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Structure (Plasma Membrane)
Cell Membrane (Plasma Membrane) Structure A lipid bilayer(2 layers of lipids) with a variety of proteins
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Proteins Lipid molecule
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Identify the lipid molecules. Identify the protein molecules.
Go to Membrane Diagram Identify the lipid molecules. Identify the protein molecules. What is a ‘lipid bilayer’?
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-To be Selective Permeable: =
Cell Membrane (Plasma Membrane) Function -Helps maintain Homeostasis: = maintain a stable internal environment -To be Selective Permeable: = control what passes in or out of the cell
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Cell Membrane What the lipids do… -Act as a lining, separates the chemicals of the cytoplasm from the surroundings
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All to move molecules in & out of the cell!
Cell Membrane (Plasma Membrane) What the proteins do… Form a. open channels b. gated channels c. active transport pathways, All to move molecules in & out of the cell!
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Ex. 1 of channel proteins. Open channels
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Ex. 2 of channel proteins. Gated channel
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-Receptors that change cellular activity.
Cell Membrane (Plasma Membrane) Protein Function #2 -Receptors that change cellular activity.
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Signal molecule Receptor protein
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Change cellular activity
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Protein Function #3 (Plasma Membrane)
Cell Membrane (Plasma Membrane) Protein Function #3 -Create a molecular mark (signature) that identifies that specific, individual cell.
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Recognition protein
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LOOK!
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Types of particle that might cross membranes.
Tiny molecules, like… Water Oxygen & Carbon dioxide
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Types of particle that might cross membranes.
Small molecules, like… Glucose, amino acids, fatty acids and glycerol
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Carbon Dioxide Oxygen Water Amino acid Glycerol Glucose Fatty Acid
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Yet more types of particles that might cross cell membranes!
Yes, even large molecules, such as… Polysaccharides Lipids & proteins!
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Lipid soluble molecules
Fats, Fatty acids
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Charged particles ions Na+, K+, Cl+
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Such as… small organisms and Organic debris
Even Large Particles may sometimes cross the selectively permeable cell membrane! Such as… small organisms and Organic debris
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Diffusion Movement of particles from an area of high concentration to an area of lower concentration.
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Diffusion requires a Concentration gradient
When the concentration of particles is not the same throughout a mixture.
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Concentration Gradient
There is a region of high concentration and a region of low concentration.
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Go to page 7 in the note packet and learn about the use of square brackets.
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Do the activity The Tea Cup & The Swimming Pool on page 8.
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When the concentration of particles is the same throughout a mixture.
Equilibrium When the concentration of particles is the same throughout a mixture.
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Equilibrium There is no region of high, nor a region of low concentration of particles.
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All particle continue to move.
Equilibrium All particle continue to move.
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Diffusion Concentration gradient Equilibrium
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The Movement of Materials Across Membranes
TRANSPORT The Movement of Materials Across Membranes
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Materials move down the concentration gradient and across a membrane.
Passive Transport Materials move down the concentration gradient and across a membrane.
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What determines if a particle can go through a channel?
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Dialysis Tubing
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The passive transport of water across a membrane.
Osmosis The passive transport of water across a membrane.
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Thistle Tube Demo
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thistle tube molasses water Selectively permeable membrane
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Active Transport Particles move Across a SPM.
Against the concentration gradient. The cells must spend energy.
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(from an area of _____ concentration to an area of ___ concentration)
Active transport allows particles to move against the concentration gradient. (from an area of _____ concentration to an area of ___ concentration) LOW HIGH
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An example of Active Transport:
All animal cells have a Sodium Potassium pump that pumps sodium (Na+) to the outside of cells and potassium (K+) to the inside of cells.
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This ‘pump’ allows nerve cells to carry electrical messages through the body!
Nerve cell
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The Cell Membrane of a nerve cell
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Endocytosis Particles move INTO the cell by folding a portion of the membrane around a particle, resulting in a vesicle.
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Pinocytosis - drinking
There are two types of Endocytosis: Phagocytosis - eating Food particles Pinocytosis - drinking Dissolved materials
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Pinocytosis The solute particles are too small to see but too big to pass through the membrane.
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Exocytosis Particles move OUT OF a cell by fusing vesicles with the cell membrane.
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Maintaining water balance in Protists
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Facilitated Transport
(Facilitated Diffusion) -Diffusion using protein channels
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Transport protein
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Gated channel
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The End
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