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The Cell Membrane - Gateway to the Cell The Plasma Membrane 3/25/2017
G. Podgorski, Biol. 1010
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Functions of Cell Membrane
The Plasma Membrane 3/25/2017 Functions of Cell Membrane Protective barrier Regulate transport in & out of cell (selectively permeable) Allow cell recognition Provide anchoring sites for filaments of cytoskeleton G. Podgorski, Biol. 1010
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Homeostasis Balanced internal condition of cells
The Plasma Membrane 3/25/2017 Homeostasis Balanced internal condition of cells Also called equilibrium Maintained by cell membrane controlling what enters & leaves the cell G. Podgorski, Biol. 1010
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Structure of the Cell Membrane
The Plasma Membrane 3/25/2017 Structure of the Cell Membrane G. Podgorski, Biol. 1010
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Cell Membrane Hydrophobic molecules pass easily; hydrophilic DO NOT
The Plasma Membrane 3/25/2017 Polar heads are hydrophilic “water loving” Nonpolar tails are hydrophobic “water fearing” Makes membrane “Selective” in what crosses Hydrophobic molecules pass easily; hydrophilic DO NOT G. Podgorski, Biol. 1010
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Types of Transport Across Cell Membranes
The Plasma Membrane 3/25/2017 Types of Transport Across Cell Membranes G. Podgorski, Biol. 1010
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2 types of Transport Does not require energy.
Active Transport Passive Transport Does not require energy. Move particles from an area of high concentration to an area of low concentration Examples: osmosis and diffusion Requires Energy Moves particles from an area of low concentration to an area of high concentration Examples:endocytosis and exocytosis
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The Plasma Membrane 3/25/2017 Diffusion Movement of particles from an area of high concentration to an area of low concentration G. Podgorski, Biol. 1010
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Diffusion through a Membrane
The Plasma Membrane 3/25/2017 Diffusion through a Membrane Cell membrane Solute moves DOWN concentration gradient (HIGH to LOW) G. Podgorski, Biol. 1010
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Facilitated Diffusion
The Plasma Membrane 3/25/2017 Facilitated Diffusion Molecules will randomly move through the pores in Channel Proteins. copyright cmassengale G. Podgorski, Biol. 1010
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Diffusion across a membrane Semipermeable membrane
The Plasma Membrane 3/25/2017 Osmosis Diffusion across a membrane Diffusion of water across a membrane Moves from HIGH water potential to LOW water potential Semipermeable membrane G. Podgorski, Biol. 1010
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Active Transport Examples
Exocytosis- moving large things out Endocytosis- Moving large things in Pinocytosis- Drinking of the cell Phagocytosis- Eating of the cell
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The Plasma Membrane 3/25/2017 Pinocytosis -Takes in dissolved molecules as a vesicle. “Cell Drinking” G. Podgorski, Biol. 1010
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Endocytosis – Phagocytosis
The Plasma Membrane 3/25/2017 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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Phagocytosis About to Occur
The Plasma Membrane Phagocytosis About to Occur 3/25/2017 G. Podgorski, Biol. 1010
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The Plasma Membrane 3/25/2017 Phagocytosis - Capture of a Yeast Cell by Membrane Extensions of an Immune System Cell G. Podgorski, Biol. 1010
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The Plasma Membrane 3/25/2017 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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Exocytosis- moving things out.
The Plasma Membrane Moving the “Big Stuff” 3/25/2017 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 and how nerve cells communicate with one another. G. Podgorski, Biol. 1010
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Isotonic Solution- concentration inside and outside are equal
The Plasma Membrane 3/25/2017 Isotonic Solution- concentration inside and outside are equal 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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The Plasma Membrane 3/25/2017 Hypotonic Solution- concentration of solution is lower than concentration of cell 10% NaCL 90% H2O CELL 20% NaCL 80% H2O What is the direction of water movement? G. Podgorski, Biol. 1010
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The Plasma Membrane 3/25/2017 Hypertonic Solution- concentration of solution is higher than concentration of cell 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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Cells in Solutions The Plasma Membrane 3/25/2017
G. Podgorski, Biol. 1010
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NO NET MOVEMENT OF H2O (equal amounts entering & leaving)
The Plasma Membrane 3/25/2017 Isotonic Solution Hypotonic Solution Hypertonic Solution NO NET MOVEMENT OF H2O (equal amounts entering & leaving) G. Podgorski, Biol. 1010
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Osmosis in Red Blood Cells
The Plasma Membrane 3/25/2017 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 3/25/2017 isotonic hypotonic hypertonic hypertonic isotonic hypotonic G. Podgorski, Biol. 1010
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Transport Across the Membrane
The Plasma Membrane Transport Across the Membrane 3/25/2017 G. Podgorski, Biol. 1010
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Facilitated diffusion
The Plasma Membrane 3/25/2017 Passive Transport 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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Active Transport Requires energy or ATP
The Plasma Membrane 3/25/2017 Active Transport Requires energy or ATP Moves materials from LOW to HIGH concentration AGAINST concentration gradient G. Podgorski, Biol. 1010
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