cellular transport. all particles move and have kinetic energy (energy of motion). movement is...
TRANSCRIPT
Cellular Transport
Cellular Transport
• All particles move and have kinetic energy (energy of motion).
• Movement is random and usually in a water solution.• Cells are mostly made of water and there is a constant flow of ions and particles.
IV. 2 Types of Cellular Transport
1.Passive transport = movement of molecules across the membrane by using the molecules kinetic energy. The cell exerts NO energy!
2.Active transport = transport of materials against the concentration gradient and requires cellular energy.
V. Passive Transport
• 3 types of passive transport:
1. Diffusion = the net movement of particles from an area of HIGHER concentration of particles to an area of LOWER concentration of particles.
Diffusion…
• Molecules move randomly until they are equally distributed.
• Diffusion continues until the concentration of substances is uniform throughout.
Diffusion…
• Dynamic equilibrium – continual movement but no overall change in the concentration; •Movement of materials into and out of the cell at equal rates maintaining dynamic equilibrium with its environment.
Diffusion…
• Diffusion depends on the concentration gradient.• Concentration gradient is the
difference between the concentration of a particular molecule in one area and the concentration in an adjacent area.
• Ex: gas exchange in the lungs (oxygen from air to blood and carbon dioxide from blood to air).
V. Passive Transport
2. Facilitated Diffusion = type of passive transport that increases the rate of diffusion with the use of carrier proteins.• Ex: Facilitated diffusion of glucose.
Facilitated Diffusion
How facilitated diffusion works
• http://www.youtube.com/watch?v=I4123hUU8xo
V. Passive Transport
3. Osmosis = the diffusion of water molecules from an area of HIGH water concentration to an area of LOW water concentration.
V. Passive Transport: OSMOSIS
• Occurs in response to the concentration of solutes dissolved in water! • Solutes are dissolved substances in
a solution.• Cytoplasm is mostly water
containing many dissolved solutes.
V. Passive Transport: OSMOSIS
• Because no TWO molecules can occupy the same space at the same time, the MORE solutes there are in a certain volume of water; the FEWER water molecules there can be in the same water.
V. Passive Transport: OSMOSIS
• Plant and animal cells behave differently because plant cells have a large water vacuole and a cell wall.
How OSMOSIS works
• http://www.youtube.com/watch?v=w3_8FSrqc-I
V. Passive Transport: OSMOSIS
• Ex: Osmosis occurring in a slug (animal) cell.
V. Passive Transport: OSMOSIS
A.Isotonic solution = a solution in which the concentration of dissolved substances (solutes) is the SAME as the concentration of solutes inside the cell.
Osmosis DOES NOT occur since a concentration gradient
is not established.
What happens to cells when placed in an isotonic solution?
• Plant cell – becomes flaccid (limp)• Plant wilts because no net tendency
for water to enter
• Animal cell - normal
Animal cell Plant cell
V. Passive Transport: OSMOSIS
B. Hypotonic solution = a solution in which the concentration of solutes is LOWER than the concentration of solutes inside the cell.
What happens to cells when placed in a
hypotonic solution?
• Animal cell – water will move thru plasma membrane into the cell. This causes the cell to swell and the internal pressure increases.• Cell lyses (bursts)!
What happens to cells when placed in a hypotonic solution?
• Plant cell – normal• The vacuole and cytoplasm increase
in volume• The cell membrane is pushed harder
against the cell wall causing it to stretch a little.• The plant tissue becomes stiffer
(turgid).
V. Passive Transport: OSMOSIS
C. Hypertonic solution = a solution in which the concentration of dissolved substances is HIGHER than the concentration inside the cell.
What happens to cells when placed in a
hypertonic solution?
• Animal cell – will shrivel because of decreased turgor pressure.
What happens to cells when placed in a hypertonic solution?
• Plant cell – will lose water from vacuole and a decrease in turgor pressure will occur; so it is plasmolyzed.• Turgor pressure = internal pressure of a
cell due to water held there by osmotic pressure• Plasmolysis = the loss of turgor pressure
causing the plasma membrane to pull away from the cell wall• Causes the plant to wilt
D. Summary of Cell Behavior in Different Environments:
OSMOSIS PROBLEMS
First we need to understand 2 vocab words:
1. Solute – the substance that dissolves (salt, sugar)
2. Solvent – the substance in which the solute dissolves (water)
How to work osmosis problems
• https://www.youtube.com/watch?v=7E_qjzvCtNA
OSMOSIS PROBLEMS
Cell: 5% salt (solute) Environment: 0% salt (solute)
OSMOSIS PROBLEMS
Cell: 25% salt (solute) Environment: 30% salt (solute)
OSMOSIS PROBLEMS
Cell: 45% salt (solute) Environment: 45% salt(solute)
VI. Active Transport
• Movement of molecules from an area of LOW to an area of HIGH concentration. (opposite of passive transport!)
• REQUIRES cellular energy!
• Moves large, complex molecules such as proteins across the cell membranes.
How active transport works
• http://www.youtube.com/watch?v=yz7EHJFDEJs
VI. Active Transport
• Large molecules, food, or fluid droplets are packaged in membrane-bound sacs called vesicles.
2 types of active transport
1. Endocytosis = process in which a cell surrounds and takes in material from its environment• Used by ameba to feed and white
blood cells to kill bacteria
2 types of active transport
2. Exocytosis = expels materials out of the cell, reverse of endocytosis
• Used to remove wastes, mucus, and cell products
• Proteins made by ribosomes in a cell are packaged into transport vesicles by the golgi apparatus
• Transport vesicles fuse with the cell membrane and then the proteins are secreted out of the cell (ex: insulin)
Exocytosis
How endocytosis and exocytosis works
• http://www.youtube.com/watch?v=DuDmvlbpjHQ
Identify the following….
Two types of endocytosis:
1. Pinocytosis – cell engulfs small particles such as fluids and solutes.
• Called “cellular drinking”
2. Phagocytosis – cell engulfs large particles such as bacteria, viruses, and other cells.
• Called “cellular eating”• Our white blood cells perform phagocytosis
Sodium Potassium Pump
• Form of active transport that uses a protein and energy to pump 3 Na+ out of the cell and 2 K+ into the cell against the concentration gradient.
Review video
• Watch the video and fill out the worksheet!
• http://www.bozemanscience.com/016-transport-across-cell-membranes