Lecture 15/16 - Lipid and Cell Membrane Structure

Question 1

What are the main components of a fatty acid?

Answer 1

• hydrocarbon chain

- terminal carboxyl group

Question 2

Differentiate between saturated and the types of unsaturated fatty acids.
(Melting point and flexibility)

L15/16 S6

Answer 2

Saturated:

• no double bonds
• higher melting point
• more flexible

Cis-unsaturated:

• cis-double bond (less bent than trans)
• lower melting point
• less flexible

Trans-unsaturated:

• trans-double bond (more bent than cis)
• lower melting point
• less flexible

Question 3

How are omega fatty acids named?

L15/16 S18

Answer 3

Position of the closest double bond the the omega methyl group.

Question 4

What are the examples of omega-3 and omega-6 fatty acids?

L15/16 S18

Answer 4

Omega-3:

• linolenic acid (18:3)/ALA
• stearidonic acid (18:4)/SDA
• docosapentaenoic acid (22:5)/DPA
• eicosapentaenoic acid (20:5)/EPA
• docosahexaaenoic acid (22:6)DHA

Omega-6:

• linoleic acid (18:2)/LA
• aarachidonic acid (20:4)/AA
• docosapenaenoic acid(22:5)/DPA

Question 5

What is the significance of omega fatty acids?

L15/16 S19

Answer 5

• used in cell membranes
• energy source
• good for cardiovascular health

Question 6

What omega fatty acids can humans not synthesize and what amino acids are synthesized by converting another omega fatty acid?

L15/16 S19

Answer 6

Can’t synthesize:

• LA/linoleic acid (18:2)/ω-6
• ALA/linolenic acid (18:3)/ω-3

Converted (both from ALA):

• EPA (20:5)/ω-3
• DHA (22:6) ω-3

Question 7

What is the structure of triacylglycerols (TAGs)?

L15/16 S20

Answer 7

3 hydrophobic fatty acid chains attached to a polar glycerol

Question 8

What is the structure of a wax?

L15/16 S22

Answer 8

Fatty acid attached to an alcohol

Question 9

What is special about lipids in archaea membranes?

L15/16 S23

Answer 9

They contain branched fatty acids

Question 10

What are the three categories of cell membrane lipids?

L15/16 S24

Answer 10

• phospholipids
• glycolipids
• cholesterol

Question 11

What is the structure of phospholipids?

L15/16 S26

Answer 11

Glycerol with two fatty acids and a phosphate group attached.

The phosphate group has an alcohol attached.

Question 12

What are the most common alcohols attached to phosphates of fatty acids?

L15/16 S27

Answer 12

Amino acids:
-serine

Sugar-alcohols:

• inositol
• glycerol

Organics:

• ethanolamine
• choline

Question 13

What are sphinomyelins?

L15/16 S28

Answer 13

They attach fatty acids to an amine group

Question 14

What is the significance of glycosphingolipids?

L15/16 S29-30

Answer 14

They are responsible for ABO blood types

Question 15

What is cholesterol?

L15/16 S32

Answer 15

Polar sterol that can insert into cell membranes and add rigidity