Transcript Cell Transport

Cell Transport
Cell Membrane- Homeostasis
They are Selectively Permeable= some
things can get in and others can not!
Role: “Gate Keeper”
Membranes control what molecules can enter
and leave the cell!
Membranes are impermeable to:
Molecules that can not get in or out:
• Ions
• Polar molecules
water
• Large molecules
glucose
amino acids
Membranes are permeable to:
Molecules that can get in and out of the cell:
• Hydrophobic molecules:
steroids
CO2 O2 N2
• Small & uncharged
urea & ethanol
Polar molecules and IonsHomeostasis
Transport proteins: allow polar molecules &
ions to move through the membrane!!
• Ions
Na+, Cl-, K+
• Polar molecules
sugar , water
Passive transport
The cell does not use energy to move
molecules across the membrane.
• Molecules naturally flow from areas of high
concentration to areas of low concentration.
Concentration Gradient
Imaginary slope that shows the direction of the
flow of molecules.
start
stop
Equilibrium
Molecules will continue to move from high to
low until they are equal on both sides of the
membrane.
Start
Stop
Three types of Passive Transport
1. Diffusion: movement of hydrophobic fluids
and gasses: Dyes, oxygen
2. Osmosis: movement of water
3. Facilitated Diffusion: requires transport
proteins: glucose
Facilitate = help
Osmosis
Water is essential to maintaining homeostasis
in the cell and the body!!
• It is polar- impermeable
• Requires a channel protein- facilitated
Aquaporin
2003 Nobel Prize -Biochemistry
Osmosis and Solutions
The intracellular and extracellular environments
of the cell determine which way water will
flow.
Cellular environment determines the
direction of water flow!
Intra= inside or within
Extra= outside
Solution
A solution is the sum of the solute and solvent.
Solute: something that can dissolve: sugar, salt
Solvent: the dissolver: water
How are the solutions in the beaker similar and different?
Direction water flows
The solute concentration on both sides of the
cell membrane determines the direction that
water flows!!
Beaker solution = environment
Environment is relative to the cell- add cell
3 Types of Solutions
Based upon the solute ratio
outside : inside the cell.
Hypertonic solution- more solute less water than
the cell
Hypotonic solution- less solute more water than
the cell
Isotonic solution- equal solutes on both sides of the
cell membrane
Hyper= more Hypo= less Iso= equal
Hypertonic Solution
Has more solutes than
the cell = less water
water moves out of the
cell.
Salt
Water
Hypotonic Solution
Has less solute than the
cell = more water
water moves into the cell
Draw it!
Salt = S
Water = W
Isotonic Solution
Equal solutes inside and
outside the cellno net flow in or out of
the cell.
Dynamic equilibriummolecules will move in
or out of the cell but –
no net gain or loss of
water.
Cells React to Their Environment
Animal cells- lack a cell
wall and will lyse in a
hypotonic solution.
Plants cells- cell will not
burst in a hypotonic
solution – Cell Wall
Lys= break apart
Organisms, Adaptations, Osmosis
• Unicellular aquatic
animal-like organisms.
• Lack a cell wall.
Contractile vacuolepumps out excess
water to maintain
homeostasis
Sharks and Osmoregulation
What would happen to a shark
if it was placed in a
freshwater aquarium?
Exception: Bull Sharks- have
been found in the Mississippi
as far north as Illinois.
Group discussion- Questions