transport across membranes

Question 1

factors that affect the rate of transport across a membrane ?

Answer 1

• temperature (kinetic energy)
• surface area (larger area = more transport)
• volume or distance (bigger volume = bigger distance so it takes longer for particles to move across the membrane )
• concentration gradient

Question 2

Fick’s law equation

Answer 2

rate of transport is directly proportional to size of surface area x distance in conc / transport distance or volume

Question 3

what is the rate of diffusion if there is a shallow conc gradient, a large distance and the temp is 10 degrees ?

Answer 3

a slow rate of diffusion

Question 4

what is the rate of diffusion if there is a steap conc gradient, small distance and the temp is 20 degrees ?

Answer 4

fast rate of diffusion

Question 5

where does simple diffusion occur ?

Answer 5

through the phospholipid bilayer

Question 6

what

Question 7

is the definition of simple diffusion ?

Answer 7

the net movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached
this process does not require atp

Question 8

hat kind of substances does simple diffusion only involve ?

Answer 8

small, lipid soluble substances

Question 9

what happens to water soluble substances such as Na + in simple diffusion ?

Answer 9

the phospholipid bilayer acts as a barrier and bounces off Na+

Question 10

what is used to transport water soluble molecules in facilitated diffusion ?

Answer 10

intrinsic proteins are used o transport molecules and allow their passage

Question 11

what are the 2 types of facilitated diffusion ?

Answer 11

facilitated diffusion involving channel proteins

facilitated diffusion involving carrier proteins

Question 12

hat do protein channels form ?

Answer 12

they form tubes filled with water which enable water soluble ions to pass through the membrane

Question 13

at are channel proteins regarding the selectivity ?

Answer 13

channel proteins are specific

Question 14

what do carrier proteins involve ?

Answer 14

a shape change

Question 15

what do carrier proteins do ?

Answer 15

carrier proteins bind with a molecule which causes a change in the shape of a protein the shape change enables the molecule to be released to the other side of the membrane

Question 16

what is meant by active transport ?

Answer 16

the movement of molecules and ions from an area of lower conc to an area of higher conc against a concentration gradient using ATP and carrier proteins

Question 17

what do the carrier proteins act as in active transport ?

Answer 17

they act as pumps to move substances across the membrane

Question 18

what is active transport in terms of selectivity ?

Answer 18

it is very selective as only certain molecules can bind to the carrier proteins to be pumped
only those that are complement5ary tp the protein

Question 19

what kind of molecules can be transported in active transport ?

Answer 19

any substances
they dont have to be lipid or water soluble