7-3 cell boundaries
DESCRIPTION
7-3 Cell boundaries. Cell membrane. Define: The cell membrane regulates what enters and leaves the cell and also provides protection and support . Composition: Made up of a double-layered sheet called a lipid bilayer - PowerPoint PPT PresentationTRANSCRIPT
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7-3 CELL BOUNDARIES
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CELL MEMBRANE
• Define: The cell membrane regulates what enters and leaves the cell and also provides protection and support.
• Composition: Made up of a double-layered sheet called a lipid bilayer
• The lipid bilayer gives the cell membrane a flexible structure that forms a strong barrier between the cell and its surroundings.
• The lipid bilayer also includes proteins used to channel molecules across and carbohydrates for communication.
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CELL WALL• The main function of the cell wall is to provide support and protection for the cell
• Plant cell walls are made up of cellulose
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QUICK REVIEW• Solution – A mixture of two or more substance
• Solvent – The liquid in which a solute is dissolved to form a solution
• Solute – The substance dissolved in the solution
• Concentration – The mass of a solute found in a volume of solution. Mass / Volume (g/L)
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• Transport across a membrane that requires the cell to use NO energy
• Transport across a membrane that requires the cell to use energy
TRANSPORT
Active Passive
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DIFFUSION
• Diffusion is the process of particles moving from an area of high concentration to an area with low concentration
• When the concentration of the solute is the same throughout a system, the system has reached equilibrium
• Because diffusion depends upon random particle movement, substances diffuse across membranes without requiring the cell to use energy
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• Diffusion does not require energy!
DIFFUSION
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FACILITATED DIFFUSION
• Few molecules are too big to get through the membrane by themselves.
• Facilitated: Make an action or process easier.
• Facilitated diffusion: Molecules that cannot normally pass through the cell membrane get help using their own personnel protein channel.
• NO ENERGY REQUIRED!!!
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ACTIVE TRANSPORT
• Uses energy
• Generally carried out by transport proteins or “pumps”
• “Pumps” work pumping concentration from low to high. (Backwards from normal)
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• Most biological membranes are selectively permeable. Only allowing some substances through and denying others.
• Osmosis is the diffusion of water across a selectively permeable membrane.
OSMOSIS
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HOW OSMOSIS WORKS
• Movement of WATER from an area of high concentration to an area with low concentration.
• Water will continue to move across a membrane until equilibrium is complete.
• Isotonic – Same strength of solute
• Hypertonic – Above strength of solute
• Hypotonic – Below Strength of solute
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OSMOTIC PRESSURE
• For cells to survive, they must find a way to balance the intake and outtake of water.
• If balance is not met, a force called osmotic pressure occurs. Creating a situation where cells will struggle to survive.
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ENDOCYTOSIS • Process of taking material into the cell by means of infolding or pockets.
• Pocket breaks loose and forms a vacuole.
• Two main types of endocytosis
• Phagocytosis
• Pinocytosis
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PHAGOCYTOSIS
• “Cell Eating”
• Cell slowly surrounds and engulfs the food.
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PINOCYTOSIS
• “Cell Drinking”
• Cells form tiny pockets around the cell wall and fill them with liquid and pinch off
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EXOCYTOSIS
• Removal from the cell
• Vacuole fuses with the cell membrane, forcing the contents out of the cell
• Contractile vacuole in some fresh water protists.