1.7 Lipids: Triglycerides & Phospholipids Flashcards
The structure and function of triglycerides The synthesis and breakdown of triglycerides The structure and function of phospholipids The similarities and differences between triglycerides and phospholipids
What is a triglyceride?
i.e what is it used for? and in what?
- A lipid
- used to store energy
- animals, plants, and some bacteria
What is the structure of a triglyceride?
Glycerol backbone and three fatty acid tails
What type of bonds are in a triglyceride?
Ester bonds
Why are 4 reasons why triglycerides good for energy storage?
- Long hydrocarbon tails - Many carbon-hydrogen bonds can be broken to release energy
- low mass to energy ratio - Lots of energy can be stored in a small volume
- Insoluble - Do not affect water potential of cells as they are large and non-polar
- High ratio of hydrogen to oxygen atoms - will release water when oxidised
How are triglycerides formed?
By condensation reactions
How are triglycerides broken down?
By hydrolysis reactions
What is a phospholipid?
A lipid used as a structural component of cell membranes
How does a phospholipid differ from a triglyceride?
One fatty acid tail is replaced by a phosphate group
What are the two parts of a phospholipid?
Hydrophilic head and hydrophobic tail
Why is the phospholipid head hydrophilic?
It contains a polar phosphate group
Why is the phospholipid tail hydrophobic?
It contains non-polar fatty acids
What is a phospholipid bilayer?
A double layer of phospholipids in water
How do phospholipids arrange in a bilayer?
Hydrophilic heads face outwards
Why does a phospholipid bilayer form a barrier?
The hydrophobic center repels water-soluble substances
What is the function of triglycerides?
Energy store
What is the function of phospholipids?
Structural component of membrane
How many fatty acid tails do triglycerides have?
3
How many fatty acid tails do phospholipids have?
2
Do triglycerides contain phosphate?
No
Do phospholipids contain phosphate?
Yes
Are triglycerides polar or nonpolar?
Non-polar
Are phospholipids polar or nonpolar?
Polar
