Transport across the cell membrane Flashcards
(44 cards)
Describe the structure of the cell membrane
The cell membrane is composed of a double layer phospholipid molecules with protein molecules embedded within it
what is the fluid mosaic model
The bolster will always remain arranged in this confirguration but the individual phospholipids are able to move
why is the cell membrane described as selectively permeable
This is because it controls the movement of molecules across it depending on their size
state two molecules that are small enough that they can pass directly through the phospholipid membrane
water and oxygen
state a molecules that requires specific transport proteins to facilitate their movement across the cell membrane
Glucose
state two molecules too big to move through the cell membrane which is said to be permeable to them
Starch and Proteins
what is a concentration gradient
Occurs when the concentration of particles is higher in one area than another
When does a concentration gradient occur
When molecules are not evenly distributed
What direction will molecules always travel in
Molecules will always travel from a high concentration to a low concentration
down the concentration gradient
When will the molecules stop moving
They will stop moving when they are evenly distributed and the concentration gradient no longer exists
name the two types of transport
Passive
active
What are the two examples of Passive transport
Diffusion
Osmosis
Does passive transport need energy
No because it occurs down a concentration gradient think a ball rolling down a hill
Describe diffusion
diffusion is the movement of molecules down a concentration gradient from a higher concentration to a lower concentration
What kind of molecules travel through the cell by diffusion
Glucose
Oxygen
Carbon dioxide molecules
Why is diffusion important to cells
It allows them to gain useful substances they require to obtain energy and grow and let’s them get rid of waste products
describe osmosis
The movement of water molecules from a higher water concentration to a lower water concentration through a selectively permeable membrane
does osmosis require energy
no
how to calculate a percentage change
DOOTH
difference over original times hundred
describe the effect of osmosis of animal cells
if water enters an animal cell by osmosis
the cell will swell up and burst
if water leaves an animal cell by osmosis the cell will shrink
decribe the effect of osmosis on a plant cell
of water enters a plant by osmosis it will swell up and become turgid. The plant cell doesn’t burst because there is a cell wall present
if water leaves a plant cell by osmosis the membrane pulls away from the cell wall and becomes plasmolysed
What has happened to a cell if it has become turgid
water has entered the cell through osmosis
what has happened to the cell of it becomes plasmolysed
water has left the cell wall through osmosis
describe active transport
the movement of molecules from a low concentration to a high concentration
against a concentration gradient
