Level 2 Biology: Osmosis Internal Flashcards
What does ‘hydrophobic’ mean?
water “hating”
What does ‘hydrophilic’ mean?
water “loving”
What is a phospholipid composed of?
Phosphate group and lipid
What is a ‘Bi-layer’
2 layers
What is a ‘Semi permeable membrane’?
It will only allow certain substances into and out of the cell
What can a phospholipid bilayer act as a barrier between?
A phospholipid bilayer can act as a barrier between two aqueous environments.
passive transport
Does not require energy. Movement of molecules across the cell membrane
Active transport
Requires energy (ATP)
Dependent on the permeability of the cell membrane there are 3 main kinds of passive transport. What are they?
1) Diffusion
2) Osmosis
3) Facilitated diffusion
Definition of Diffusion
Diffusion is the movement of molecules from an area of high concentration to one of low concentration. It uses no energy.
What are the 3 key points on ‘Concentration gradient’
1) For things to diffuse there must be a difference in concentration between two areas.
2) If not, the particles won’t be able to move to a lower concentration.
3) The bigger the difference in concentration the faster it will diffuse.
What does the ‘rate of diffusion’ depend on? (4 things)
1) The concentration gradient (bigger difference, the faster the diffusion).
2) Temperature (warmer=faster diffusion)
3) Particle size (Smaller=faster)
4) State of matter (gas=Faster diffusion)
What is ‘Facilitated diffusion’
Substances are helped across the membrane by carrier proteins. It still uses no energy but the proteins are specific to certain molecules.
How do cells absorb glucose?
Cells absorb glucose by facilitated diffusion. Insulin activates the transport proteins, if insulin is not there- can’t absorb glucose
What is the cell membrane impermeable to?
Most electrically charged molecules and large water soluble substances such as glucose and amino acids.