Download Passive Transport * movement of molecules without using energy

Cell Transport
Structure of the cell membrane:
Structure of the cell membrane:
1. Phospholipid bilayer – hydrophobic
tails together
2. Channel proteins – allow certain ions
to pass through
3. Carrier proteins – assist larger
molecules across the membrane
4. Marker proteins – have carbohydrate
chain as sensor
Passive Transport – movement of
molecules without using energy
1. Diffusion-molecules move
from high to low concentration
2. Osmosis – diffusion of water
to speed up diffusion – stir, heat,
or increase the concentration
Types of solutions:
Hypotonic- high concentration outside
the cell, water moves into the cell, cell
swells
Hypertonic – high concentration inside
the cell, water moves out, cell shrinks
Isotonic – equal concentration inside and
out side of the cell, no change in size
Which type of solution is each cell in?
Examples:
1. Ameba in a pond
Hypotonic:
- More water outside than
inside, water moves into the cell
- Uses its contractile vacuole to constantly pump
water out of the cell
- Cytolysis – cell bursts from internal pressure
Examples:
2.plant roots in moist soil
Hypotonic:
-water diffuses into the roots
-Central vacuole is full,
pushes against the cell wall
-cell has high turgor pressure
(water pressure inside the plant cell)
Examples:
3.plant roots in dry soil
Hypertonic:
-water diffuses out
-Central vacuole shrinks,
cell collapses, plant wilts
-plasmolysis- loss of turgor pressure
Problems:
1. Why does saltwater dry out cells?
Osmosis is the
movement of water
Inside:
10%salt, 90% water
Outside:
20%salt, 80% water
Water moves from high
to low so it moves out
of the cell.
2. Why was salt used to preserve meat?
It created a hypertonic environment, drew moisture
out of bacteria, and the meat was safe
3. Why does gargling with salt water help ease sore
throat pain?
It draws water out of the cells, reducing swelling
4. Why do they spray water on vegetables in the
grocery store?
It creates a hypotonic environment, water diffuses
into the cells, keeping them crisp
5. What will happen to the cell in each of the
following solutions?
the cell is 10% salt
Cell is 90% water
A) pure water
A) Solution is 100% water,
hypotonic, water moves in
B) 10% saltwater
B) Solution is 90% water,
isotonic, No change
C) 15% saltwater
C) Solution is 85% water,
hypertonic, water moves out
Another type of passive transport:
3. Facilitated Diffusioncarrier proteins assist larger
molecules across a membrane
from high to low concentration
Glucose enters the cell this way
4. Ion Channels • Ions move through the membrane
from high to low concentration
through channel proteins
• Each protein has a specific shape,
fits only one type of ion
Active Transport
using energy (ATP) to move molecules
from low to high concentration
1.Sodium Potassium Pump:
- uses carrier proteins to move
3 Na+ out of the cell and
2 K+ into the cell
- this creates a build up of charge,
allowing an electrical impulse to
jump from nerve cell to nerve cell
speed: 450 Na+ out and 300 K+ in
each second
2. Endocytosis – cells use energy to
ingest fluids or large particles
Steps:
1. a pouch forms in the membrane
2. material enters the pouch
3. the pouch pinches off, forming a vessicle.
Pinocytosis – ingesting fluid
Phagocytosis – ingesting particles or whole cells
Endocytosis
Exocytosis
3. Exocytosis –
reverse of endocytosis
• Substances packaged by the
Golgi leave the cell this way