4.2- DIFFUSION Flashcards Preview

B4- TRANSPORT ACROSS CELL MEMBRANES > 4.2- DIFFUSION > Flashcards

Flashcards in 4.2- DIFFUSION Deck (29)
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1

What is exchange of substances between cells and environment that require metabolic energy called?

active transport

2

What is exchange of substances between cells and environment that don't require metabolic energy called?

passive transport

3

What is diffusion an example of?

passive transport

4

Do all movement involve energy?

yes

5

What does 'passive' mean in passive transport?

energy comes from natural, inbuilt motion of particles, rather than from some external source i.e. ATP

6

How are all particles constantly in motion?

due to K.E. they possess

7

What is the motion of the particles?

random with no set pattern to the way particles move around

8

Where are particles bouncing off of constantly?

bouncing off one another as well as off other objects i.e. sides of vessel in which they're contained

9

What is the definition of diffusion?

net movement of molecules/ions from region where they're more highly concentrated to one where their concentration is lower until evenly distributed

10

Examples of molecules that can diffuse across the cell-surface membrane?

carbon dioxide and oxygen

11

Why do charged ions and polar molecules not diffuse across plasma membranes?

because of phospholipids in membrane

12

How is the movement of charged ions and polar molecules made easier (facilitated)?

by transmembrane channels and carriers that span the membrane

13

What is the process by which movement of charged ions and polar molecules made easier called?

facilitated diffusion

14

Is facilitated diffusion an active or passive process?

passive process

15

What does facilitated diffusion rely on?

inbuilt motion (KE) of diffusing molecules
no external input of ATP from respiration

16

Does facilitated diffusion occur down or against a concentration gradient?

down a concentration gradient

17

How does facilitated diffusion differ from diffusion?

occurs at specific points on plasms membrane where there are special protein molecules

18

What two types of proteins are involved in facilitated diffusion?

protein channels and carrier proteins

19

What do protein channels form?

water-filled hydrophilic channels across the membrane

20

What do protein channels allow?

specific water-soluble ions to pass through

21

Are the channel proteins selective or not?

selective

22

What does it mean for the channel protein to be selective?

each opening in presence of specific ion
if particular ion not present, channel remains closed

23

Why is channel proteins being selective a good thing?

control over entry/exit of ions

24

What do the ions do with the channel protein?

they bind with the channel protein

25

What happens when the ions bind to the channel protein?

causes channel protein to change shape in a way that closes it to one side of membrane + opens it to other side

26

What does an alternative form of facilitated diffusion involve?

carrier proteins that span the plasma membrane

27

What happens when a molecule i.e. glucose that's specific to the carrier protein is present?

it binds with the protein

28

What happens when the molecule binds with the carrier protein?

causes it to change shape in such way that molecule released to inside of membrane

29

Is external energy needed for facilitated diffusion with carrier proteins?

no