Transmembrane Transport and Membrane Potential

Question 1

which of the following is NOT correct about the Categories of Transport Across the Cell Membrane?

A. Cell membrane is selectively permeable to some molecules and ions.
B. it’s mainly not permeable to proteins, nucleic acids, and other molecules.
C. there are two mechanisms to transport molecules and ions through the cell, these are called: the Carrier mediated transport and the Non-carrier mediated transport.
D. the carrier mediate transport is the diffusion and osmosis
E. all of the above

Answer 1

D

Question 2

the passive transport is the net movement ………………….. a concentration gradient.
and it ………… require energy (ATP)

Answer 2

down

Doesn’t

Question 3

the active transport is the net movement ……………….. a concentration gradient
and it mainly …………….. ATP

Answer 3

Against

require

Question 4

what is the difference between primary and secondary active transport?

Answer 4

the primary active transport is the transport of molecules against a concentration gradient by the use of energy from ATP

while the secondary active transport is the transport of two different molecules across the membrane using energy in other forms than ATP. in this type, the ions serve as driving molecules while other molecules serve as driven molecules
for ex: The glucose sodium pump. Is able to pump glucose out against its concentration gradient by bringing sodium back into the cell towards its concentration gradient.

Question 5

state the type of transport for the following structural feature:

1. Passage through channels and pores:
2. Transporter mediated passage:
3. Vesicular transport:

Answer 5

1. passive transport
2. passive and active (1’ and 2’) transport
3. active transport

Question 6

which of the following is wrong about diffusion?

A. Diffusion occur unidirectionally.
B. Since molecules are in constant movement, limited diffusion occurs also from low to high concentration.
C. The difference between diffusions to two different directions determines the net result.
D. Net diffusion occurs through a concentration gradient from high to low concentration
E. Net diffusion occurs through a concentration gradient from high to low concentration

Answer 6

A
Diffusion does not occur unidirectionally.
which means that diffusion is bidirectional

Question 7

the diffusion rate depend on all the following except:

A. Concentration difference
B. temperature
C. shape of the substance
D. weight of the molecules
E. membrane surface area and permeability

Answer 7

C

Question 8

choose the correct statement about diffusion through membranes:

A. It’s Slower than diffusion in water.
B. The main limiting factor is the lipid bilayer.
C. Polar or ionized molecules almost never diffuse.
D. Solubility in lipids help diffusion through membrane
E. all of the above

Answer 8

E

Question 9

true or false:

Free diffusion of gases through capillary wall and the alveolar membranes.

Answer 9

true

Question 10

which of the following is correct about electrochemical gradient?

A. Ion transport through the membranes does not depend only on concentration gradient.
B. Due to resting electrical potential of the plasma membrane, positive ions are attracted to inside while negative ions are repelled.
C. The balance between the concentration gradient and electrical forces determines the direction of transport of the ion.
D. all of the above
E. all except B and D

Answer 10

D

Question 11

state the different types of gates?

Answer 11

1. Ligand gated
2. Voltage gated
3. Secondary messanger gated
   (including Ca++)
4. Temperature gated
5. Mechanically gated
6. ph gated

Question 12

choose the correct statement about facilitated diffusion
(( you can choose more than one answer ))..

A. A carrier protein transfers molecules by conformational change.
B. The net flux occurs according to the concentration gradient.
C. facilitated diffusion requires energy.
D. The best example is glucose transport: GLUTs (14 members in 3 classes)

Answer 12

A, B, D

Question 13

which of the following is wrong regarding the factors determining the rate of facilitated diffusion

A. Affinity of the carrier to the substance.
B. size of carrier proteins in the membrane
C. The rate by which carrier changes its conformation.
D. all of the above

Answer 13

B

Number of carrier proteins in the membrane

Question 14

which of the following is correct about osmotic pressure

A. The pressure needed to prevent water diffusion to a solution. B. The higher the osmolarity the higher the osmotic pressure.
C. The osmolarity of body fluids is about 300 mOsm/l.
D. The osmolarity of extracellular fluids is determined mainly by Na+ and Cl-. For intracelluar fluids this is K+.
E. all of the above

Answer 14

E

Question 15

One mol NaCl ionize to Na+ Cl- to create a ……….. osmolar solution.
•One mol glucose create ………….. osmolar solution.

Answer 15

2

1

Question 16

water molecules can also be transported through narrow pores called …………………………….

Answer 16

aquaporin channels

Question 17

true or false

There are 40 different subtypes of aquaporin channels distributed in different organs and tissues.

Answer 17

false

they are 10

Question 18

what is the difference between connexons and pannexons?

Answer 18

connexons are also called gab junction proteins, re structurally related transmembrane proteins that assemble to form vertebrate gap junctions.

pannexons are hemichannels that have different structure from the connexons and they are mainly the same but with different function. pannexons also contain a glycerol.

Question 19

what is active transport?

Answer 19

Transport of substances against a concentration gradient by special pumps.
It requires energy

Question 20

which of the following is correct about Na - K ATPase?

A. 3 Na+ out, 2 K+ in.
B. 70% of ATP consumption in the brain.
C. It also produces heat: contributes to the thermogenesis.
D. all of the above

Answer 20

D

Question 21

which of the following about secondary active transport is wrong

A. Ion gradient is used for energy not ATP.
B. Beside the main carried substance, there is also a site on the carrier protein to bind the ion.
C. This ion is usually K+.
D. all of the above

Answer 21

its C

This ion is usually Na+.

Question 22

………………………………. the substance is carried in the same direction with Na+.

……………………………….. the subtance is carried in the opposite direction with Na+.

Answer 22

symport

antiport

Question 23

Ca++ transport is what type of secondary transport?

Answer 23

its antiport

Question 24

vesicular transport have 2 types what are they?

Answer 24

endocytosis and exocytosis

Question 25

which of the following is a type of endocytosis:

A. Receptor mediated endocytosis, clathrin system
B. Caveola mediated endocytosis: may be receptor mediated
C. Pinocytosis
D. Phagocytosis
E. all of the following

Answer 25

E

Question 26

the term “cell drinking” means …………………….

and the term “cell eating” means ……………………….

Answer 26

pinocytosis

phagocytosis

Question 27

Endocytotic vesicles have two fates, what are they?

Answer 27

1. The may traverse the cell and leave the cell by exocytosis:
   transcytosis
2. They fuse with lysosomes and particles are digested: endosome system

Question 28

in exocytosis, there are 3 main pathway:

Answer 28

Constitutive secretory pathway
Regulated secretory pathway
Lysosomal secretory pathway

Question 29

which secretory pathway delivers lipids and proteins to the cell membrane?

Answer 29

The constitutive secretory pathway

Question 30

which secretory pathway delivers hormones and neurotransmitters?

Answer 30

regulated secretory pathway

Question 31

which secretory pathway delivers cargo to the membrane or digest and eject debris out of the cell?

Answer 31

lysosomal secretory pathway

Question 32

which of the following is correct regarding exosome and ectosome

I . Special vesicles released by exocytosis or membrane budding.
ii . They carry various cargos like proteins and nucleic acids (RNA and DNA).
iii . They are thought to signal and modify behaviour of other cells.
iv . Important to develop new therapies and understand pathogenesis of diseases.
v. they are multivasicular bodies

Answer 32

all except v

cuz only exosomes are multivasicular

Question 33

in resting membrane potential, Inside of the membrane is more ………………………… relative to outside.

Answer 33

negative

Question 34

which of the following is correct about equilibrium potential for Na+?

A. Assume artificial cell with membrane permeable to Na+ but to nothing else
B. Redistribution of Na+ until movement
down concentration gradient is exactly opposed by movement down electrical gradient.
C. Na+ enters the cell until the + charge inside becomes big enough to repel and doesn’t let in any more Na+.
D. Equilibrium potential for Na+ = + 60 mV
E. all of the above

Answer 34

E

Question 35

Resting Membrane Potential of most cells is between …………… and …………….

Answer 35

50 and 90

Question 36

which equation calculate the equilibrium potential of an ion?

Answer 36

Nernst equation

Veq = RT/ zF ln [ X out / X in ]

Question 37

what is Goldman - Hodgkin - Katz equation?

Answer 37

search it on google :)

Question 38

which of the following is correct about action potential?

I. A sudden, fast, transitory, and propagating change of the resting membrane potential.

ii. Only neurons and muscle cells are capable of generating an action potential; that property is called the excitability.
iii. It is an efficient way to transmit electrical signals without attenuation.
iv. all of the above

Answer 38

iv

Question 39

the “proliferation” is associated with which cell type?

Answer 39

vascular smooth muscle cells
stem cells
cancer cells