3.1.3 Lipids Flashcards
What are the main characteristics of Lipids?
- All contain Carbon, Hydrogen and Oxygen in small proportions
- Thye are insoluble in water
- They are soluble in organic solvents
What are the four main roles of lipids?
- Energy Source - Provide lots of energy
- Waterproofing - Lipids are insolube in water therefore a waxy layer on plants and animals
- Insulation - Fats are slow heat conductors and therefore retain body heat easily
4.Protection - Around delicate organs like the kidney
What are the two types of Lipids?
Triglycerides and Phospholipids
What is the structure of Triglycerides?
One glycerol molecule and Three fatty acids
How do triglycerides form?
Three condensation reactions between the fatty acids and the glycerol
This also forms three water molecules
What is a Saturated Fatty Acid?
Fatty acids that do not contain a double bond
What is an Unsaturated Fatty Acid?
Fatty acids that do contain a double bond between two carbon atoms
What happens to the shape of the chain in a polyunsaturated fatty acid?
The chain begins to curve at ever C-C double bond
How are triglycerides good energy-storing molecules?
Excellent store of energy due to them having a high number of energy-storing C-H bonds
How are triglycerides good energy storers?
They have a low mass to energy ration, making them good storage molecules because lots of energy can be stored in a small volume.
Are triglycerides insoluble in water?
Yes
Due to them being large and non-polar they do not affect the water potential of cells
What are phospholipids made up of?
One Phosphate Group
One Glycerol
Two Fatty Acids
What does hydrophobic mean?
Repels water
What does hydrophilic mean?
Attracts water
In a phospholipid, what is hydrophobic and hydrophilic?
The phosphate group is hydrophilic
The Fatty acid chains are hydrophobic
Are phospholipids non-polar?
No phospholipids are polar molecules
When are phospholipids found?
In cell membranes
What are micelles?
A tiny sphere where the outside is hydrophilic and the inside is hydrophobic
How does the phospholipid structure relate to its function?
- Due to the hydrophilic and hydrophobic nature of phospholipids, they can form a bilayer in aqueous solution. As a result, a hydrophobic barrier is formed between the inside and outside of a cell
- The phospholipid structure allows them to form glycolipids by combining with carbohydrates which are used in cell recognition
- In bilayers, phospholipids stop large water-soluble molecules from getting in
What is the test from lipids?
- Add 2cm^3 of sample to the test tube
- Add 5cm^3 of ethanol to the test tube
- Add 5cm^3 of cold water to the test tube
- Shake the test tube
- White emulsion should form
