Module 1: Lecture 6

Question 1

what is diffusion?

Answer 1

the movement of molecules from one area to another area. move from more concentrated to less concentrated but also from less concentrated to more concentrated just not as frequently

Question 2

what does steady state equilibrium mean?

Answer 2

no net change. there is still movement just no NET movement

Question 3

what is electrical gradient?

Answer 3

difference in charge of molecules on one side vs the other

Question 4

what is passive diffusion? give an example

Answer 4

concentration or electrical gradient is moving it. naturally moving without an outside energy force. moves from high concentration to low concentration.
- example: oxygen transport across lung membrane

Question 5

in regards to the cell, is oxygen concentration going to be higher inside or outside of the cell? why?

Answer 5

outside. because it gets converted into water once it enters the cell.

Question 6

what is Fick’s law of diffusion?

Answer 6

the collective influence of factors on the rate of net diffusion of a substance across a membrane
- essentially: the sum of the factors that influence the rate of diffusion will tell you how fast something will diffuse across the plasma membrane

Question 7

does greater molecular weight of substance increase or decrease effect on rate of net diffusion? (MW)

Answer 7

decrease (makes it move slower)

Question 8

does greater surface area of membrane increase or decrease effect on rate of net diffusion? (A)

Answer 8

increase (makes it faster)

Question 9

does greater concentration gradient of substance increase or decrease effect on rate of net diffusion? (Delta C)

Answer 9

increase (makes it faster)

Question 10

does increased distance (thickness of plasma membrane) increase or decrease effect on rate of net diffusion? (delta X)

Answer 10

decrease (makes it slower)

Question 11

an example of a cell we would want to have a very thin plasma membrane?

Answer 11

red blood cells so oxygen can travel as fast as possible

Question 12

does higher lipid solubility increase or decrease effect on rate of net diffusion? (beta)

Answer 12

increase (makes it faster)

Question 13

the passive diffusion of ions is affected by?

Answer 13

concentration gradients (chemical) and the electrical charge both at the same time

Question 14

what is a positively charged ion called?

Answer 14

cation

Question 15

what is a negatively charged ion called?

Answer 15

anion

Question 16

the combinatorial effect of the concentration and electrical gradients on the ion forms the?

Answer 16

electrochemical gradient

Question 17

what are the two ways that water can permeate the plasma membrane?

Answer 17

1. can slip between the phospholipid molecules
2. through specific water channels called Aquaporins (up to one BILLION molecules/second)

Question 18

the diffusion of water molecules is called what?

Answer 18

osmosis

Question 18

what is the driving force of osmosis?

Answer 18

concentration gradient

Question 19

what is hydrostatic (fluid) pressure?

Answer 19

the pressure exerted by a standing, or stationary, fluid on an object
(ex. when too much water is on one side, it puts opposing pressure on the osmosis to stop it from sending more water)

Question 20

what is the osmotic pressure of a solution?

Answer 20

a measure of the tendency for water to move into that solution because of the concentration of non-penetrating solutes and water

Question 21

when there is a impermeable to solute membrane, when can equilibrium happen?

Answer 21

when osmotic pressure and hydrostatic pressure are equal because the net movement will be zero