Block 1 - Cell Membrane

Question 1

What component of the plasma membrane generates it’s unique nature?

Answer 1

Proteins

Question 2

What can change the shape of a surface protein?

Answer 2

Charge distribution, covalent bonds (i.e. phosphorylation on the ends), allosteric bonds

Question 3

What’s the simplest way for a substance to move through a membrane?

Answer 3

Channel or pore

Question 4

T/F. Size, charge, number, concentration, diffusion rates all play rolls in the semipermeable nature of a plasma membrane.

Answer 4

TRUE

Question 5

T/F Temperature, size of the particle, and the steepness of concentration gradient all play a roll in the speed at which a substance diffuses

Answer 5

TRUE

Question 6

Because molecules are always in motion, they do not only travel in one direction during diffusion. What are the factors involved in Fick’s Law?

Answer 6

Net Flux = P x Area (Conc. in - Conc. out)

Question 7

Where solutes go, ____ is sure to follow

Answer 7

Water

Question 8

What moves to balance concentrations when a membrane is FIXED?

Answer 8

Solute moves

Question 9

What moves to balance concentrations when a membrane is MOVEABLE?

Answer 9

Water moves

Question 10

What’s a simple alternative to a channel where a solute either in the ECF or ICF binds to a site on a protein causing its shape to change and open?

Answer 10

Transporter

Question 11

What is the driving force behind facilitated diffusion?

Answer 11

Concentration gradient and the presence of triggering solutes

Question 12

What is the effect on net flux when it is mediated by a transporter protein?

Answer 12

Eventually you will hit max flux into the cell

Question 13

What two versions of channels or pores exist?

Answer 13

Open channels (pore or leak channels) and ligand binding or voltage gated channels (Na+)

Question 14

What two versions of transporters exist?

Answer 14

Facilitated diffusion proteins and active transport proteins

Question 15

T/F Though simple diffusion doen not require energy to work, facilitated diffusion as well as active transport require energy in the form of ATP.

Answer 15

FALSE. Facilitated diffusion DOES NOT require energy as it simply follows the concentration gradient.

Question 16

How many ATP are burned during one cycle of the Na+/K+ pump?

Answer 16

1

Question 17

____ Na+ are pumped ____ while ____ K+ are pumped ____ during one cycle of the Na+/K+ pump?

Answer 17

3 Na+ are pumped OUT while 2 K+ are pumped IN

Question 18

T/F Every cell has Na+ and K+ leak channels

Answer 18

TRUE

Question 19

Normally, Na+ concentration is ____ inside the cell and ____ outside the cell while K+ concentration is ____ inside the cell and ____ outside the cell.

Answer 19

Low, High - High, Low

Question 20

Of Na+, K+, Ca2+, Mg2+, Cl-…which are generally higher OUTSIDE the cell and have the tendency based on concentration gradient to want to diffuse INTO the cell?

Answer 20

Na+, Ca2+, Cl- are higher outside the cell and K+, Mg2+ are higher inside the cell.

Question 21

With cotransport, small molecules such as ____ and ____ can travel ____ their concentration gradient by traveling with another molecule that is traveling DOWN its concentration gradient.

Answer 21

Sugars, Amino Acids, up/against

Question 22

With SYMPORT the molecule going against its gradient is going the ____ direction as the molecule going down its gradient. With ANTIPORT the molecule going against its gradient is going the ____ direction as the molecule going down its gradient

Answer 22

Same, opposite

Question 23

How many H+ removal systems are there? What are they?

Answer 23

2, primary active transport and secondary active transport

Question 24

Why do we need to continually remove H+ from our cells?

Answer 24

To maintain pH

Question 25

Why do we need to continually remove Ca2+

Answer 25

It plays a roll in metabolism and too much would cause the cells metabolism to be too high and it would burn itself out

Question 26

Why is facilitated transport necessary if it is only traveling down a concentration gradient?

Answer 26

Size is the issue. It’s for larger sugars and amino acids

Question 27

What is the main provider of energy for secondary active transport?

Answer 27

Na+ moving down its concentration gradient

Question 28

With primary active transport, what molecules are moving? Where are they moving? Is energy required? What is the source of the energy?

Answer 28

Na+ out while K+ in (Na+/K+ pump), Ca2+ out, H+ out. Yes energy is required. ATP is the source.

Question 29

With ion channels, what molecules are moving? Where are they moving? Is energy required? What is the source of the energy?

Answer 29

Na+ in, K+ out, Cl- in, Ca2+ in. No energy required, simple diffusion is occurring.

Question 30

With secondary active transport, what molecules are moving? Where are they moving? Is energy required? What is the source of the energy?

Answer 30

Na+ in with amino acids in, Na+ in with H+ out, Na+ in with Ca2+ out, HCO3- out with Cl-in. Yes energy is required. The travel of molecules moving down their gradients allows others to move up their gradients

Question 31

What features limit paracellular epithelial pathways?

Answer 31

Tight junctions

Question 32

The Na+/K+ pump is ALWAYS located on the ____ side.

Answer 32

Basolateral

Question 33

How does Na+ travel through the epithelium from the luminal side and into the blood side?

Answer 33

Travels transcellularly using a Na+ channel to get into the epithelium and a Na+/K+ pump to get out and into the blood side

Question 34

Concentration of Na+ on the lumen side is usually ____ compared to the intracellular concentration which is ____ . The intracellular concentration is significantly ____ than the blood side concentration which is usually the ____

Answer 34

High, low, lower, highest of all three compartments.

Question 35

How does a luminal substance travel through the epithelium from the luminal side and into the blood side?

Answer 35

Travels transcellularly using secondary active transport (hitching a ride with Na+) to get into the epithelium then facilitated diffusion to get out and into the blood side

Question 36

Concentration of luminal substance (X) on the lumen side is usually ____ compared to the intracellular concentration which is ____ . The intracellular concentration is generally ____ than the blood side concentration which is usually the ____

Answer 36

Low, high, higher, lower than the intracellular concentration of X

Question 37

How does water move from the luminal side to the blood side?

Answer 37

Aquaporins (transcellular) and through tight junctions between cells.

Question 38

What does pinocytosis mean?

Answer 38

cell drinking

Question 39

Between endocytosis and exocytosis, the plasma membrane is replaced once every ____

Answer 39

Hour