cellular transport how molecules are transported across the cell membrane
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Cellular Transport How Molecules Are Transported Across The Cell Membrane. Essential Questions. How do cells maintain homeostasis? How are cell membranes (plasma membranes) selectively permeable (semi-permeable)? - PowerPoint PPT PresentationTRANSCRIPT
Cellular Transport
How Molecules Are Transported Across The Cell Membrane.
Essential Questions• How do cells maintain homeostasis?• How are cell membranes (plasma
membranes) selectively permeable (semi-permeable)?
• Why is it important that cells are able to transport molecules with (active transport) and without (passive transport) energy?
Passive Transport• Cell uses no energy • Random movement of particles
along a concentration gradient from an area of high concentration to an area of low concentration.
– (HighLow)• Concentration gradient -
difference in the concentration of substance from one area to another.
• Three types:
3 Types of Passive Transport
1. Diffusion2. Facilitative Diffusion3. Osmosis
1. Diffusion• Diffusion: -random
movement of particles from an area of high concentration to an area of low concentration.
– continues until all molecules are evenly spaced or at equilibrium (equal)
Simple Diffusion Animation
• Facilitated diffusion: diffusion of specific particles along concentration gradient (High Low) with help proteins in membrane. a.Carrier Proteins -bind to
specific molecules to carry across membrane.a.Transport large particles
that can’t pass through on own. Ex. Glucose
b.Ion Channels Protein - transports ions (charged particles) through a polar pore.a.Ex. Na+, K+, Cl-
Facilitated
diffusion (Channel Protein)
Diffusion
(Lipid Bilayer
)
: 2. Facilitated
Diffusion
Carrier Protein
A B
• http://bio.winona.edu/berg/Free.htm
High Concentration
Low Concentration
Cell Membrane
Glucosemolecules
Proteinchannel
Facilitated Diffusion
Go to Section:
Transport ProteinThrough a
Cellular Transport From a- HigHig
hh
LowLow
• Channel Proteins animations
• Osmosis: diffusion of water through a selectively permeable membrane– Moves from a high
concentration of water to a low concentration of water
• Cell cannot control movement of water through cell membrane as water too small and in such abundance.
Osmosis animation 3. Osmosis
Effects of Osmosis on Life• Water moves freely through
pores.• Substances dissolve well in water.
– Solute: what is being dissolved– Solvent: what dissolves the
solute• In salt water, the solute is the salt
and the solvent is the water• Cells can be placed in 3 kinds
of water solutions that affect their homeostasis.
Hypotonic Solution
Hypotonic: Solution has a lower concentration of solutes and a higher
concentration of water than inside the cell. (Low solute; High water)
Result: Water moves from the solution to inside the cell: Cell Swells and bursts open
( called lyse)!
• Osmosis Animations for
isotonic, hypertonic, and
hypotonic solutions
Hypertonic Solution
Hypertonic: Solution has a higher concentration of solutes and a lower
concentration of water than inside the cell. (High solute; Low water)
Result: Water moves out of the cell into the solution: Cell shrivels or
shrinks!
• Osmosis Animations for
isotonic, hypertonic, and
hypotonic solutions
shrinks
Isotonic SolutionIsotonic: Concentration of solutes in the solution is equal to the concentration of
solutes inside the cell.
Result: Water moves equally in both directions and the cell remains same size!
(Dynamic Equilibrium)
• Osmosis Animations for
isotonic, hypertonic, and
hypotonic solutions
In what type of solution are these cells?
A CB
Hypertonic
Isotonic
Hypotonic
Real Life Examples
If you are stranded in the ocean, should you drink the water to stay alive?
Why do we wrinkle when we are in the tube too long?
Why does it help to gargle salt water when we have a
sore throat?
What happens to a snail when you put salt water on
it?