CELL MEMBRANES
& DIFFUSION
MIXTURE
• TWO OR MORE ELEMENTS THAT ARE
PHYSICALLY MIXED TOGETHER
SUSPENSION
• FLUID AND NONDISSOLVED MATERIAL
SOLUTION
• ALL COMPONENTS ARE EVENLY
DISTRIBUTED AND DISSOLVED
SOLUTE
• SUBSTANCE BEING DISSOLVED
SOLVENT
• Substance that dissolves the solute
SOLUTE
• SUBSTANCE BEING DISSOLVED
SOLVENT
• Substance that dissolves the
solute
CONCENTRATION
• AMOUNT OF SOLUTE PER SOLVENT
• Mass / Volume
EVERYTHING
MOVES FROM
HIGH TO
LOW
DIFFUSION
• MOVEMENT FROM HIGH TO LOW
CONCENTRATION
• Concentration Gradient: the differences in
concentration of two mediums
↑ Concentration Gradient = ↑ Diffusion
Osmosis:
the diffusion of water
EQUILIBRIUM
• CONCENTRATION OF SOLUTE IS THE SAME
THROUGHOUT THE SYSTEM
TONICITY
DIFFERENCE IN WATER CONCENTRATION OF TWO
SOLUTIONS SEPARATED BY A PERMEABLE MEMBRANE
HYPERTONIC MORE SOLUTES IN THE AREA
HYPOTONIC LESS SOLUTES IN THE AREA
ISOTONIC
EQUALS AMOUNTS
HYPERTONIC
10% STARCH
= WATER DIFFUSES OUT OF CELL,
CELL SHRINKS
30% STARCH
HYPOTONIC
30% STARCH
= WATER DIFFUSES INTO CELL,
CELL EXPANDS
10% STARCH
ISOTONIC
20% STARCH
= NO NET MOVEMENT
20% STARCH
Nucleolus
Nucleus
Rough E.R.
Cytoskeleton
Lysosome
Smooth E.R.
Mitochondria
Ribosomes
Vacuole
Plasma
Membrane
Cytoplasm
Golgi
Apparatus
The Plasma Membrane of cells are
made up of a PHOSPHOLIPID BILAYER
Hydrophilic Head
“water-loving”
Hydrophobic Tails
“water-fearing”
The Plasma Membrane of cells also have
PROTEINS and CHOLESTEROL
•
•
Help movement across the
membrane; protein channels
Detect materials outside the cell
•
Help keep the membrane
fluid and wavy
___IN___
Nutrients
- sugars (glucose)
- proteins
- fats
Salts
O2
H2 O
___OUT___
Waste
- ammonia
- salts
- CO2
Products
- Proteins
H2O
•
INSIDE
•
Uncharged smaller particles can pass through the
membrane
Charged particles (+/-) or large particles cannot
SALT
+/-
OUTSIDE
LIPIDS
CO2
WASTES
O2
STARCH
Large and/or charged particles must use Transport
Proteins or Protein Channels to pass through the
plasma membrane
Simple Diffusion
vs. Facilitated Diffusion
• Move from HIGH to LOW directly • Move from HIGH to LOW
through the lipid bilayer
through a transport protein
Passive Transport:
diffusion occurs down the Concentration Gradient
Sometimes, transport needs to occur AGAINST the
Concentration Gradient
Example: Glucose
Cells must use ACTIVE
TRANSPORT to go
against the gradient
Active Transport uses
ATP Energy to push
materials from LOW to
HIGH concentration
Facilitated Diffusion
Active Transport
Passive
Transport
Simple Diffusion
shipping out of the cell
shipping into the cell
https://www.youtube.com/watch?v=prfMUwjobo8
How does endocytosis and exocytosis
work?
https://www.youtube.com/watch?v=XdCrZm_JAp0