Download •(High- Low) • (Low - High) 3 Types of Passive Transport

PASSIVE TRANSPORT
• cell uses no energy
• molecules move randomly
• Molecules spread out from
an area of high
concentration to an area of
low concentration.
•(High- Low)
ACTIVE TRANSPORT
• cell uses energy
• actively moves molecules to
where they are needed
• Movement from an area of
low concentration to an area
of high concentration
• (Low - High)
3 Types of Passive Transport
1 Prepared by: Mr. Louie B. Dasas STC, QC
1.
DIFFUSION
• Random
movement of particles from an area of high
concentration to an area of low concentration. (High to
Low)
• Diffusion continues until all molecules are evenly spaced
(equilibrium is reached)
Note: molecules will still move around but stay
spread out.
FACTORS AFFECTING RATE OF DIFFUSION
FACTOR
Increase
in
2.
Temperature
Pressure
Density
Concentration
gradient
EFFECT TO RATE OF
DIFFUSION
FASTER
SLOWER
X
X
X
X
OSMOSIS
2 Prepared by: Mr. Louie B. Dasas STC, QC
Diffusion of water through a selectively permeable
membrane
• Water moves from high to low concentrations
•
WATER POTENTIAL
• Term used to describe the movement of water molecules
as it undergoes osmosis.
• Difference between “Force” that pushes the water
molecules and the “Force” exerted by the membrane
More Solute: Lower Water Less Solute: Higher Water
Potential
Potential
3 Prepared by: Mr. Louie B. Dasas STC, QC
Water Potential Gradient – when two solutions of different
water potentials are separated by a semi
permeable membrane.
Higher
Lower
A- Water
Increase in the water
water
water
B – Starch level to achieve water
potential potential solution
balance
OSMOTIC PRESSURE – “force” that moves water molecules
through a semi permeable membrane
TONICITY
• Refers to the strength of solution in relation to osmosis
Type of Solutions
4 Prepared by: Mr. Louie B. Dasas STC, QC
If the concentration of solute (salt)
is equal on both sides, the water
will move back in forth but it won't
have any result on the overall
amount of water on either side.
"ISO" means the same
The word "HYPO" means less, in
this case there are less solute (salt)
molecules outside the cell, since
salt sucks, water will move into the
cell.
5 Prepared by: Mr. Louie B. Dasas STC, QC
The cell will gain water and grow
larger. In plant cells, the central
vacuoles will fill and the plant
becomes stiff and rigid, the cell wall
keeps the plant from bursting.
TURGOR PRESSURE (Turgidity)
In animals, the cells SWELL
because of movement of water into
the cell. As osmosis continues,
osmotic pressure builds up in the
cell causing LYSIS.
6 Prepared by: Mr. Louie B. Dasas STC, QC
The word "HYPER" means more, in
this case there are more solute
(salt) molecules outside the cell,
which causes the water to be
sucked in that direction.
7 Prepared by: Mr. Louie B. Dasas STC, QC
In plant cells, the central vacuole
loses water and the cells shrink,
causing wilting.
PLASMOLYSIS – cell membrane is
pulled away from the cell wall and
the cytosol shrinks
In animal cells, the cells also
shrink.
When RBCs are placed in a
hypertonic solution, cells undergo
the process of CRENATION (Latin
crenatus meaning Wrinkled)
Note: Crenation is specifically used
for RBCs.
How Organisms Deal with Osmotic Pressure
• Bacteria and plants have cell walls that prevent them from
over-expanding. In plants the pressure exerted on the cell
wall is called turgor pressure.
• A protist like Paramecium has contractile vacuoles that
collect water flowing in and pump it out to prevent them
from over-expanding.
• Salt water fish pump salt out of their specialized gills so
they do not dehydrate.
• Animal cells are bathed in blood. Kidneys keep the blood
isotonic by remove excess salt and water.
8 Prepared by: Mr. Louie B. Dasas STC, QC
3.
FACILITATED DIFFUSION
•
Movement of molecules across the cell
membrane with the help of membrane proteins
TWO TYPES OF MEMBRANE TRANSPORT
a.
Channel Proteins – contain tunnels or openings that
serve as the passage of molecules
b.
Carrier Proteins – undergo temporary binding to the
molecule it carries resulting in a conformational change
that moves the molecule through the membrane
PROPERTIES OF FACILITATED DIFFUSION
 Concentration gradient is required (always high to low
concentration)
 Energy is NOT needed.
 Transport proteins are SPECIFIC to the type of
molecules.
 The rate of transport reaches a maximum when all
membrane transport proteins are used up.
 Membrane transport proteins are SENSITIVE TO
INHIBITORS that can cause them not to function
9 Prepared by: Mr. Louie B. Dasas STC, QC
4.
•
•
•
•
a.
ACTIVE TRANSPORT
cell uses energy
actively moves molecules to where they are needed
Movement from an area of low concentration to an area
of high concentration
(Low ◊ High)
Protein Pumps -transport proteins that require
energy to do work
Example: Sodium / Potassium Pumps are important in
nerve responses.
Protein changes shape to move molecules: this
requires energy!
Endocytosis- taking bulky material into a cell
b.
-
-
c.
“cell eating”
Uses energy
Cell membrane in-folds around food particle
forms food vacuole & digests food
This is how white blood cells eat bacteria!
Exocytosis: Forces material out of cell in bulk
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-
membrane surrounding the material fuses with cell
membrane
Cell changes shape – requires energy
EX: Hormones or wastes released from cell
11 Prepared by: Mr. Louie B. Dasas STC, QC
12 Prepared by: Mr. Louie B. Dasas STC, QC