Lipids - Recall

Question 1

What are the 3 types of lipids?

Answer 1

Triglycerides
Phospholipids
Sterols

Question 2

What is the structure of triglycerides?

Answer 2

Triglycerides are made up of glycerol connected to three fatty acid tails through ester bonds.

Question 3

What are the 5 functions of triglycerides?

HINT: E W A T P

Answer 3

HINT: Eager Whales Add Thick Padding

E - Energy: Lipids are a major source of energy.
W - Water: They are a source of metabolic water when oxidized.
A - Adipose Tissue: Lipids make up adipose tissue, storing fat in the body.
T - Thermal Insulation: They provide thermal insulation under the skin, especially in animals.
P - Protection: Lipids cushion and protect internal organs.

Question 4

How do triglycerides compare to carbohydrates in terms of energy?

Answer 4

-Per g triglycerides release more energy

Question 5

Being a source of metabolic water makes them useful for organisms in what kind of environment?

Answer 5

Desert

Question 6

Give an example of an animal that uses triglycerides as thermal insulation

Answer 6

Killer whale in the form of blubber

Question 7

When are triglycerides stored as adipose tissue?

Answer 7

When energy input is greater than energy output

Question 8

Why is cholesterol transported as a lipoprotein?

Answer 8

They allow lipids and cholesterol to dissolve in the blood

Question 9

What are the functions of sterols (2 functions)?

Answer 9

Cholesterol used in cell membranes to give stability and regulate fluidity
Used to make steroid hormones

Question 10

Give 2 examples of steroid hormones

Answer 10

Testosterone and oestrogen

Question 11

Where is cholesterol manufactured?

Answer 11

The liver and intestines

Question 12

What is the function of HDL?

Answer 12

used to make cell membranes and organelle membranes
decreases membrane fluidity

Question 13

Which is ‘good’ cholesterol; HDL or LDL?

Answer 13

HDL

Question 14

What does too much LDL lead to?

Answer 14

atherosclerosis (deposits in artery walls)
gall stones

Question 15

How are triglycerides formed?

Answer 15

A condensation reaction between a glycerol molecule and 3 fatty acids

Question 16

What kind of bonds are formed when a triglyceride is formed?

Answer 16

Ester bonds

Question 17

Which part of a glycerol molecule takes part in the condensation reaction to form a triglyceride?

Answer 17

The hydroxyl groups

Question 18

What is the structure of a glycerol molecule?

Answer 18

C3H5(OH)3

Question 19

How many molecules of water are formed from the condensation reaction to form a triglyceride?

Answer 19

3

Question 20

What does a hydrolysis reaction of a triglyceride produce?

Answer 20

A glycerol molecule and 3 fatty acids

Question 21

How are phospholipids formed?

Answer 21

A condensation reaction between a glycerol molecule, 2 fatty acids, and a phosphate group

Question 22

What kind of bonds are formed in phospholipids?

Answer 22

Ester bonds

Question 23

What property does the head of a phospholipid have?

Answer 23

It is hydrophillic and polar

Question 24

What property does the tail for a phosphlipid have?

Answer 24

It is hydrophobic and non-polar

Question 25

Explain the differences between phospholipids and triglycerides. HINT: Three Fat Triggers, Two Fancy Phos

Answer 25

Three Fat Triggers: Triglycerides have 3 fatty acids. They also have 3 ester bonds. Two Fancy Phos: Phospholipids have 2 fatty acids and 1 phosphate group. They form a hydrophilic head (thanks to the phosphate group).

Question 26

Draw a simplified version of a phospholipid

Answer 26

head + two tails

Question 27

Draw a phospholipid bilayer

Answer 27

hydrophilic phosphate heads on the outside + hydrophobic fatty acid tails in the middle (hydrophobic core forms in the middle)

Question 28

Explain why membranes exist as bilayers HINT: All Bears Hate Honey

Answer 28

A - Aqueous environments: Inside (cytoplasm) and outside (tissue fluid) the cell are watery environments. B - Bilayer: A bilayer forms because a single layer wouldn’t work (it would repel water on one side). H - Hydrophilic heads: The hydrophilic (water-loving) heads face outward toward the aqueous environments. H - Hydrophobic tails: The hydrophobic (water-fearing) tails hide inward, away from the water.

Question 29

How does cholesterol sit in phospholipid bilayers?

Answer 29

With the hydroxyl group in contact with the Phosphate head

Question 30

What are sterols made up of?

Answer 30

Large alcohol molecules

Question 31

What happens to membrane fluidity, when cholesterol increases?

Answer 31

Decreases

Question 32

What happens to membrane fluidity, when cholesterol decreases?

Answer 32

Increases

Question 33

How can you test for the presence of lipids?

Answer 33

Add ethanol first and then the resulting mixture add to water and shake

Question 34

State two roles of cholesterol in living organisms

Answer 34

1) Increases stability of phospholipds in cell membrane 2) Waterproofing to skin

Question 35

Name two molecules that combine with cholesterol to form LDLs

Answer 35

1) Saturated fatty acids 2) Triglycerides/lipids