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“Materials move across the cell’s membranes”
Section 2.3
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Do Now!! What is the purpose of the cell membrane?
What would happen if we didn’t have cell membranes? What goes in and out of our cells?
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Objectives To explain the different functions of the macromolecules in the plasma membrane. To understand the process of diffusion. To compare and contrast active and passive transport.
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The Cell Membrane Called a “Fluid Mosaic Model”
Proteins and other components embedded like a mosaic Qqsf_UJcfBc
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Membrane Components Phospholipids:
Give the general structure of the membrane
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Please draw a phospholipid!
Draw a phospholipid and label its parts!
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Membrane Components Proteins: Allow bigger substances to pass through
Provide structure: Microtubules and microfilaments (cytoskeleton)
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Membrane Components Cholesterol: helps maintain structure of phospholipids prevents the tails from sticking together
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Membrane Components Carbohydrates: receptors that send and receive signals from other cells Attached to glycolipids and glycoproteins
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Types of Transport across a cell membrane
Passive Transport Active Transport Vesicular Transport
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Passive Transport Does NOT require energy
Molecules go from an area of high concentration to an area of low concentration “Go with the flow”
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3 Types of Passive Transport
Diffusion Facilitated Diffusion Osmosis
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What is diffusion? Movement of particles from area where there are many to area where there are fewer From high to low concentration
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What is diffusion? Molecules move from high concentration to low concentration to create DYNAMIC EQUILIBRIUM Concentrations are the same in all areas
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Affected By… Heat- higher temp increases rate State of Matter
Solid- slow Liquid- faster Gas- fastest Size and Concentration Bigger= slower More concentration = faster
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Do Now!! Explain what happens when you put a sugar cube in your tea in regards to diffusion.
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Objectives Explain facilitated diffusion
Define solute, solvent and solution Identify different types of solutions Participate in a diffusion dialysis tubing demo
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Explain what’s happening…
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Facilitated Diffusion
Certain molecules need a “helper” or “facilitator” to allow them to cross the membrane when they are too big.
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Osmosis The flow of WATER from a high concentration to a low concentration
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Solution A mixture in which you cannot separate the components (ex: iced tea) solute: the substance being dissolved Ex: iced tea powder solvent: The substance doing the dissolving Ex: water
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Isotonic Solutions Blood Cell Plant Cell
Same amount of solute inside the membrane as there is outside. Cell in this solution: NOTHING Blood Cell Plant Cell
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HYPERtonic Solutions More solute, less water on outside of the membrane Cell in this solution: shrinks/shrivels
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HYPOtonic Solutions Less solute, more water on outside of membrane
Effect: cell swells or bursts! /
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Identify the type of solution!
Cell in ________ Solution Cell in ________ Solution Cell in ________ Solution H2O H2O H2O
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Answer key! Cell in hypotonic Solution Cell in isotonic Solution
Cell in hypertonic Solution H2O H2O H2O
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Let’s try another… For the following examples:
Which way is the water moving? What kind of cell solution (outside)? What is going to happen to the cells? A. B. C. 12% Salt 9% Salt 28% Salt 18% Salt 2% Salt 3% Salt
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Real life osmosis situations
A salt water fish is put into a freshwater aquarium. What type of solution is the freshwater? What is going to happen to the cells of the fish?
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Real life osmosis examples
A patient is given an IV, which contains the perfect balance of saline What type of solution is in the IV? What is going to happen to the cells of the human?
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Real life osmosis examples
Your garden is infested with slugs so you go around pouring salt on them What type of solution is this salt? What is going to happen to the cells of the slug? (don’t do this to the poor slugs )
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Active Transport When molecules move from a low concentration to a high concentration and must use ENERGY. Example- Sodium Potassium Pump hill.com/sites/ /student_view0/chap ter2/animation__how_the_sodium_potassium_ pump_works.html
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Vesicular Transport Sometimes things enter and exit the cell by forming vesicles. For example… Endocytosis: When cells absorb molecules by engulfing them. (like pacman)
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Endocytosis Pinocytosis: when the substance being engulfed is a LIQUID. Phagocytosis: when the substance being engulfed is a SOLID.
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Vesicular Transport Exocytosis: When cells expel unwanted materials from vesicles.
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Vesicular Transport
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