Transcript Cellular Transport Notes

Cellular Transport Notes
Cell Membrane
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
Cell Parts that are tested
frequently:
nucleus
cytoplasm
DNA
chloroplast
ribosomes
mitochondria
Cell membrane
Cell Membrane
Function of the Cell Membrane:
1. Lets things go in/out of the cell in order to
maintain-regulator- selectively permeable:
• Homeostasis
• Balance
• equilibrium
2. Recognizes other cells
3. Holds cytoplasm in the cell
How the cell membrane moves
things across the membrane and
maintains a balance in the cell
How Cell Membrane Works
No Energy (HL)
Diffusion -movement of SMALL molecules (solutes)
H
L
How Cell Membrane Works
No Energy (HL)
Osmosis- the diffusion of water through a selectively
permeable membrane by way of aqua-porins.
H
L
Semi-permeable
membrane is
permeable to water,
but not to sugar
Practice: Osmosis #1
Osmosis is diffusion of water,
therefore, we look at the
concentrations of water.
H
L
100% water
0% salt
10% salt
90% water
swell
Practice: Osmosis #2
ON YOUR OWN
Osmosis is diffusion of water,
therefore, we look at the
concentrations of water.
L
80% water
20% salt
H
10% salt
90% water
Practice: Osmosis #3
ON YOUR OWN
In equilibrium…
10% salt
90% water
10% salt
90% water
But do the water
molecules just
stop moving?
No. They move
in/out at an
equal rate.
EQUILIBRIUM!
Practice: Osmosis
Salt water fish in fresh water.
What will happen to the fish?
H
L
Fish
cells will
gain
water
and
swell
Practice: Osmosis
Fresh water fish in salt water.
What will happen to the fish?
L
H
Fish
cells will
lose
water
and
shrink
Hypertonic Solutions: contain a high concentration of solute
relative to another solution. When a cell is placed in a
hypertonic solution, the water diffuses out of the cell,
causing the cell to shrivel/shrink.
Hypotonic Solutions: contain a low concentration of solute
relative to another solution. When a cell is placed in a
hypotonic solution, the water diffuses into the cell, causing
the cell to swell and possibly explode/burst.
Isotonic Solutions: contain the SAME concentration of
solute as another solution. When a cell is placed in an
isotonic solution, the water diffuses into and out of the cell
at the same rate.
Diffusion (molecules) Across Membranes
1. Diffusion
1. Facilitated diffusion
Substances move with the concentration
gradient from high to low, but carrier molecules
speed up the movement of diffusing
substances. No energy is required.
2. Active transport
The movement of materials against the
concentration gradient from low to high
concentrations. Energy is required.
Click
• Endocytosis and Exocytosis is the mechanism by which
very large molecules (such as food and wastes) get into
and out of the cell
Food is moved into the
cell by Endocytosis
Wastes are moved out
of the cell by
Exocytosis
Ex: White Blood Cells, which are part of the immune
system, surround and engulf bacteria by endocytosis.
Sodium-Potassium Pump
• A chemical mechanism
that uses carrier proteins
and energy to move 3
sodium ions out of the
cell and 2 potassium ions
into the cell.
• The sodium potassium
pump is important for the
conduction of nerve
impulses and contraction
• of The
sodium-potassium pump can transport 450 sodium and 300
muscles.
potassium ions in and out of the cell in just one second.
•
1/3 of an animal’s at rest energy is used to power the sodiumpotassium pump!