Transcript Passive Transport

Passive Transport
• Passive transport: Cell spends no energy (ATP) to move
molecules
Does this kayaker need
to spend his energy in
order to move?
Passive Transport
• Passive transport: Cell expends no energy (ATP) to move
the molecules
• Molecules move from a high to low concentration
– Down their concentration gradient
• Examples:
o Diffusion
o Osmosis
o Facilitated diffusion
• Diffusion: Movement of molecules from an area of high to
low concentration
• Movement continues until equilibrium is reached
– Equilibrium: even balance of molecules
• This is how many molecules move into and out of cells
O2
O2
O2
O2
O2
O2
O2
O2
O2
O2
Will oxygen mostly
enter or exit this cell?
O2
O2
O2
O2
O2
O2
O2
O2
O2
O2
O2
O2
• Diffusion: Movement of molecules from an area of high to
low concentration
• Movement continues until equilibrium is reached
– Equilibrium: even balance of molecules
• This is how many molecules move into and out of cells
Diffusion Video Clip
The woman inhales a breath of oxygen
The
oxygen
spreads
into the
womans
lungs
The oxygen fills
the air sacs
(alveoli) located
in her lungs
Where is the HIGH
oxygen
concentration?
Where is the LOW
oxygen
concentration?
Due to
diffusion,
the oxygen
will spread
from her
lungs… into
her blood
The heart pumps this
oxygen-rich blood
around her body
Cell X needs oxygen just like all cells. But cell X is not in direct
contact with the blood and oxygen. So how does cell X get oxygen?
Diffusion: movement of molecules from a high to low concentration
Where is the HIGH oxygen concentration?
Where is the LOW oxygen concentration?
Cell X (and all other cells) gets oxygen through the process of
diffusion!
The reverse process is true w/ carbon dioxide. Over time, CO2
waste builds up in cells. Too much is fatal. It must be removed.
Where is the HIGH carbon dioxide concentration?
Where is the LOW carbon dioxide concentration?
CO2 diffuses from the cells (high concentration) and into the
blood stream (low concentration)
The heart pumps the CO2 rich blood back to the lungs.
Where is the HIGH
carbon dioxide
concentration?
CO2 diffuses into
the air sacs
(alveoli)
The woman begins
to exhale
The
diaphragm
muscle
pushes the
CO2 out of
the lungs
CO2 is expelled… the process repeats with every breath!
Osmosis
• Defined: Diffusion of
water from a high to
low concentration
• High H2O
concentration
– Less solutes
(hypotonic solution)
– Ex: Distilled water
Distilled water
(no solutes in water)
Cell
(High solutes)
Cell
Osmosis
• Defined: Diffusion of
water from a high to low
concentration
• High H2O
concentration
– Less solutes
(hypotonic solution)
– Ex: Distilled water
• Low H2O concentration
– More solutes
(hypertonic solution)
– Ex: Salt water
Salt water
(high solutes)
Cell
(low solutes)
Cell
Isotonic- when the concentration of
solutes is the same inside and outside
the cell.
Many cells contain water channel
proteins called aquaporins
Facilitated Diffusion
glucose
Protein
channel
• Facilitate means “to help”
glucose
• Defined: Larger molecules enter/exit with the help
of protein channels in the plasma membrane
• No energy (ATP) used
Facilitated Diffusion
Review
1) In which direction does diffusion occur?
2) Across which part of the cell does diffusion mostly
occur?
3) Which molecule of energy is not required during
passive transport?
4) True or False: More solutes creates less concentrated
water.
5) Which chemical is involved in osmosis?
6) Examine the picture. If the dots are solutes, where is
the high solute concentration?
7) Examine the picture. If the dots are water molecules,
where is the low water concentration?
8) Examine the picture. If the dots are water molecules,
which way will osmosis occur?
9) Examine the picture. If the dots are solute molecules,
which way will osmosis occur?
Review
10) Place the steps of oxygen flow in the correct order from start to finish.
A – Oxygen diffuses into your cells
B – Your heart pumps oxygen-rich blood around your body
C – Oxygen moves into your lungs
D – Oxygen gas is inhaled
E – Oxygen diffuses from your lungs into your blood
11) Place the steps of CO2 flow in the correct order from start to finish.
A – Your heart pumps CO2-rich blood towards your lungs
B – CO2 waste is created by every cell
C – CO2 is pushed out of your lungs and out of your mouth
D – CO2 diffuses from your blood into your lungs
E – CO2 diffuses from your cells into your blood