Lipids

Question 1

What are triglycerides made out of?

Answer 1

One mole glycerol with free fatty acids attached to it.

Question 2

What are the fatty acid molecules structured like?

Answer 2

contains long tails of hydrocarbon that are hydrophobic - they repel water. This then makes lipids insoluble in water. There is a carbon atom that links the fatty acid to glycerol. There is also a variable R group hydrocarbon tail.

Question 3

What are the two types of fatty acids?

Answer 3

Saturated and unsaturated fatty acids

Question 4

What is the differences between the hydrocarbon tails of saturated and unsaturated fatty acids?

Answer 4

Saturated fats - don’t have double bonds between carbon atoms.
Unsaturated fats - has at least one carbon double bond

Question 5

What is the difference between triglycerides and phospholipids?

Answer 5

In phospholipids one of the fatty acid molecules are replaced with a phosphate group, which is hydrophilic - attracts water. The fatty acids are still hydrophobic.

Question 6

What is the tests for lipids?

Answer 6

The emulsion test

Question 7

What is the steps for the test for lipids?

Answer 7

1. Add ethanol to the food sample and shake.
2. pour the solution into water
3. if there is any lipids present in the food sample a milky and motion will appear at the top of the water, the thicker the milky emotion the more lipids are present in the food

Question 8

How is a triglyceride formed?

Answer 8

A fatty acid interacts with a glycerol and H2O is released when the ester bonds have formed. This process has to happen twice in order to form the triglyceride

Question 9

What is the lipid found in the cell membrane?

Answer 9

The phospholipid

Question 10

Why do triglycerides make good energy storage molecules?

Answer 10

1.Their long hydrocarbon tails contain lots of chemical energy - energy released when they are broken down. These tails cause lipid to contain twice the energy than carbs.
2. They’re insoluble - doesn’t impact water potential. The triglycerides clump together as insoluble droplets in cells - the fatty acid tail is hydrophobic so they face inwards shields themselves from water with their glycerol heads.

Question 11

How does phoshpolipids help with the function of the cell membrane?

Answer 11

1. Their heads are hydrophilic and their tails are hydrophobic so they form a double layer with their heads facing out towards the water on either side.
2. The centre of the bilayer is hydrophobic so water soluble substances can’t easily pass through - the membrane act as a barrier to those substances.