Lesson 3-4

Question 1

What is the main components of cell (biological) membrane?

Answer 1

lipoids 40% and proteins 60%

Question 2

Important lipoids in the cell membrane:

Answer 2

Mainly phospolipids: sphingomyelin, lecithin, cephalin.

Cholesterol

Question 3

What is Glycerolphspatide?

Answer 3

If the phospholipids have a glycerol backbone

Question 4

What type of small molecules, usually polar can be linked to the phsophate group?

Answer 4

Lecithine and cephaline. Forms a variety of phospholipids

Question 5

Cephaline is:

Answer 5

if instead of choline there is a cholamine in the molecule

Question 6

Phosphatidic acid is:

Answer 6

When there is neither choline nor cholamine in the structure

Question 7

Sphingolipids is:

Answer 7

A phospholipid.

18-carbon amino alcohol with an unsaturated hydrocarbon chain.

Question 8

Ceramine is:

Answer 8

Sphingosine + fatty acid

Question 9

Sphingomyelin is:

Answer 9

Ceramide + phosphate + choline

Question 10

What is characteristic of an unsatturated fatty acid

Answer 10

Has generally one to three double bonds.
The fatty acid will have a kink in its shape wherever a double bond occurs that result in looser packing and lower melting points.

Question 11

What is the characteristics of cholesterol?

Answer 11

They are steroids.
they are characterized by a carbon skeleton consisting of four fused rings.
Function to stabilize the membrane.
Precursor from witch other steroids are synthesized.
High levels in blood = atherosclerosis.
(NOT in prokaryotes)

Question 12

Types of movement of lipids in the membrane:

Answer 12

• rotation
• lateral diffusion
• transversal diffusion (flip-flop)
  - energy is needed, flippase protein is needed.

Question 13

What is Integral proteins?

Answer 13

• Transmembrane proteins with hydrophobic regions that completely span the hydrophobic interior of the membrane.
• Dynamic function, serve as ion-channels.

Question 14

What is Peripheral proteins?

Answer 14

• loosely bound to the surface of the membrane (not embedded in the lipid bilayer)
  often to the exposed part of the integral proteins.
• static function, receptor function.

Question 15

What are the membrane carbohydrates?

Answer 15

• branched oligosaccharides with fewer than 15 sugar units (glucose, galactose, mannose, fucose = deoxyhexose and the N-acetylated sugars like N-acetylglucosamine, N-acetylgalactosamine and mannosamine + pyruvate = neuraminic acid.)
• glycolipids
• glycoproteins

Question 16

Oligosaccharides functions as?

Answer 16

markers that distinguish one cell from another.

Question 17

What is Lipid raft?

Answer 17

Spingolipid and cholestrol rich microdomain, ordered assemblies of specific proteins = lipid raft.
- important role in the cellular machinery

Question 18

Membrane fluidity (elasticity) increases if:

Answer 18

• increased temperature
• decreased amount of cholestrol
• increased proportion of cis-unsaturated fatty acids in the phospholipids.

Question 19

Describe Passive transport:

Answer 19

• Direction: down the concentration/electro chemical gradient.
• Energy: no
• Carrier: generally no (but at facilitated yes)
• Specific inhibition: no

Question 20

describe Active transport:

Answer 20

• Direction: Against concentration/electrochemical gradient.
• Energy: yes
• Carrier: yes
• Specific inhibition: yes

Question 21

Types of passive transport:

Answer 21

Simple diffusion, Facilitated diffusio, Osmosis

Question 22

Simple diffusion:

Answer 22

• Molecules can diffuse passively through the lipid components of cellular membranes.
• Oxygen, carbon dioxide, ammonia, ethanol, urea etc.

Question 23

Facilitated diffusion:

Answer 23

• Molecules can diffuse passively through proteins of cellular membranes which act as carrier and transport molecules or produce pores, gates.
• glucose, glucose transportes, carnitine and translocase

Question 24

Osmosis:

Answer 24

Transport of solvent throug the cellular membrnae from the less concentrated solution in the direction of more concentrated solution.

Question 25

Gibbs-Donnan-Equilibrium

Answer 25

Unequal ion distribution on both side of the semipermeable membrane –> membrane potential

Question 26

Types of active transport:

Answer 26

They differ in their source energy:

• Primary active transport: involves a transport protein that directly hydrolyzes ATP to drive the transport process
• Secondary active transport (cotransport): utilizes energy stores in electromechanical gradients of ions to drive transport.

Question 27

Types of primary active transport:

Answer 27

• Sodium-potassium pump
• Proton pump
  a) in the respiratory chain
  b) in the epithelial cells of stomach mucous membrane
• ABC transporter protein family

Question 28

Types of Secondary active transport:

Answer 28

• SGLT-1 and SGLT-2 transporters