Lecture 2: Introduction to cellular membranes

Question 1

Membranes are composed of

Answer 1

lipids

Question 2

Overton (1980)

Answer 2

Dipped hair root in liquid, found that nonpolar solutes were more rapidly taken into the plant root hair as it was hdrophobic due to the membrane.

Question 3

Gorter and Grendel (1925)

Answer 3

Showed that lipids extracted from a red blood cell (no other internal membrane bound organelles) membrane could cover the cell twice. Membranes are bilayer.

Question 4

Membranes contains a bilayer of

Answer 4

phospholipids

Question 5

Amphipathic

Answer 5

Both polar and nonpolar

Question 6

Lipid bilayer prevents

Answer 6

random movements of substances in and out of the cell

Question 7

Fatty Acids

Answer 7

long, unbranched hydrocarbon chains

Question 8

Saturated

Answer 8

Lack double bonds

Question 9

Unsaturated (2)

What it is+structure

Answer 9

• contains one or more double bonds
• introduces a bend in the fatty acid

Question 10

Naturally occuring fatty ascids have — double bonds

Answer 10

cis

Question 11

Phosphoglycerides are

Answer 11

phospholipids

Question 12

Some sphinogolipids are

Answer 12

phospholipids

Question 13

Phosphoglycerides (4)

membrane+backbone+components+often contains

Answer 13

• most membrane phospholipids are phosphoglycerides
• Built on a glycerol backbone
• Glycerol+2 fatty acid chains+phophate group+ additional group
• often contains one unstaturated and one saturated fatty acid chain

Question 14

Overall charge for phosphatidic acid

Answer 14

-

Question 15

Overall charge for phosphatidylcholine

Answer 15

neutral

Question 16

Overall charge for phosphatidylserine

Answer 16

-

Question 17

Phosphatidylethanolamine

Answer 17

neutral

Question 18

Overall charge for phosphatidylinositol

Answer 18

-

Question 19

Membrane lipids (3)

Answer 19

• phosphoglycerides
• sphingolipids
• cholesterol

Question 20

Sphingolipids (6)

quanitity+what is it+property+head groups+fatty acid chain+roles

Answer 20

• less abundant membrane lipid
• built on sphingosine
• amphipathic
• additional groups can be linked to the head group
• Tend to have longer and more highly saturated fatty acid chains than phophoglycerides
• Roles in signal transduction, membrane structure, sensing

Question 21

Ceramide (2)

Answer 21

• Example of sphingolipid
• spingosine+fatty acid

Question 22

Spingolipids, if the addition is a carbohydrate, the molecule is a

Answer 22

glycolipid

Question 23

Glycolipids, 2 subcategories:

Answer 23

A cerebroside: Carb addition of a simple sugar with ceramide
A ganglioside: Carb addition of a complex carbohydrate with ceramide

Question 24

Membranes in the nervous system have a high abundance of

Answer 24

glycosphingolipids

Question 25

Tay-sachs disease

Answer 25

Deficiency of the enzyme that normally breaks down GM2 ganglioside. Excess GM2 builds up in the brain and impairs the function of nerve cells

Question 26

Membrane carbohydrates

% of the bonds

Answer 26

• 10% of membrane carbohydrates are covalently linked to lipids (glycolipids)
• 90% of membrane carbohydrates are covalently linked to proteins (glycoproteins)

Question 27

All membrane carbohydrates in the plasma membrane face the

Answer 27

extracellular space

Question 28

Myelin sheath is composed of

Answer 28

multiple layers of plasma membrane, with very little protein