Watch the animation, then state the process being shown
What process was shown?
What is diffusion?
The movement of substances down a
concentration gradient from a region of high
concentration to a low concentration
Describe what happened in the animation
Watch the next animation and
state what process is shown
Extracellular space
Water molecules
Cell membrane
Intracellular space
Extracellular space
Intracellular space
Extracellular space
Intracellular space
Extracellular space
Intracellular space
Extracellular space
Intracellular space
Extracellular space
Intracellular space
Extracellular space
Intracellular space
Extracellular space
Intracellular space
Extracellular space
Intracellular space
Extracellular space
Intracellular space
What process was shown?
Describe what happened in the animation
Why did the water molecule use a channel protein and not
just cross straight through the lipid bilayer?
What is osmosis?
The diffusion of water across a selectively
permeable membrane from a high
concentration to a low concentration
Why does diffusion/osmosis occur?
• Organisms must maintain homeostasis and
diffusion/osmosis allows cells to receive
necessary nutrients and release unwanted
waste
What is needed in mammalian cells?
Ham's Tissue Culture Medium for Mammalian Cells
(amounts dissolved in 1 liter of triple distilled water)
L-Arginine
211 mg
Biotin
0.024 mg
L-Histidine
21 mg
Calcium pantothenate
0.7 mg
L-Lysine
29.3 mg
Choline chloride
0.69 mg
L-Methionine
4.48 mg
i-inositol
0.54 mg
L-Phenylalanine
4.96 mg
Niacinamide
0.6 mg
L-Tryptophan
0.6 mg
Pyridoxine hydrochloride
0.2 mg
L-Tyrosine
1.81 mg
Riboflavin
0.37 mg
L-Alanine
8.91 mg
Thymidine
0.7 mg
Glycine
7.51 mg
Cyanocobalamin
1.3 mg
L-Serine
10.5 mg
Sodium pyruvate
110 mg
L-Threonine
3.57 mg
Lipoic acid
0.2 mg
L-Aspartic acid
13.3 mg
CaCl2
44 mg
L-Glutamic acid
14.7 mg
MgSO4.7H2O
153 mg
L-Asparagine
15 mg
Glucose
1.1 g
L-Glutamine
146.2 mg
NaCl
7.4 g
L-Isoleucine
2.6 mg
KCl
285 mg
L-Leucine
13.1 mg
Na2HPO4
290 mg
L-Proline
11.5 mg
KH2PO4
83 mg
L-Valine
3.5 mg
Phenol red
1.2 mg
L-Cysteine
31.5 mg
FeSO4
0.83 mg
Thiamine hydrochloride
1 mg
CuSO4.5H2O
0.0025 mg
Hypoxanthine
4 mg
ZnSO4.7H2O
0.028 mg
Folic acid
1.3 mg
NaHCO3
1.2 g
Why are so many nutrients needed
for mammalian cells?
• Because mammals have several different
cells that perform different tasks and would
require different nutrients to perform those
tasks
Cellular Transport in other
organisms
How osmosis works
Osmosis in an Elodea Leaf
• Elodea is a common freshwater plant that is
frequently used to decorate aquariums.
• Freshwater is hypotonic to Elodea and maintains
normal osmotic pressure (internal pressure) in
the plant.
• A hypotonic solution is a solution that contains
less (hypo) solutes than the cytoplasm of the
cell.
• Thus, a hypotonic solution has more water than
the cell and water has a tendency to move
(diffuse) into the cell.
• Plant cells do not rupture because the cell walls
resist the outward expansion of the plasma
membrane.
What happens to Elodea in a hypotonic
solution?
Osmotic pressure increases because
water enters the cell
Osmosis in an Elodea Leaf
• A hypertonic solution is a solution that
contains more (hyper) solutes than the
cytoplasm of the cell.
• Thus, a hypertonic solution has less water
than the cell and water has a tendency to
move (diffuse) out of the cell.
• Plant cells do not shrivel because the cell
walls resist the inward decrease of the
plasma membrane.
What happens to Elodea in a hypertonic
solution?
Osmotic pressure decreases because
water leaves the cell
• Water will continue to move mostly into or
out of a cell until it has reached equilibrium
• Once the cell has reached equilibrium or
homeostasis, water continues to move in
both direction
Osmosis in human blood cells
What happens to a red blood cell in an
Isotonic solution?
It means you have an
equal amount of
solute inside and
outside the cell
10% salt
10% salt
Red blood cells
Plant cell
What happens to a red blood cell in a
Hypotonic solution?
Because there is
only a cell
membrane the
blood cell could
burst
10% salt
20% salt
Red blood cells
Plant cell
What happens to a red blood cell in a
Hypertonic solution?
Red blood cells
will shrivel up
because the cell
membrane does
not provide
enough support
20% salt
10% salt
Red blood cells
Plant cell
Osmosis in Paramecium
Paramecia are freshwater protozoa (singlecelled eukaryotes) found in pond water
• Freshwater is hypotonic to Paramecium,
and results in the osmotic movement of
water into the cell.
• Specialized organelles called contractile
vacuoles function in the homeostatic
maintenance of normal osmotic pressure
Paramecium
Contractile vacuoles
Paramecium
Types of Diffusion
Passive diffusion and Active diffusion
Facilitated Diffusion a form of Passive
Diffusion
• Movement of molecules such as glucose and water
through the cell membrane using channel and carrier
proteins
• Does not require the input of energy
• Example: osmosis
Active Transport
• Movement of material from low
concentration to high concentration or
against the concentration gradient
• Requires energy
concentration gradient
high
high
low
low
With the concentration gradient Is energy input needed?
Against the concentration gradient Is energy input needed?
Movement of nutrients and waste
across the cell membrane
Endocytosis/phagocytosis
• A type of active transport
that moves large
amounts of material into
the cell
• Endo= into Cyto= cell
Exocytosis
• Another type of active
transport removes large
amounts of materials out
of the cell
• Exo= out of Cyto= cell