Transcript Moving cellular Material Notes

Warm Up
Write your responses in your binder:
1. What materials need to get into a cell?
Why?
2. What materials need to get out of a cell?
Why?
3. What cell structure must these materials
pass through?
Foldable:
Passive Transport
Active Transport
Cellular Transport
Cellular Transport
• Remember: All living things use energy.
– So, materials such as food, water, and oxygen need to get
into cells.
– Additionally, wastes, such as carbon dioxide, needs to get
out of cells.
• Homeostasis – the maintenance of stable internal
conditions inside of the cell
The Cell Membrane
• The exchange of materials between the cell
and its environment takes place at the cell’s
membrane.
– Selectively permeable (or semipermeable) –
selects or chooses what materials may pass
through (or permeate)
• Two general types of cellular transport:
1. Passive transport
2. Active transport
I. Passive Transport
• Passive transport is the movement of materials
through the cell membrane WITHOUT the use of
energy.
• Two types:
– Diffusion
– Osmosis
1. Diffusion
• Diffusion
– The movement of small particles through the cell
membrane from areas of high concentration
(crowded) to areas of low concentration (less
crowded).
• Particles are constantly moving
• Does NOT require that the cell use any energy
Cell
membrane
over time…
Area of higher
concentration
Area of lower
concentration
Diffusion
Before diffusion – particles
are crowded outside the cell
and some move into the cell.
After diffusion– particles
have reached equilibrium.
Facilitated Diffusion
(Accelerated)
• Some substances, such as
glucose (a sugar) cannot
move through the
phospholipid cell
membrane.
• They are “helped” through
the cell membrane by
transport proteins.
Transport Proteins-Two Types
• Carrier proteins: carry large molecules such as
the glucose molecule glucose, through the cell
membrane.
• Channel proteins : Channel proteins form
pores through the membrane. Atomic
particles, such as sodium ions and potassium
ions, pass through the cell membrane. Also
known as Sodium-potassium pump.
2. Osmosis
• Diffusion of water is so important to life
processes that it has been given a
special name…Osmosis – the
diffusion of water
(Think…H20 = osmosis)
• Water is made up of particles, called
molecules (H2O).
• Pure water = has a higher concentration of
water molecules
• Mixture in water (solution) - has a lower
concentration of water molecules
• Ex: food coloring, sugar, or salt mixed in water
Osmosis
Affect of Water on Red Blood Cells
A. Normal
B. Salt water
C. Too much “pure” water
Warm Up
• The cell membrane of
this cell is permeable to
water but not to
dissolved materials
(solutes). What will
immediately happen
when the cell is placed
into this solution?
A.
Water will flow out of the
cell.
B. Water will flow into the cell.
C. Dissolved materials will move
into the cell.
D. Dissolved materials will move
into the cell AND water will
move out.
= dissolved materials
II. Active Transport
• When cells use energy to move materials
through the cell membrane, it is called active
transport.
– Movement of small molecules from LOW to HIGH
concentrations (LESS CROWDED to CROWDED
areas).
– Movement of large molecules into or out of the
cell.
Moving Small Particles
• Movement from LOW
to HIGH concentrations
of a substance
• Cells can take in
needed nutrients from
the environment
through carrier
proteins by using active
transport.
Moving Large Particles
• Large particles move into and out of cells through:
– Endocytosis – cell surrounds a large particle and encloses
the particle in a vesicle to bring the particle into the cell.
• Vesicle – sacs formed from pieces of the cell membrane
• Endo = inside
Example: some cells take in bacteria and viruses using
endocytosis
– Exocytosis – when large particles leave the cell through
the cell membrane
• Exo = exit; outside
ENDOCYTOSIS - into
EXOCYTOSIS – out of
TOC #36 “Cellular Transport Analogy Chart”
Characteristic
Molecule Movement
Uses
Energy?
Passive Transport
Active Transport
(Diffusion & Osmosis)
(Transport proteins,
endocytosis, exocytosis)
High to Low
(crowded to less crowded)
1. Low to High
(less crowded into a
crowded area)
No
2. Large particles
Yes
Rowing with the current
Rowing against the
current
Cycling downhill
Cycling uphill
Analogies