cell transport. define these terms: 1. solute*2. solvent * 3. semipermeable membrane* 4. passive...
TRANSCRIPT
CELL TRANSPORT
Define these terms:
1. Solute * 2. Solvent *
3. Semipermeable Membrane*
4. Passive Transport* 5.Active Transport*
6. Diffusion* 7. Osmosis*
8. Concentration Gradient
9. Facilitated Diffusion
10. Hypertonic 11. Hypotonic
12. Isotonic
Research the Following
How do molecules get into the cell?
•By crossing the Cell Membrane!
What is a key property of the Cell Membrane?
• Selective Permeability!!• This property of biological
membranes allows some substances to cross more easily than others.
How much energy will it cost the cell to MOVE molecules in
or out? • It depends on HOW it enters the cell!
• Which do you think does NOT “cost” the cell energy- Passive Transport or ActiveTransport?
PASSIVE TRANSPORT
First type Passive Transport- Diffusion
• What is it?
–Random movement of molecules down a concentration gradient from an area of high concentration to an area of low concentration.
• NO energy is expended.
Diffusion
Watch this animation!
• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html
• http://www.indiana.edu/~phys215/lecture/lecnotes/diff.html
2nd type Passive Transport- Osmosis
• The diffusion of water across selectively permeable membranes.
• Water moves from a high water concentration to low water concentration.
• NO energy expended by cell
3nd type passive transport Facilitated Diffusion
Type which uses transport proteins to move molecules across the membrane WITHOUT any energy expended by cell!
Question:What’s in a Solution?
Answer:
• solute + solvent solution
• NaCl + H20 saltwater
Hypertonic• A solution with greater solute concentration
(less water) compared to another solution.
3% NaCl97% H2O
Red Blood Cell
5% NaCl
95% H2O
solution
Hypotonic
• A solution with lower solute concentration (more water) compared to another solution.
3% Na97% H2O
Red Blood Cell
1% Na99% H2O
solution
Isotonic
• A solution with an equal solute concentration compared to another solution.
• This solution is said to be in equilibrium.
3% Na97% H2O
Red Blood Cell
3% Na97% H2O
solution
Movement of H2O = OSMOSIS!
• Water will “ALWAYS” diffuse down a concentration gradient from a HYPOTONIC solution (more water, less solute) to a HYPERTONIC solution (less water, more solute).
ALWAYS REMEMBER- water moves from• HYPOTONIC HYPERTONIC
Animal Cells
• Animal cells placed into a hypotonic solution will EXPLODE.
Hypotonic
RedBloodCell
Animal Cells
• Animal cells placed into a hypertonic solution will SHRIVEL.
Hypertonic
RedBloodCell
Plant Cells• In a hypotonic environment, the vacuole is full
of water (cell gains water), and the cell membrane is pushed against the cell wall. The cell wall helps the plant cell retain its shape under the tension.
WaterWater
CellWall Water
CentralVacuole
Plant Cells• In a hypertonic environment (loss of water),
the plasma membrane pulls away from the cell wall (vacuole empty).
Water Water
CellWall Water
plasma membrane
Active Transport
• The movement of molecules (small or large) across the plasma membrane using energy (ATP).
Examples of Active Transport:
Active transport using a carrier molecule in the membrane
- many times, this involves moving molecules from a low to high concentration (OPPOSITE the direction during diffusion!).
- Requires ATP (ENERGY!!) to move it across!
Protein pumps
• Some membrane proteins use energy to pump substances in and out of the cell.
• Sodium potassium pump animation.
• How are large molecules transported into and out of the cell?
• Endocytosis and Exocytosis (BOTH are active transport!)
Endocytosis• ENTRY into cell
• Portion of the membrane surrounds or engulfs a macromolecule (large molecule) outside cell. The membrane pinches off to form a vesicle in the cytoplasm
• Requires Energy!!
Endocytosis, cont.Different names for type macromolecules
endocytosed:
–Pinocytosis: endocytosis of liquids–Phagocytosis: endocytosis of
particles – http://www.stolaf.edu/people/giannini/flashanimat/cellstructures/phagocitos
is.swf
Exocytosis:
• EXPORT of materials OUT of the cell (wastes, cell products)
- Also a type of Active Transport (energy required!!)
Quick Quiz• 1. Which type of transport REQUIRES
energy? • 2. Which type of transport does NOT
require energy?• 3. In a Hypertonic solution, the amount of
solute is _________ in the solution than the solute concentration inside the cell.
• 4. In an Isotonic solution, the amount of solute is __________ the solute concentration inside the cell.
Quick Quiz, cont.
• 5. Movement of macromolecules OUT of the cell is called __________. Does this require energy?
• 6. Endocytosis that involves movement of liquids into the cell is called ______________. Does this require energy?
MODELLING A CELL MEMBRANE
Plastic baggies are a lot like cell membranes; they are semipermeable.
• Do baggies allow any of the following - water, starch, or iodine - to move through them?
• Materials:1.baggies2.Starch suspension
in H2O3.Iodine solution4.Beakers
DO Now!
• Sheet 3.5–Complete and we will discuss it
Concentration ProblemsIn each problem below, the membrane is
permeable to water only!
1. Which way will water move – into or out of the body cell? (draw an arrow!)
2. The solution is ________.
3. Which way will water move – into or out of the sphere? (draw an arrow!)
4. Is the solution in the beaker hypotonic, isotonic, or hypertonic compared to the cell? (Circle one!)
5. Which way will water move – into or out of the sphere? (draw an
arrow!)
6. What will happen to the shape / size of the sphere? What is the solution outside the cell?
Cell
0.45 M
solute
7. Which way will water move – into or out of the body cell? (draw
an arrow!)
8. What is the cell’s solute concentration after dynamic equilibrium is reached?
0.35 M solute
9. Which way will water move – into or out of the body cell? (draw an
arrow!)
cell
10. What is the cell’s water concentration after dynamic equilibrium is reached?
Wrap up of Transport across a Semipermeable membrane!
• BEFORE you get your beaker, write down what you EXPECTED to happen? (Who moved across the plastic membrane?)
How did your experiment work? • Did the liquid in the beaker or the
baggie change color? What does it indicate?
• Decide WHICH molecules were transported- water, iodine, or starch?
• Did your experiment test all 3 components?
Cont….• Things to think about:
–Size of atoms/ molecules–Set-up of experiment- could you
detect movement of ALL molecules?–Validity/ reliability
• How is the baggy LIKE a cell membrane?
• How is it NOT LIKE a cell membrane?
Wrap-up!• Standard 10.1: FUNDAMENTAL life
processes depend on the physical and chemical activities of the cell.–D30. Explain the role of the cell
membrane in supporting cell functions.• What ARE the roles of the cell
membrane?
Wrap-up!
How is the cell membrane structured to ensure efficiency and survival?