Passive, Facilitated and Active Transport

Question 1

what is passive transport

Answer 1

movement of biochemicals and molecules across membranes that does not require energy

Question 2

what does the initial rate of passive transport depend on

Answer 2

the concentration differential across the membrane and the permeability of the cell membrane

Question 3

what is facilitated diffusion

Answer 3

a type of transport where molecules or ions cross a membrane via transmembrane integral proteins

Question 4

what is active transport

Answer 4

movement of molecules across membranes that use energy

Question 5

what is osmosis

Answer 5

spontaneous movement of solvent molecules through a semi-permeable membrane into a region of higher solute concentration to equalize solute concentrations

Question 6

what is osmotic pressure

Answer 6

the pressure required to maintain equilibrium with no net movement of solvent

Question 7

what molecules can most easily cross a membrane to most difficult

Answer 7

hydrophobic molecules, small uncharged polar molecules, large uncharged polar molecules

Question 8

what is a channel

Answer 8

a family of biological membrane proteins which allow the passive movement of ions, water, or other solutes to passively pass through the membrane down their electrochemical gradient

Question 9

what is a transporter

Answer 9

membrane protein involved in the movement of ions, small molecules, or macromolecules

Question 10

what type of proteins are transporters

Answer 10

integral membrane proteisn

Question 11

what type of transport do transporters use

Answer 11

either facilitated diffusion or active transport

Question 12

what is another term for transporting across a membrane done by a transporter protein

Answer 12

carrier mediated transport

Question 13

Explain the function of Na-K ATPase and how it works

Answer 13

helps maintain the resting potential and regulate cellular volume. it transports 2K+ ions in for every 3 Na+ ions pumped out using ATP

Question 14

how much energy is the Na+ K+ ATPase responsible for in cell’s energy? neurons?

Answer 14

cells: 1/5
neurons: 2/3

Question 15

describe the relationship between rate of transport and concentration of transported molecules in simple diffusion

Answer 15

it is linear. rate of transport is proportional to concentration of molecules

Question 16

describe the relationship between rate of transport and concentration of transported molecules in transporter mediated

Answer 16

exponential. the rate of transport reaches a maximum when transport protein is saturated

Question 17

what are the 3 ways to drive active transport

Answer 17

coupled, ATP-driven, and light driven pumps

Question 18

how does coupled transport work

Answer 18

transport of one molecule against a concentration gradient is coupled to another molecule being transported down its concentration gradient

Question 19

how does ATP-driven active transport work

Answer 19

invovles energy derived from ATP hydrolysis to move a molecule against its concentration gradient

Question 20

what are light-driven pumps in active transport

Answer 20

uses energy from light in bacteria

Question 21

what is uniport

Answer 21

simple diffusion where one molecule crosses a membrane through a transport protein

Question 22

what is symport

Answer 22

2 molecules cross the membrane using a transporter

Question 23

what is antiport

Answer 23

one molecule goes from the inside of the membrane to the outside and another molecule travels the opposite direction through a transporter

Question 24

explain how the glucose carrier works

Answer 24

the binding of Na+ and glucose are cooperative. when one binds, the other binds. when both are bound it induces a conformational change in the protein that results in the release of glucose and Na+ into the cytosol

Question 25

why is the sodium potassium pumps always active

Answer 25

because cells are leaky

Question 26

what are cell junctions

Answer 26

cell to cell and cell to matrix interactions mediated by extracellular proteins that hold cells together to form tissues

Question 27

what are the 4 major classes of cell junctions

Answer 27

anchoring junctions, occluding junctions, channel forming junctions (communicating) and signal relaying junctions

Question 28

what are the types of junctions in occluding junctions and where are they found

Answer 28

1. tight junctions (vertebrates)

2. septate junctions (invertebrates)

Question 29

what are the 2 types of anchoring junctions and what 2 locations are they found in

Answer 29

cell to cell junctions and cell to matrix junctions found in actin filament attachment sites and intermediate filament attachment sites

Question 30

what are the cell to cell junctions in actin filament attachment sites and intermediate filament attachment sites known as

Answer 30

actin: adherens junctions

intermediate filament: desmosomes

Question 31

what are the cell to matrix junctions in actin filament attachment sites and intermediate filament attachment sites known as

Answer 31

actin: focal adhesions

intermediate filaments: hemidesmosomes

Question 32

what are the types of junctions in communicating junctions

Answer 32

gap junctions and plasmodesmata (plants only)

Question 33

what is the type of junction in signal relaying junctions called

Answer 33

chemical synapses

Question 34

what are adherens junctions

Answer 34

new cells remain in tissue and are anchored to basal lamina and each other by adherens junctions

Question 35

what is the role of cadherins in adherins junctions

Answer 35

adherins junctions require ca2+ for cadherin binding. it needs cadherin to bind the cells together

Question 36

explain how connexins and gap junctions work together

Answer 36

gap junctions are protein “tubes” made of connexin monomers which connect two cells by penetrating the cell membranes of two adjacent cells. it provides a fluid space through which materials can pass from one cytoplasm to the next