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Flashcards in Chapter 5 - Lipids Deck (10):

Define: Lipids

Lipids are grouped with each other because they mix poorly with water.

They are the one class of large biological molecules that does not include true polymers.

The hydrophobic behavior of lipids is based on their molecular structure.


What are the three different types of lipids that are most biologically important?



What is a fat molecule made up of?

Glycerol (an alcohol)
Three fatty acids (aka triacylglycerol)


Explain a saturated fat.

If there are no double bonds between carbon atoms composing a chain, then as many hydrogen atoms as possible are bonded to the carbon skeleton. (Saturated fats is a solid and will try to get as much hydrogen as possible)

Ex. Butter


Explain an unsaturated fat

An unsaturated fat will have double Bond in it. Usually it becomes an unsaturated fat because there is a cis isomer in the bonding of molecules (which causes a bend, which causes them to not be able to pack closely together enough to solidify)

Side note: You can treat it to make a trans isomer but trans isomers can only be made. It cannot be found naturally.


What is a trans fat?

Trans fats are usually made not found naturally. They are very unhealthy. Most baked goods and processed foods contains trans fats.

May contribute more to atherosclerosis


What is the function of fats?

Energy storage; a gram of fat stores more than twice as much energy as a gram of a polysaccharide like starch.


What are the other kinds of fats? (As listed in the power point)

Trans fats
Hydrogenated unsaturated fat
Omega-3 fatty acids - double Bond at the third carbon; carbon bond form end of hydrocarbon chain.


What is a phospholipid?

Make up cell membranes
It is similar to a fat but only has two fatty acids.
3rd hydroxyl group of glycerol is joined with a phosphate group
They have a hydrophilic head and hydrophobic tails. (In a cell membrane it does not let outside water in)


What are steroids?

- They are characterized by a carbon skeleton consisting of four fused rings.
- Different steroids will have different functional groups
- Cholestrol is a type of steroid and it is a crucial molecule in animals.
- Estrogen and testosterone