Lipids Flashcards Preview

Biology > Lipids > Flashcards

Flashcards in Lipids Deck (12):

What makes up a lipid?

A high number of carbon and hydrogen atoms and a low number of oxygen atoms


What common features do lipids have?

- Insoluble in water
- soluble in alcohol
- not polymers, they are macromolecules as no repeating units


What is the structure of a triglyceride?

3 hydrocarbon chains derived from fatty acids that are ester bonded to one molecule of glycerol


What is an unsaturated fatty acid? How is it arranged?

- has one or more carbon carbon double bonds
- causes kinks in the chains so they cant pack tightly together
- this means more unsaturated fatty acids cause weak IMF / Van der Waals


What is a saturated fatty acid? How is it arranged?

- has no carbon carbon double bonds
- so chains pack tightly
- so strong IMF/ Van der Waals


What makes up the ester bond?

the carbon of the glycerol bonded to an oxygen bonded to a carbon, double bonded to an oxygen


What is the function of a triglyceride?

- Great energy source due to high ratio of c-h bonds
- great energy store as its insoluble, doesn't affect water potential
- provides heat and electrical insulation
- waterproofing
- protects organs


What is the structure of a phospholipid?

2 hydrocarbon chains derived from fatty acids that are ester bonded to one molecule of glycerol which is ester bonded to a phosphate group


What properties does a phospholipid have?

- it is amphipathic which means it has a hydrophobic tail and a hydrophilic head
- this causes it to form phospholipid bilayers and micelles in water
- it can form a fluid mosaic
-bacteria have more proteins in the membrane
- it is selectively permeable, only small non polar molecules can pass through it


What is cholesterol? Why is important?

- A steroid and a lipid
- contains no fatty acid or glycerol
- made of 4 isoprene units
- small and hydrophobic
- can sit in the hydrophobic layer of the phospholipid bilayer
- regulates fluidity
- made in the liver
- can make testosterone, oestrogen and vitamin D which can also pass through PBL


what is the test for lipids?

- shake sample with alcohol
- combine with water
- if it turns cloudy white then its positive


Why does the emulsion test produce a cloudy white substance?

- lipids are insoluble in water and soluble in ethanol
-After lipids have been dissolved in ethanol and then added to H2O, they will form tiny dispersed droplets in the water. This is called an emulsion.
-These droplets scatter light as it passes through the water so it appears white and cloudy.