LGS A-Level OCR Biology - Unit 2 - Lipids
The three main types of lipids are triglycerides, phospholipids, and sterols. Triglycerides act as energy stores, phospholipids form cell membranes, and sterols (like cholesterol) help regulate membrane fluidity and serve as precursors for hormones.
What are the 3 types of lipids?
Triglycerides
Phospholipids
Sterols
Key Terms
What are the 3 types of lipids?
Triglycerides
Phospholipids
Sterols
What are the 5 functions of triglycerides?
Major source of energy
Source of metabolic water
Makes up adipose tissue
provides thermal insulation under skin of animals
...
How do triglycerides compare to carbohydrates in terms of energy?
-Per g triglycerides release more energy
Being a source of metabolic water makes them useful for organisms in what kind of environment?
Desert
Give an example of an animal that uses triglycerides as thermal insulation
Killer whale in the form of blubber
When are triglycerides stored as adipose tissue?
When energy input is greater than energy output
Related Flashcard Decks
Study Tips
- Press F to enter focus mode for distraction-free studying
- Review cards regularly to improve retention
- Try to recall the answer before flipping the card
- Share this deck with friends to study together
| Term | Definition |
|---|---|
What are the 3 types of lipids? | Triglycerides Phospholipids Sterols |
What are the 5 functions of triglycerides? | Major source of energy Source of metabolic water Makes up adipose tissue provides thermal insulation under skin of animals Provides protection around internal organs |
How do triglycerides compare to carbohydrates in terms of energy? | -Per g triglycerides release more energy |
Being a source of metabolic water makes them useful for organisms in what kind of environment? | Desert |
Give an example of an animal that uses triglycerides as thermal insulation | Killer whale in the form of blubber |
When are triglycerides stored as adipose tissue? | When energy input is greater than energy output |
Why is cholesterol transported as a lipoprotein? | They allow lipids and cholesterol to dissolve in the blood |
What are the functions of sterols (2 functions)? | -Cholesterol used in cell membranes to give stability and regulate fluidity -Used to make steroid hormones |
Give 2 examples of steroid hormones | Testosterone and oestrogen |
Where is cholesterol manufactured? | The liver and intestines |
What is the function of HDL? | -used to make cell membranes and organelle membranes -decreases membrane fluidity |
Which is ‘good’ cholesterol; HDL or LDL? | HDL |
What does too much LDL lead to? | -atherosclerosis (deposits in artery walls) -gall stones |
How are triglycerides formed? | A condensation reaction between a glycerol molecule and 3 fatty acids |
What kind of bonds are formed when a triglyceride is formed? | Ester bonds |
Which part of a glycerol molecule takes part in the condensation reaction to form a triglyceride? | The hydroxyl groups |
What is the structure of a glycerol molecule? | |
How many molecules of water are formed from the condensation reaction to form a triglyceride? | 3 |
What does a hydrolysis reaction of a triglyceride produce? | A glycerol molecule and 3 fatty acids |
i) How are phospholipids formed? ii) What kind of bonds are formed? | i) A condensation reaction between a glycerol molecule, 2 fatty acids, and a phosphate group ii) Ester bonds |
What property does the head of a phospholipid have? | It is hydrophillic and polar |
What property does the tail for a phosphlipid have? | It is hydrophobic and non-polar |
Explain the differences between phospholipids and triglycerides | -Triglycerides contain 3 fatty acids but phospholipids only contain two and a phosphate group - Triglycerides contain 3 ester bonds but phospholipids only contain 2 - Phospholipids have a hydrophilic head |
Draw a simplified version of a phospholipid | |
Draw a phospholipid bilayer | |
Explain why membranes exist as bilayers | -Both the inside and outside of cells are aqueous -therefore a single layer would repel on one side -Bilayers mean that hydrophilic heads can face into the tissue fluid and cytoplasm -with the hydrophobic tails facing away from the aqueous environments |
How does cholesterol sit in phospholipid bilayers? | With the hydroxyl group in contact with the Phosphate head |
What are sterols made up of? | Large alcohol molecules |
As cholesterol increases membrane fluidity ____ | Decreases |
A decrease in cholesterol ____ fluidity | Increases |
How can you test for the presence of lipids? | Add ethanol first and then the resulting mixture add to water and shake |
State two roles of cholesterol in living organisms | 1) Increases stability of phospholipds in cell membrane 2) Waterproofing to skin |
Name two molecules that combine with cholesterol to form LDLs | 1) Saturated fatty acids 2) Triglycerides/lipids |