Unit 4: The Cell & Its Environment
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Transcript of Unit 4: The Cell & Its Environment
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Unit 4: The Cell & Its EnvironmentCh. 2:1 (pg. 31) Cell Theory
Ch. 2:3 (pgs. 38-40) Special Cell Processes (Diffusion & Osmosis)
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Cells• Who first
observed cells?
• What was he looking at?
• Did he see live cells?–No, just cell
walls.
Robert Hooke
cork
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Further Discoveries Lead to the Cell Theory1. All organisms are made of one or more cells.
(Schleiden & Schwann)
2. The cell is the basic unit of structure and function in organisms. (Schleiden & Schwann)
3. Cells are produced from other cells (Virchow)
Cell Theory Rap
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Properties of the Plasma Membrane• What are the functions (jobs)
of the cell membrane?1. Boundary between cell & its
environment2. “Gatekeeper”
• Lets certain materials in/out (“selectively permeable”)
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A Model of the Plasma Membrane• In general, what does the plasma
(cell) membrane look like?–phospholipid bilayer
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• What does the plasma (cell) membrane look like in more detail?–“Fluid Mosaic Model”
• Molecules (like proteins) embedded in phospholipid bilayer & in constant motion
A Model of the Plasma Membrane
Membrane Movement Animation
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• What is passive transport?– Does passive transport require energy?
• Why/why not?– Ex. of passive transport?
Movement of Materials Across the Cell Membrane:
Passive Transport
Concentration gradient = differences in concentration
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• Ex. Diffusion–How do
molecules of solute move?• Do they ever
completely stop?
Movement of Materials Across the Cell Membrane: Passive Transport
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• What is the special name for the diffusion of water?– osmosis
Movement of Materials Across the Cell Membrane: Passive Transport
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• What is an isotonic solution?–concentration of
solutes (& water) same on both sides of the membrane
• Which way would water move?
Effects of Water Concentrations on Cells
How osmosis works animation
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• What is a hypotonic solution?–lower concentration
of solutes outside cell• higher concentration
of water outside cell• Which way would
water move?
Effects of Water Concentrations on Cells
How osmosis works animation
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• What is a hypertonic solution?–higher concentration
of solutes outside cell• lower concentration of
water outside cell• Which way would
water move?
Effects of Water Concentrations on Cells
How osmosis works animation
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plasmolysis
cytolysis
What adaptation prevents the plant cell from bursting?
What happens to cells in different types of solutions?
Effects of Water Concentrations on Cells: Cytolysis & Plasmolysis
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Which cells were in salt water?How can you tell?
Elodea in salt water
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• Even though they’re going w/ the concentration gradient (high low) some substances:– can not dissolve in lipid bilayer– are too large to squeeze through
Membrane FunctionPassive Transport: Facilitated Diffusion
carrier
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• So how can these materials permeate the membrane???–Facilitated diffusion
• With the help of:–Channel proteins (pores)–Carrier proteins–Gate proteins
–Does facilitated diffusion require energy? Why/why not?• No, b/c going from high low
Membrane FunctionPassive Transport: Facilitated Diffusion
carrier
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Channel & Gate Protein Animations
carrier (transport) protein
channel protein (pores)
Gate opens & ions can pass through
Signal molecule combines w/ gate
Signal molecule not combined w/ gate (gate closed)
Once ions pass through, signal molecules unbind & gate closes
gat e protein
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• What is active transport?– Does active transport
require energy?• Why/why not?
– Ex. of active transport?
Movement of Materials Across the Cell Membrane: Active Transport
Concentration gradient = differences in concentration
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• How can materials be moved against the concentration gradient (low high)?– transport proteins (pumps) that
use energy (ATP)
Movement of Materials Across the Cell Membrane: Active Transport
Protein/Transport Pumps Animation Active Transport Animation
Passive & Active Transport Animation
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• Not all materials can pass through membrane…– So, how do they get into/out of the cell?
• Membrane encloses the material pinches off releases the material on the other side– endocytosis– exocytosis
Exocytosis & Endocytosis Animation 1 Endocytosis & Exocytosis Animations 2
Active Transport:Endocytosis & Exocytosis
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• Which way do substances move during endocytosis?– What are 2 types of endocytosis?
• phagocytosis• pinocytosis
– What types of materials are moved by phagocytosis & pinocytosis?
– Do they require energy?
Exocytosis & Endocytosis Animation 1
Endocytosis & Exocytosis Animations 2
Liquid droplets
Active Transport:Endocytosis & Exocytosis
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• Which way do substances move during exocytosis?– What types of materials
are moved by exocytosis?• Does exocytosis
require energy?
Exocytosis & Endocytosis Animation 1
Endocytosis & Exocytosis Animations 2Active Transport:
Endocytosis & Exocytosis
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The Cell Wall• What is the cell wall?• Where is it located in the cell?• What is it made of?• What type of organisms have cell walls?• What does the cell wall do for the cell?• Does it affect the cell’s permeability?