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The Cell and Its Environment
Chapter 7 The Cell and Its Environment The Cell Theory All Organisms are made from one or more cells. The cell is the basic unit of structure and function in organisms. All cells are produced from other cells.
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Plasma Membrane What is it? What is its purpose?
Boundary that separates the cell from its environment. What is its purpose? Controls which particles enter and leave the cell Amino Acids Glucose Carbon Dioxide This is Called “Selective Permeability” The membrane only allows particles that are used by the cell or expelled to cross the membrane
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The plasma membrane is made up of a lipid bilayer.
What is a lipid bilayer? Composed of Phospholipids - two layers of phospholipids form the plasma membrane One end is water soluble – Phosphate group The other end is nonsoluble. – Fatty acid end
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Visual of the Lipid Bilayer
Phospholipid
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Make up of the Plasma Membrane
What’s the basic structure of the Plasma Membrane? Lipid Bilayer Inside of the Lipid Bilayer are: - Proteins – allow for transport of molecules - allow for chemical reactions - Carbohydrates – Recognition molecules - Cholesterol – helps separate the fatty acid ends
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Visual of the Plasma Membrane
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Visual of the Plasma Membrane
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Fluid Mosaic Model Why doesn’t it break apart?
What does it mean to be “fluid”? What is mean to be “Mosaic”? The components of the membrane are constantly moving Why doesn’t it break apart? Phospholipids are: Hydrophilic – Polar ends – attracted to H20 (dissolves) Hydrophobic – nonpolar end – not attracted to H20 (does not dissolve)
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Visual of the Fluid Mosaic Model
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Membrane Function Diffusion?
Random movement of particles from a greater concentration to a region of lesser concentration Until “dynamic equilibrium”
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Osmosis What is it? The diffusion of water into and out of cells across a selectively permeable membrane Cells must maintain Osmotic Balance. Why?
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More Osmosis
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Even More Osmosis
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cell cell H2O Lysed Turgid (normal) Isotonic solution
Fig. 7-13 H2O Lysed Turgid (normal) Isotonic solution Hypotonic solution H2O Normal Flaccid H2O Shriveled Plasmolyzed Hypertonic solution (a) Animal cell (b) Plant cell
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Facilitated Diffusion
The transport of particles across the plasma membrane with the use of transport proteins. Channel Proteins (Pores) - Allow transport of ions - They are specific to the size and charge of the ions Carrier Proteins – two types - change shape to allow certain molecules to cross the plasma membrane 2. Gates – one particle attaches to the carrier protein changing its shape – allowing particles to freely pass across the membrane.
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Visual of Facilitated Diffusion
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More Facilitated Diffusion
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Active Transport Movement of particles from an area lesser concentration to an area of greater concentration The transport proteins for active transport are called “pumps” It costs the cell energy – that’s the difference between facilitated and active transport
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Visual of Active Transport
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Review Passive & Active Transport
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Endocytosis and Exocytosis
Endocytosis – the plasma membrane surrounds and takes in substances from the environment Exocytosis – removal of substances from the cell, opposite of Endocytosis
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Endocytosis – Phagocytosis
Phagocytosis – solid chunks of material are taken into the cell
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Endocytosis – Pinocytosis
Pinocytosis – liquid is taken into the cell
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Endocytosis – Receptor-Aided
Protein Receptors identify specific particles for endocytosis
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Endocytosis
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Review A B - In your lab groups answer the following questions.
Define part “A” and “B” of the Molecule Below. A B Explain how each part of the molecule behaves in H20?
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Draw the arrangement of Molecules that make up the plasma membrane.
Review Draw the arrangement of Molecules that make up the plasma membrane. Explain the function of each molecule. What makes the plasma membrane permeable to Water? What does it mean to be selectively permeable?
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Review What process causes water to enter a single cell organism?
What is this Process called? What would happen to a single cell pond organism that was placed into pure water? Why? What would happen to a single cell pond organism that was placed into salt water? Why?
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Review Diagram and explain the similarities and differences of the following: Diffusion, Osmosis and Facilitated Diffusion. Channel Proteins, Carrier Proteins and Gate Proteins. Phagocytosis, Pinocytosis and Receptor-aided endocytosis.
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Answer to #2 Channel Proteins (Pores) - Allow transport of ions
- They are specific to the size and charge of the ions Carrier Proteins – two types 1. change shape to allow certain molecules to cross the plasma membrane 2. Gates – one particle attaches to he carrier protein changing its shape – allowing particles to freely pass across the membrane.
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Review Explain the difference between Active and Passive Transport.
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