Ch 3, 3 Membrane transport

Question 1

general functions of plasma membrane

Answer 1

1. selectively permeable-only allows certain molecules through
2. controls movement of materials in and out- how much and when?
3. maintains homeostasis- maintaining sable internal conditions in the body

Question 2

passive processes

Answer 2

no cellular energy (ATP) is required

substance moves down concentration gradient

Question 3

passive characteristics

Answer 3

a. its solubility
- lipid soluble(hydrophobic) substances can diffuse through the phospholipid bilayer
- water soluble (hydrophilic) can not, must use channels or carriers
b. its size
- are there channels in the membrane the appropriate size?
- large lipid molecules cannot get through eg. large proteins
c. Presence of suitable carrier proteins in the membrane
- membrane carrier proteins are specific, can only bind to certain molecules

Question 4

filtration

Answer 4

passive process
-movement against a fluid pressure gradient
materials are carried along with the fluid from a area of high fluid pressure to low fluid pressure

Question 5

simple diffusion

Answer 5

passive process

• non polar(hydrophobic) substances diffuse directly through the phospholipid bilayer following a concentration gradient
• kinetic energy of the molecules cause them to move, random movement
  1. higher conc. higher the rate
  2. bigger the molecule, slower the rate
  3. higher the temp, higher the rate

Question 6

facilitated diffusion

Answer 6

passive process, with carriers or channel proteins
certain hydrophilic molecules use specific carrier or channel proteins to pass through the membrane, eg. glucose, amino acids, ions
-this type of diffusion is..
a. specific
b. rate Is determined by number of carriers or channels
c. rate can be regulated
d. substances can only move with a concentration grad. from high to low

Question 7

using carrier proteins

Answer 7

transmembrane integral proteins transport specific polar molecules (sugars and amino acids)
binding of substrate causes shape change in carrier

Question 8

using channel proteins

Answer 8

aqueous channels formed by transmembrane proteins selectively transport ions or water
two types-
a. leakage channel-always open
b. gated channels- controlled by chemical or electrical signals

Question 9

osmosis

Answer 9

passive process

diffusion of water across a selectively permeable membrane

Question 10

two ways water diffuses through plasma membrane

Answer 10

through the lipid bilayer–wiggles between the phospholipids

through protein channels called aquaporins (AQPs)

Question 11

water diffusion

Answer 11

from high concentration to low

Question 12

aqueous diffusion

Answer 12

water concentration depends on solute concentration- the higher the solute conc. the lower the water (solvent) conc.

Question 13

importance of osmosis

Answer 13

when it occurs, water enters or leaves a cell
change in cell volume disrupts cell function
eg, water enters the cell swells

Question 14

Tonicity

Answer 14

comparative terms used to describe relative concentration of solutes in two different aqueous solutions

Question 15

isotonic solutions

Answer 15

2 solutions with the same solute concentration

Question 16

hypertonic

Answer 16

a solution having a greater solute concentration than another solution

Question 17

hypotonic

Answer 17

a solutions with a lower solute concentration than some other solution

Question 18

effects of isotonic on RBC

Answer 18

no change, water moves equally

Question 19

effects of hypertonic on RBC

Answer 19

cell shrinks
water moves out
loses volume
“crenated”

Question 20

effects of hypotonic on RBC

Answer 20

water moves in
cell bursts
“lysed”

Question 21

osmolarity

Answer 21

the measure of the total concentration of all solute particles in a solution

Question 22

active process

Answer 22

requires carrier proteins (solute pumps)
moves solute against a concentration gradient
requires energy output by cell (ATP)

Question 23

primary active

Answer 23

energy comes directly from hydrolysis of ATP
causes shape change in transport protein so that bound solutes (ions) are pumped across
eg. sodium/potassium pump
in all plasma membranes..essential for muscle and nerve function

Question 24

secondary active

Answer 24

depends on ion gradient crated by primary active transport

energy stored in ionic gradients is used indirectly to drive transport of other substances

Question 25

co transport

Answer 25

active process

always transports more than one substance at a time

Question 26

symport system

Answer 26

two substances transported in same directions

Question 27

antiport system

Answer 27

two substances transported in opposite directions

Question 28

vesicular active transport

Answer 28

transport of large particles, macromolecules and fluids across plasma membranes
requires ATP

Question 29

exocytosis

Answer 29

vesicular transport

transport out of cell, large protein, hormones, mucus

Question 30

endocytosis

Answer 30

transport into the cell..3 types

1. phagocytosis; solid materials are engulfed by pseudopods and brought in to interior cell, carried out by some WBC
2. pinocytosis; liquids and solutes brought into cell by infolding of plasma membrane
   - occurs during nutrient absorption in small intestine
3. receptor mediated endocytosis; specific protein receptors in membrane bind to substances
   - uptake of enzymes, hormones and cholesterol

Question 31

transcytosis

Answer 31

transport into, then across then out of the cell