Properties of Cell Membranes

Question 1

___ Are Mosaics

Answer 1

Membranes

Question 2

Eukaryotic Membranes Contain

Answer 2

• Lipid bilayer matric: Hydrophobic!
• Intrinsic and Extrinsic Proteins
• Glycolipids and Glycoproteins

Question 3

Function of Membrane

Answer 3

• Serve as reactive surface
• Serve to compartmentalize the cell
• Serve to control entry and exit of molecules

Question 4

Peripheral Proteins are noncovalently bonded to…

Answer 4

Integral Proteins

Question 5

Most integral membrane proteins have membrane-spanning alpha-helical domains of about __ amino acids

Answer 5

20

Question 6

Some integral proteins have multiple…

Answer 6

membrane-spanning domains

Question 7

Some proteins are linked to membrane phospholipids via…

Answer 7

an oligosaccharide

Question 8

2 main types of entry and exit mechanisms

Answer 8

Passive and Active

Question 9

Passive diffusion is a critical mechanism to move molecules…

Answer 9

into and out of the cell

Question 10

Write out FICK’s law for movement of a solute through a solution only

Answer 10

Ji=DiA(C1-C2)/x

J=Molar Flux of i
(mol/cm^2-sec)
D= Diffusion coefficient of i
A=Area over which diffusion takes place
(C1-C2)= Concentration gradient 
x=distance over which diffusion takes place

Question 11

Main movement through the membrane

Answer 11

• Unidirectional flux in, minus flux out
• Pore (non-gated channel)
• Channel (gated pore)

Question 12

___ can be active or passive

Answer 12

Carrier Mediated Transports

Question 13

The flux of transporter proteins reach a __-

Answer 13

Maximum Level (JMax)

Question 14

Example of Active Transport

Answer 14

Na/K Pump

3 Na+ Out for 2 K+ In
-Pump is electrogenic

Question 15

Michaelis-Menten Kinetics

Answer 15

Km

Jmax (Vmax)

Question 16

Name an example of a cell with multiple transport mechanisms whose function is to pass nutrients from the lumen of the gut to the blood.

Answer 16

The gut epithelial cell

Question 17

What happens in gut upon eating a meal?

Answer 17

Upon eating a meal: Na and
glucose concentrations
increase in gut.

Question 18

The serotonin transporter is an example of

Answer 18

of a protein with facilitated diffusion properties whose function is to clear neurotransmitter from the synaptic cleft of brain cells.

Question 19

____are a special type of transport mechanism - with characteristics of both passive diffusion and carrier mediated diffusion.

Answer 19

Ion Channels

Question 20

Ion channels demonstrate…

Answer 20

selectivity based

on the size of the channel opening

Question 21

Types of channels include…

Answer 21

Voltage gated
Ligand gated
Pressure/stretch gated
Non-gated (passive leak)
Water channel (aquaporins)

Question 22

Ion Channel Structure

Answer 22

• The ion channel structure is derived from the primary amino acid sequence.
• It consists of multiple subunits, each with distinct trans-membrane segments (domains) that fulfill distinct roles.

Question 23

What is Patch Clamp

Answer 23

recording technique for a single channel

Question 24

Flux and Direction is determined by…

Answer 24

Driving Force (voltage)

Question 25

What is resting membrane potential?

Answer 25

(dynamic balance between K and Na leakage )

Question 26

what happens when membrane potential is- More positive/ More negative

Answer 26

Depolarized/hyperpolarized