Module 1: Lecture 7

Question 1

what is tonicity?

Answer 1

the effect the solution has on cell volume

Question 2

the tonicity of the solution is determined by?

Answer 2

the concentration of the solution in nonpenetrating solutes (the penetrating ones are rapidly equally distributed between extracellular fluid and intercellular fluid)

Question 3

what is the solute called when it is impermeable to the membrane?

Answer 3

nonpenetrating solute

Question 4

what is the only thing that will affect cell VOLUME?

Answer 4

nonpenetrating solute (tonicity)

Question 5

a cell has a higher WATER concentration than outside the cell, is the cell going to shrink or swell?

Answer 5

shrink (hypertonic)

Question 6

what are the three tonicities?

Answer 6

1. isotonic: constant cell volume
2. hypotonic(LOWER NONPENETRATING solute concentration outside the cell): swell the cell
3. hypertonic(HIGHER NONPENETRATING solute concentration outside the cell): shrink the cell

Question 7

what is osmolarity?

Answer 7

the measure of solute concentration per unit volume of solvent
- takes into account ALL solute concentrations (penetrating AND nonpenetrating solutes)

Question 8

what are the three types of osmolarity?

Answer 8

1. iso-osmotic
2. hypo-osmotic
3. hyper-osmotic

Question 9

if a cells volume is 300mL, and the nonpentrating solution is 200mL, and the pentrating solution is 400mL, what is the tonicity and osmolarity of the solution?

Answer 9

tonicity: hypertonic
osmolarity: hyper-osmotic

Question 10

when trying to find tonicity, what are you counting?

Answer 10

ONLY NON-penetrating solutes

Question 11

what is the pressure forced by the movement of water called?

Answer 11

osmotic pressure

Question 12

what type of nonpenetrating solutes has the biggest impact on cell volume?

Answer 12

ions

Question 13

what happens to an ionic compound and its osmolarity once you drop it in a solution?

Answer 13

it will dissociate into two ions and each will have its own osmolarity

Question 14

in what case will osmolarity be more or larger than molarity?

Answer 14

when its an ionic compound

Question 15

when an ionic compound is broken down, what is the osmolarity increased to?

Answer 15

if it dissociates into two compounds, osmolarity is double molarity. if it dissociates into three compounds, osmolarity is triple molarity.
etc, etc.

Question 16

when trying to find the tonicity of an ionic compound solution, the outside solution used is what?

Answer 16

the sum of molarity of all compounds involved

Question 17

what are the two different mechanisms for assisted membrane transport?

Answer 17

1. carrier-mediated transport (for small water-soluble molecules)
2. vesicular transport (larger molecules)

Question 18

what is vesicular transport?

Answer 18

engulfing the molecule transporting in a vesicle

Question 19

what is carrier-mediated transport?

Answer 19

assist molecules passively through the plasma membrane

Question 20

what are the three important characteristics of carrier-mediated transporter?

Answer 20

1. specificity (amino acids cannot bind to glucose carriers)
2. saturation (limited by number of carrier binding sites (how many and how much they can hold))
3. competition (closely related molecules can compete for the some transporter)

Question 21

difference between diffusion and facilitated diffusion?

Answer 21

facilitated needs a carrier molecule

Question 22

facilitated diffusion uses what type of transport?

Answer 22

passive transport (does not require energy)
- down the concentration gradient

Question 23

glucose uses what type of membrane transportation to get across the plasma membrane?

Answer 23

facilitated diffusion

Question 24

does saturation (limited binding/transportation) occur in simple diffusion?

Answer 24

no, only facilitated diffusion because it needs carriers