Membrane Structure

Question 1

Funktion of the plasma Membran

Answer 1

Act as a barriers
Prevent the contents of the cell from escaping and mixing the surrounding medium 
Involved in cell communication
Import export 
Cell growth and motility

Question 2

Internal membrane

Answer 2

Form many different compartments in a eukaryotic cell

Question 3

Lipid bilayer

Answer 3

Provides the basic structure for all cell membranes
The proteins on the Membran make the difference between the cells every cell have their one proteins which their functions

Question 4

The main phospholipid

Answer 4

Phosphoglycerin

Question 5

Phosphatidylglycerid

Answer 5

Phosphatidserin
Phosphatidylcholine
Phosphatidylinositol
Phosphatidyletanolamine

Question 6

The hydrophobic effect

Answer 6

Drives structural rearrangement of lipid

Question 7

Sealed compartment

Answer 7

A phospholipid bilayer spontaneously close to form a sealed compartment
Use the lowest energy

Question 8

Liposomes

Answer 8

Are bilayer made in the form of spherical vesicles

Question 9

Types of the movement that phospholipid molecules undergo

Answer 9

Flexion
Rotation
Lateral diffusion
Flip-flop (rarely occurs)

Move in their own mono layers
Lipid molecules do not move spontaneously from one monolayer to the other

Their are saturated and unsaturated tails … more short and unsaturated tails make the lipid layer more comfortable

Question 10

Cholesterol a sterol

Answer 10

Is found in large amount in eukaryotic plasma membranes

They control the movement of the lipid layer

Question 11

Membran Orientation

Answer 11

They retain their orientation during transfer between cell compartments
(Golgi-vesicles-membrane)

Question 12

Lipid asymmetrically

Answer 12

Phospholipid and glycolipid are distributed asymmetrical in the lipid bilayer

Lipid asymmetry is functionally important in order to convert extracellular signals in intracellular ones
One function of Glikolipids is that they work as receptors, they catch the signals and give them into the intracellular space

Question 13

Plasma membrane proteins Funktions

Answer 13

They have variety of funktions

Transporters and Channel (Na Pumps)
Anchors (intergrins)
Receptors (PDGF)
Enzymes(adenyl-cyclase)

Question 14

Association between membrane protein and lipid bilayer

Answer 14

1. Trans membran
2. Monolayer associated alpha helix
3. Lipid linked
4. Protein-attachend

Question 15

Trans membrane

Answer 15

Across the bilayer as a single alpha helix
Hydrophobic region interior of the bilayer
Hydrophilic region are exposed to the aqueous environment

Question 16

Monolayer associated alpha helix

Answer 16

Located almost entirely in the cytosol and are associated with the cytosolic half of the lipid bilayer by an amphipathic alpha helix

Question 17

Lipid linked

Answer 17

Lie entirely outside the bilayer on one side or the other, attached to the membrane only by one or more covalently attached lipid group

Question 18

Protein attached

Answer 18

They are bound indirectly to one or the other face of the membrane, held in place only by their interactions with other membrane proteins

Question 19

Most trans membrane protein

Answer 19

In most transmembrane protein the polypeptide chain crosses the lipid bilayer in a alpha helix conformation

Single pass transmembrane protein
Multi pass transmembrane protein

Question 20

Transmembrane hydrophilic pore

Answer 20

Can be formed by multiple amphipathic alpha helicas

Question 21

Beta sheets

Answer 21

Rolled up beta sheets (beta barrels)
Form large and rigid transmembrane channel
They carriers molecules that are water soluble

Question 22

Solubilize of Membran proteins

Answer 22

Membran proteins can be solubilized with a mild non ionic detergent
The hydrophobic part of detergent hint on the hydrophobic part of the protein or lipid

Question 23

Cell cortex

Answer 23

The plasma Membran is reinforced by underlying cell cortex
Under the plasma Membran are fiber proteins (cell cortex)
Exp. By erythrocytes they are dimerik protein spektrin

Question 24

Cortical cytoskeleton

Answer 24

Gives membranes mechanical strength and restricts Membran protein diffusion
Give erythrocytes to cross a very thin kapillar and have take their structure

Question 25

Fluorescence recovery after photobleaching

Answer 25

With FRAP the rate of lateral diffusion of a Membran protein can be measured

Question 26

Restriction of lateral mobility of specific plasma membran protein

Answer 26

1. Self assemble into large aggregates
2. Tethered by interaction with assemblies of macromal (outside the cell)
3. Tethered by interaction with assemblies of macromal (inside the cell)
4. Interact with proteins on the surface of another cell (epithelial cells in the gut)

Question 27

Glycosyated

Answer 27

Many Membran protein are glycosyated

Glikoprotein (short saccarid chain)
Proteoglikan(one or more long chain
Together build a glikokaliks

Cells with glikokaliks have a lot of functions
For example: to know infection regions