Lectures 15-16: Lipid and Cell Membrane Structure

Question 1

What are the basics of the structure of a fatty acid?

Answer 1

Hydrocarbon+carboxyl

Primary HYDROPHIBIC determinant

can be saturated or unsaturated (double bond)

Question 2

Describe a fatty acid who melts at a lower boiling point and is not very flexible

Answer 2

Unsaturated

Question 3

What is the relationship between the length of a fatty acid and the temperature at which it melts?

Answer 3

Proportional: Shorter fatty acids melt at lower temperature

Question 4

Describe all of the necessary components that are needed in order to name a fatty acid

Answer 4

1. need to know if it is cis or trans
2. need to know if there are any double bonds in the molecule and what carbons they are between
3. the number of the hydrocarbon chain
4. level of saturation
5. what functional groups are in the fatty acid

Question 5

If you have a fatty acid that is deprotonated, what will the suffix of that molecule be?

Answer 5

-oate

Question 6

How many carbons and double bonds is in stearate?

Answer 6

18:0

Question 7

How many carbons and double bonds is in Oleate?

Answer 7

18:1

Question 8

How many carbons and double bonds is in Linoleate?

Answer 8

18:2

Question 9

How many carbons and double bonds is in Linolenate?

Answer 9

18:3

Question 10

How do you tell the difference between Omega 3 fatty acids and Omega 6 fatty acids?

Answer 10

By where the double bonds are positioned in the molecule

3 vs. 6

Question 11

List the Omega 3 fatty acids

Answer 11

Linolenic Acid 
Stearidonic Acid 
Docosapentaenoic Acid 
Eicosapentaenoic Acid 
Docosahexaenoic Acid

Question 12

Define ALA

Answer 12

Linolenic Acid (18:3)

Question 13

Define SDA

Answer 13

Stearidonic Acid (18:4)

Question 14

Define DPA

Answer 14

Docosapentaenoic Acid (22:5)

Question 15

Define EPA

Answer 15

Eicosapentaenoic Acid (20:5)

Question 16

Define DHA

Answer 16

Docosahexaenoic Acid (22:6)

Question 17

Define LA

Answer 17

Linoleic Acid (18:2)

Question 18

Define AA

Answer 18

Archidonic Acid (20:4)

Question 19

What are the two omega acids that cannot be synthesized by humans?

Answer 19

LA (18:2/w6)

ALA (18:3/w3)

Question 20

What are the two fatty acids that ALA can be converted into? (inefficiently)?

Answer 20

EPA( 20:5/w3)

DHA (22:6/w3)

Question 21

Why are omega fatty acids important?

Answer 21

• Used in the cell membrane and other important lipids
• are a common energy source
• promote good health via CV

Question 22

Describe triacylglycerols

Answer 22

have 2 parts, polar head of glycerol and hydrophobic tail that is made up of 3 fatty acid chains

Question 23

Describe waxes

Answer 23

They have a polar head of alcohol and a hydrophobic tail made up of fatty acids chains

Question 24

What are the 3 categories of cell lipid membranes?

Answer 24

1. phospholipids
2. glycolipids
3. cholesterol

Question 25

Describe the structure and function of glycerophospholipids

Answer 25

make up the majority of the cell membranes; include a hydrophilic group, a phosphate, glycerol, and fatty acids

Question 26

What are the common alcohols that are added to glycerophospholipids? 1. amino acid 2. sugar alcohols 3. organics

Answer 26

1. serine 2. inositol, glycerol 3. ethanol amine, choline

Question 27

Describe sphingomyelin

Answer 27

fatty acid attached to an amine

Question 28

Why are glycoshingolipids important?

Answer 28

ABO blood type antigens cell signaling

Question 29

Describe carbohydrates in the membrane

Answer 29

they "decorate" lipids and proteins but are only on the surface, and not in contact with the cytosol at all

Question 30

Describe integral membrane proteins

Answer 30

have hydrophobic amino acids that can create a hydrophobic environment; they span the bilayer They can insert via cotranslational insertion, which involves a ribosome and a translocon channel that is able to insert and fold the protein into the membrane

Question 31

Describe peripheral proteins

Answer 31

span only PART of the lipid bilayer and their anchors are hydrophobic soluble proteins are able to associate with the membrane IF the hydrophobic groups are attached to the proteins

Question 32

What are the functions of membrane proteins ?

Answer 32

1. receive external signals 2. transmit in 3. transmit to another cell 4. let solutes pass 5. determine the thickness and rigidity

Question 33

Describe the concept of lateral diffusion as it relates to membrane proteins

Answer 33

The membrane proteins are always in lateral motion, the fluid mosaic model allows lateral movement but no rotation, so she's always hula dancing almost

Question 34

Compare the rigidity between human and bacteria membranes

Answer 34

in bacteria, the rigidity is determined by the fatty acid composition in humans its all about the cholesterol (can combine to make lipid rafts)