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Homeostasis Balanced internal condition of cells
The Plasma Membrane 12/28/2018 Homeostasis Balanced internal condition of cells Also called equilibrium Maintained by plasma membrane controlling what enters & leaves the cell G. Podgorski, Biol. 1010
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Structure of the Cell Membrane
The Plasma Membrane 12/28/2018 Structure of the Cell Membrane copyright cmassengale G. Podgorski, Biol. 1010
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Structure of the membrane is Made up of phospholipids,
Proteins and cholesterol The Plasma Membrane 12/28/2018 G. Podgorski, Biol. 1010
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A mosaic A picture made of little tiles and pieces of glass gathered and stuck together
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The Plasma Membrane FLUID MOSAIC MODEL 12/28/2018 FLUID- because individual phospholipids and proteins can move side-to-side within the layer, like it’s a liquid. MOSAIC- because of the pattern produced by the scattered protein molecules when the membrane is viewed from above G. Podgorski, Biol. 1010
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Cell Membrane Polar heads are hydrophilic “water loving”
The Plasma Membrane 12/28/2018 Polar heads are hydrophilic “water loving” Nonpolar tails are hydrophobic “water fearing” Makes membrane “Selective” in what crosses G. Podgorski, Biol. 1010
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Types of Transport Across Cell Membranes
The Plasma Membrane 12/28/2018 Types of Transport Across Cell Membranes G. Podgorski, Biol. 1010
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Passive Transport Simple Diffusion Doesn’t require energy
The Plasma Membrane 12/28/2018 Passive Transport Simple Diffusion Doesn’t require energy Moves high to low concentration Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out. G. Podgorski, Biol. 1010
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Passive Transport Simple Diffusion The Plasma Membrane 12/28/2018
G. Podgorski, Biol. 1010
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Getting through the membrane
(a) Simple diffusion © Pearson Education Ltd 2008 This document may have been altered from the original
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The Plasma Membrane 12/28/2018 DIFFUSION Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY G. Podgorski, Biol. 1010
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Diffusion through a Membrane
The Plasma Membrane 12/28/2018 Diffusion through a Membrane Cell membrane Solute moves DOWN concentration gradient (HIGH to LOW) Solute= anything that is dissolved (in water) G. Podgorski, Biol. 1010
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Diffusion of Liquids The Plasma Membrane 12/28/2018
Have beaker set up and ready to do quick demo G. Podgorski, Biol. 1010
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Facilitated diffusion
The Plasma Membrane 12/28/2018 Facilitated diffusion Doesn’t require energy Uses transport proteins to move high to low concentration Examples: Glucose or amino acids moving from blood into a cell. G. Podgorski, Biol. 1010
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Diffusion across a membrane Semipermeable membrane
The Plasma Membrane 12/28/2018 Osmosis Diffusion across a membrane Diffusion of water across a membrane Moves from HIGH to Low Is a type of passive transport Semipermeable membrane G. Podgorski, Biol. 1010
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Diffusion of H2O Across A Membrane
The Plasma Membrane 12/28/2018 Diffusion of H2O Across A Membrane High H2O potential Low solute concentration Low H2O potential High solute concentration G. Podgorski, Biol. 1010
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copyright cmassengale
The Plasma Membrane 12/28/2018 Aquaporins Water Channels Protein pores used during OSMOSIS WATER MOLECULES copyright cmassengale G. Podgorski, Biol. 1010
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Factors affecting the rate of diffusion
a steep concentration gradient, diffusion rate increases The higher the surface area to volume ratio, the faster diffusion occurs. Vs Vs
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Diffusion In a nutshell..
The larger the area and difference in concentration and the thinner the surface, the quicker the rate For example.. in the lung the surface area is made very large by the presence of many alveoli.
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Active Transport Requires energy or ATP
The Plasma Membrane 12/28/2018 Active Transport Requires energy or ATP Moves materials from LOW to HIGH concentration AGAINST concentration gradient G. Podgorski, Biol. 1010
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The Plasma Membrane 12/28/2018 Carrier Proteins Other carrier proteins change shape to move materials across the cell membrane G. Podgorski, Biol. 1010
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Examples of Active transport
Animal cells
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Place these features in the correct part of the Venn Diagram
Involves water only Requires energy Is passive Movement of particles Needs a semi-permeable membrane High to low concentration Against a concentration gradient Occurs in nature How minerals get into root hair cells How oxygen leaves a leaf How water keeps plant cells turgid Involves transport of solutes DIFFUSION OSMOSIS ACTIVE TRANSPORT
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Endocytosis – Phagocytosis
The Plasma Membrane 12/28/2018 Endocytosis – Phagocytosis Used to engulf large particles such as food, bacteria, etc. into vesicles Called “Cell Eating” G. Podgorski, Biol. 1010
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copyright cmassengale
The Plasma Membrane 12/28/2018 Phagocytosis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue) copyright cmassengale G. Podgorski, Biol. 1010
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Exocytosis- moving things out.
The Plasma Membrane Moving the “Big Stuff” 12/28/2018 Exocytosis- moving things out. Molecules are moved out of the cell by vesicles that fuse with the plasma membrane. This is how many hormones are secreted G. Podgorski, Biol. 1010
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The Plasma Membrane 12/28/2018 Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. Inside Cell Cell environment G. Podgorski, Biol. 1010
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Three Forms of Transport Across the Membrane
The Plasma Membrane Three Forms of Transport Across the Membrane 12/28/2018 G. Podgorski, Biol. 1010
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Cell in Isotonic Solution
The Plasma Membrane 12/28/2018 Cell in Isotonic Solution 10% NaCL 90% H2O ENVIRONMENT CELL NO NET MOVEMENT 10% NaCL 90% H2O What is the direction of water movement? equilibrium The cell is at _______________. G. Podgorski, Biol. 1010
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Cell in Hypotonic Solution
The Plasma Membrane 12/28/2018 Cell in Hypotonic Solution 10% NaCL 90% H2O CELL 20% NaCL 80% H2O What is the direction of water movement? G. Podgorski, Biol. 1010
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Cell in Hypertonic Solution
The Plasma Membrane 12/28/2018 Cell in Hypertonic Solution 15% NaCL 85% H2O ENVIRONMENT CELL 5% NaCL 95% H2O What is the direction of water movement? G. Podgorski, Biol. 1010
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NO NET MOVEMENT OF H2O (equal amounts entering & leaving)
The Plasma Membrane 12/28/2018 Isotonic Solution Hypotonic Solution Hypertonic Solution NO NET MOVEMENT OF H2O (equal amounts entering & leaving) CYTOLYSIS- cell busts PLASMOLYSIS- shriveling of cell G. Podgorski, Biol. 1010
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Cytolysis & Plasmolysis
The Plasma Membrane 12/28/2018 Cytolysis & Plasmolysis Cytolysis Plasmolysis G. Podgorski, Biol. 1010
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Osmosis in Red Blood Cells
The Plasma Membrane 12/28/2018 Osmosis in Red Blood Cells Isotonic Hypertonic Hypotonic G. Podgorski, Biol. 1010
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isotonic hypotonic hypertonic hypertonic isotonic hypotonic
The Plasma Membrane 12/28/2018 isotonic hypotonic hypertonic hypertonic isotonic hypotonic G. Podgorski, Biol. 1010
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