Lipids

Question 1

What are lipids?

Answer 1

biological molecules that are generally insoluble in water

Question 2

What can lipids be divided into?

Answer 2

Simple - after hydrolysis a maximum of 2 products are produced
Complex - 3 or more products produced

Question 3

How are lipids classified?

Answer 3

By structure or by function

Question 4

What are storage lipids?

Answer 4

Fats and oils used as stored forms of energy are derivatives of fatty acids

Question 5

What are fatty acids?

Answer 5

Carboxylic acids with hydrocarbon chains (4-36 carbons)

Question 6

What is a saturated hydrocarbon chain?

Answer 6

chain with no double carbon bonds

Question 7

What does the systematic name of fatty acids include?

Answer 7

Specifies the chain length and number of double bonds

Question 8

What are triglycerols (triacylglycerols)?

Answer 8

fatty esters of glycerol - 3 fatty acids with a single glycerol molecule

Question 9

Are triglycerols hydrophilic or hydrophobic?

Answer 9

hydrophobic

Question 10

What are waxes made out of?

Answer 10

Esters of long chain saturated or unsaturated fatty acids with long chain alcohols

Question 11

Name some general types of membrane lipids

Answer 11

Glycerophospholipds: 2 fatty acids esterified to G3P
Galactolipds and sulpholipids
Archaeal tetraether lipids
Sphingolipids
Sterols

Question 12

List some features of the phospholipid bilayer

Answer 12

Very low permeability (except water)
permeable to small molecules
need transport proteins

Question 13

What are some limitations of the phospholipid bilayer?

Answer 13

oversimplified and generalised diagrams

descriptions focus on plasma membrane of mammals

Question 14

Where are galactolipids found?

Answer 14

chloroplast membranes

Question 15

What do sulpholipids contain?

Answer 15

sulphonated glucose instead of galactose

Question 16

Where are sulpholipids found?

Answer 16

In plants, algae and cyanobacteria

inner membranes of chloroplasts

Question 17

What is one of the most common sulpholipids in plants and algae?

Answer 17

Sulphoquinvosyl dipalmitoylglycerol (SQDG)

Question 18

What structure synthesises lipids?

Answer 18

Mitochondria

Question 19

What do membranes have a high content of?

Answer 19

Phospholipids

Question 20

Where is Cardiolipin found?

Answer 20

Inner mitochondrial membrane

Question 21

What are sphingolipids made out of?

Answer 21

1 molecule of fatty acid and sphingosine instead of glycerol

polar head and 2 non-polar tails

Question 22

What are the 3 sphingolipid subclasses?

Answer 22

Shphingomyeline, glycosphingolipids, gangliosides

Question 23

What is the function of flippases and floppases in a phospholipid bilayer?

Answer 23

Move specific phospholipids against their conc gradient using ATP

Question 24

What molecules do flippases move across the membrane?

Answer 24

Aminophospholipds and phosphatidylethanolamine from outer in inner against conc gradient

Question 25

What molecules do floppases move across the membrane?

Answer 25

Phosphatidylcholine, sphingolipid and cholesterol against their conc gradients

Question 26

What is the function of scramblases?

Answer 26

Facilitate movement of lipids along their concentration gradients without use of ATP

Question 27

During apoptosis what is the function of aminophospholipids (AP)?

Answer 27

Activation of scramblases allows rapid appearance of AP on the outer surface of plasma membrane where it provides “eat me” signal

Question 28

Name the three types of Eicosanoids that produce extracellular signals

Answer 28

Prostaglandins, Thromboxanes and Leukotrienes

Question 29

What do prostaglandins produce extracellular signals for?

Answer 29

Contraction of smooth muscle, fever and inflammation

Question 30

What do thromboxjnes produce extracellular signals for?

Answer 30

Formation of blood clots

Question 31

What do leukotrienes produce extracellular signals for?

Answer 31

Contraction of smooth muscle lining in airways to the lungs

Question 32

What are steroid hormones derivatives of?

Answer 32

Sterols (include sex hormones and glucocorticoids)

Question 33

What do steroid hormones do?

Answer 33

Circulate in the blood stream bound to carrier proteins and trigger changes in gene expression

Question 34

What intracellular signal is released under conditions of stress?

Answer 34

Shingomyelinases