double carbon bonds. This is known as being polyunsaturated.
What is esterfictaion?
A condensation reaction where an ester bond is formed between the glycerol and the fatty acid
What is the structure of a phospholipid?
Has a phosphate group head, glycerol molecule, and 2 fatty acid tails
How does the structure of a phospholipid relate to it’s function in membranes?
The phospholipids can form a monolayer (one row of phospholipids), micelle (circular formation) or form a phospholipid bilayer in the cell surface membrane. The bilayer is arranged with the hydrophilic heads on the outside (phosphate group has negative charge= attracted to water) and the hydrophobic fatty acid tails on the inside.
This arrangement allows for organisms to control the fluidity of their membranes.
What is the structure of cholesterol?
Small molecule made up of 4 carbon based rings, with a hydroxyl group one end, and one hydrocarbon tail the other end.
Explain how the structure and properties of cholesterol allows is to carry out its function in the cell membrane.
-small, narrow shape and hydrophobic nature it can sit amongst the hydrophobic hydrocarbon chains of the phospholipids in membranes. = this allows cholesterol to influence the fluidity and strength of the membrane
Cholesterol is also used for the production of steroid hormones and certain vitamins as their lipid nature allows them to pass freely through the phospholipid bilayer to reach target receptors
