1.23 - Lipids Flashcards
What are lipids used for?
They form a large part of the cell membrane and are used as an energy store
What defines a fat?
It is solid at room temperature
What defines an oil?
It is liquid at room temperature
What is different between lipids and carbohydrates?
Lipids contain far less oxygen
What makes a fatty acid?
A hydrocarbon “tail” with a carboxyl group(-COOH) at one end
What is an unsaturated fatty acid?
A fatty acid that contains at least one C=C bond
What is a saturated fatty acid?
A fatty acid that contains no C=C bonds
How is a lipid formed?
When a glycerol combines with at least one fatty acid
What bonds join the groups of a lipid?
Ester bonds
Where do ester bonds form?
Between the carboxyl group(-COOH) of a fatty acid and the hydroxyl(-OH) group of a glycerol
What reaction occurs to form an ester bond?
Condensation reaction
How much more energy do lipids store in comparison to carbohydrates?
About three times as much
What are some functions of lipids?
- Energy source
- Flexibility of the plasma membrane
- Protection
- Insulation
- Waterproofing
Why are triglycerides good energy stores?
The long hydrocarbon “tails” of the fatty acids contain lots of energy
What is the test for lipids?
The emulsion test
Describe the emulsion test
- Shake sample with ethanol until dissolved
- Pour solution into water
- Lipids will appear as a milky emulsion
What is the structure of a phospholipid?
A glycerol molecule bonded to two fatty acids and a phosphate
What is important about phospholipids?
They contain a hydrophobic tail and a hydrophilic head
What is a spherical arrangement of phospholipids called with the fatty acids facing inwards?
A micelle
How do phospholipids contribute to cell membranes?
They form a bilayer that can control what passes through