transport across a cell membrane the makeup of a cell membrane effects its permeability three...
TRANSCRIPT
![Page 1: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/1.jpg)
Transport Across a Cell Membrane
• The makeup of a cell membrane effects its permeability
• Three factors determine whether or not a substance is easily able to cross a cell membrane:
• 1. Polarity
• 2. Charge
• 3. Size
![Page 2: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/2.jpg)
Passive Transport• Passive transport involves the
movement of material across the cell membrane without the input of energy on the part of the cell
• There are three basic forms of passive transport:
• 1. Simple diffusion
• 2. Facilitated diffusion
• Osmosis
![Page 3: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/3.jpg)
Simple Diffusion
• Diffusion is the random movement of particles from areas of high concentration to areas of low concentration
• Simple diffusion of material across a cell membrane occurs only with substances that can move easily across a cell membrane
![Page 4: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/4.jpg)
Facilitated Diffusion
• For molecules that, due to certain characteristics, are not able to simply diffuse across a cell membrane the movement may be aided (facilitated) by carrier proteins that provide an environment acceptable to the movement of these molecule along a concentration gradient
![Page 5: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/5.jpg)
Facilitated Diffusion• Carrier proteins never provide an open
channel across the cell membrane
![Page 6: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/6.jpg)
Passive Transport
![Page 7: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/7.jpg)
Osmosis
• Osmosis is the diffusion of water across a selectively permeable membrane in response to differences in solute concentration between the ECF and the protoplasm
• Water will diffuse from the area of higher water concentration to the area of lower water concentration
![Page 8: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/8.jpg)
Equilibrium
• Once the contraction of water become equal on both sides of the membrane the system has reached equilibrium
• Water molecules will continue to move between the two sides but there will be no net movement of water at equilibrium
![Page 9: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/9.jpg)
Isotonic Solutions
• These are solutions in which the solutes concentration outside the cell is equal to that inside the cell
• The major function of blood is to keep your internal environment in an isotonic balance called homeostasis (the maintenance of a constant environment despite internal and external changes)
![Page 10: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/10.jpg)
Hypotonic Solutions
• A hypotonic solution has a lower solute concentration (higher water concentration) than inside a cell
• This results in a net movement of water into the cell
• If the hypotonic solution is maintained it will result in excess water movement into a cell causing it to explode (hemolysis/turgor)
![Page 11: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/11.jpg)
Hypertonic Solutions
• A hypertonic solution has a higher solute concentration (lower water concentration) and inside a cell
• This results in a net movement of water out of the cell
• If the hypertonic solution is maintained it will result in excess movement of water out of the cell causing it to shrink (crenelation/plasmolysis)
![Page 12: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/12.jpg)
• http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm
![Page 13: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/13.jpg)
Active Transport
• Active transport is the movement of materials across a cell membrane against their concentration gradient with the expenditure of energy in the form of ATP
• There a three main types of active transport:
• 1. Ion pumps• 2. Co-transport• 3. Endocytosis
![Page 14: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/14.jpg)
Ion Pumps• Primary active transport involves using
energy (through ATP hydrolysis) at the membrane protein
• This causes a change in the shape of the protein that results in the transport of the molecule through the protein.
• AN example of this is the Na+-K+ pump. • The Na+-K+ pump is an antiport, it
transports K+ into the cell and Na+ out of the cell at the same time, with the expenditure of ATP
![Page 15: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/15.jpg)
Ion Pump• Ion pump moves sulphur ions across
membrane
![Page 16: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/16.jpg)
Sodium Potassium Pump
![Page 17: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/17.jpg)
Co-Transport• Other transporters use the energy
already stored in the gradient of a directly-pumped ion
• First direct active transport of the ion establishes a concentration gradient.
• Then this concentration gradient uses facilitated diffusion to pass the ion back into the cell
• The ion’ passage through a integral protein pumps some other molecule or ion along with it against its gradient
![Page 18: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/18.jpg)
Co-Transport
![Page 19: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/19.jpg)
• http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html
![Page 20: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/20.jpg)
Endocytosis
• Endocytosis is the process by which cells take in very large molecules
• There are two types of endocytosis:
1. Pinocytosis, where cells take up dissolved molecules by engulfing small amounts of the external solution
(Cells of the small intestine take up fat droplets via pinocytosis.)
![Page 21: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/21.jpg)
2. Phagocytosis, the process by which cells engulf solid particles from the external environment.
![Page 22: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/22.jpg)
Exocytosis• Exocytosis is the process by which
large molecules held within the cell are transported to the external environment (waste, proteins and other products of cellular functions)
• Small vesicles break off from the Golgi apparatus and move toward the cell membrane.
• The vesicles fuse with the cell membrane and the material is released into the external environment
![Page 23: Transport Across a Cell Membrane The makeup of a cell membrane effects its permeability Three factors determine whether or not a substance is easily able](https://reader035.vdocuments.site/reader035/viewer/2022062718/56649ea05503460f94ba3d70/html5/thumbnails/23.jpg)
Exocytosis