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49 Cards in this Set
- Front
- Back
Passive Transport
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when substances cross the cell membrane without any input of energy by the cell
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Name the 4 types of Passive diffusion
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1. Diffusion 2. Osmosis 3. Facilitated diffusion 4. Ion channel
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Diffusion
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movement of molecules from higher concentration to lower concentration. Diffusion is driven by the molecule’s kinetic energy
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simple diffusion
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Diffusion across a membrane is called simple diffusion. Simple diffusion across membrane depends on the size and type of molecule and chemical nature of the membrane.
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What 3 things influence simple diffusion?
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1. size of molecule
2.type of molecule 3.chemical nature of the membrane |
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Concentration Gradient
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the difference in concentration of molecules across a distance. Molecules move down their concentration gradient, i.e.- from high to low concentration
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Molecules move____their concentration gradient. They move from ______ to _____ concentration
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down, high, low
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Equilibrium
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When the concentration of moleculesare equal through out the space they occupy. When in equilibrium the molecules are still randomly moving in many directions, with the different directions balancing each other.
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Osmosis
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passive transport of water across cell membranes, diffusion of water across cell membrane from an area of higher concentration to an area of lower concentration. Osmosis does not require cells to expend energy.
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A solution is composed of a ___ dissolved in a ____. In cells, solutes are ___ &___ compounds, and the solvent is____.
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solute, solvent
organic and inorganic water |
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Water diffuses from ____ to ____ solutions.
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hypotonic
hypertonic |
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Hypotonic
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concentration of solute molecules is lower than concentration on other side; water will move to side with higher concentrate of solute
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Hypertonic
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concentration of solute molecules is higher than concentration on other side; water will move from the hypotonic to hypertonic side
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Isotonic
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when concentrations of solutes are equal on both sides, water will diffuse into and out of a cell at equal rates, so that there is no net movement
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Contractile Vacuole
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organelles that remove excess water and contract to pump water out of the cell. This is not passive, as it requires cell to expend energy. (example the unicellular fresh water organism, paramecium)
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Turgor Pressure
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pressure that water molecules exert against the cell wall
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Plasmolysis
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process by which plant cells wilt, because the are in a hypertonic environment, and water leaves the cell. This causes the cell to shrink away from the cell wall, and turgor pressure is lost.
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Cytolysis
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the bursting of cells, because of hypotonic environment water diffuses into the cell, causing it to swell and eventually burst. (ex: red blood cell in hypotonic environment)
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Facilitated Diffusion
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a form of passive transport, which uses carrier proteins in the cell membrane to assist movement of molecules, that maybe too large for the pores in the membrane, or non soluble in lipids of the membranes
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Carrier Protein
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specific proteins in cell membrane that allow facilitated diffusion to occur EX: Glucose is too large to cross cell membranes and only moves into cells because of carrier proteins
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What are carrier proteins specific to?
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A single molecule
(different carrier proteins exisit for glucose, and amino acids, etc.) |
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Ion Channel
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another form of passive transport that uses a membrane protein channel to allow movement of an ion across the cell membrane. ( example of an ion: Na , K , Ca , Cl )
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Name 3 stimuli that gated ion channels respond to
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1.stretching
2. electrical signals 3.presence of certain chemicals in the cytosol |
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Active Transport
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Movement of molecules up the concentration gradient, i.e. from low to high concentration. Active transport requires energy (ATP) from the cell.
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Cell Membrane pump
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Carrier protein used in active transport across a membrane
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3 forms of active transport
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1. Cell membrane pump such as the sodium-potassium pump 2. Endocytosis 3. Exocytosis
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Sodium-Potassium Pump
NA / K |
A carrier protein pump that transports Na , and K , ions up their concentration gradient, a form of active transport.
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Where does the NA/K pump get it's energy?
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The cycle uses the P, phosphorus, from ATP-converting it into ADP
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What and how much does the NA/K pump move across the cell membrane?
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It moves 3 NA molecules out of the cell, and 2 K molecules into the cell
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What does the NA/K pump's action result in?
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It results in positive charge outside the cell and relative negative charge inside the cell, a current gradient.
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Give an example of use of the NA/K pump current gradient
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The current gradient is important for the conduction of electrical impulses along nerve cells.
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Endocytosis
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a form of active transport by which cells ingest external fluid, macromolecules, including other cells, into a portion of the cell’s membrane that folds into itself, making a pouch that pinches off becoming a vesicle.
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vesicle
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a membrane bound organelle
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What are the 2 main forms of endocytosis?
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pinocytosis and phagocytosis.
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pinocytosis
(to drink) |
a form of endocytosis that involves the transport of solutes or fluids into the cell
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phagocytosis
(to eat) |
a form of endocytosis that involves the transport of large particles or whole cells into the cell
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Phagocyte
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Cells in a body that eat bacteria and viruses that invade the body. After eating the bad guys, lysosomes will fuse with the vesicle containing the bacteria or virus so that the lysosomal enzymes can kill the bacteria or virus.
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Give example of a phagocyte
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human white blood cells that fight infections from bacteria and viruses
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Exocytosis
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Process by which a substance is released from a cell (the reverse of endocytosis).
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ecto-
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outer, outside
ex:ectoderm (skin) |
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endo-
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inner, inside
ex: endoplasm=cytoplasm or fluid inside the cell |
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epi-
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upon, over
ex:epiphyte- plant growing upon another plant |
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hyper-
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over, above
ex: hypertension (high blood pressure) |
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hypo-
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under, below
ex: hypothalamus- part of the brain below the thalmus |
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-ic
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of or pertaining to
ex: hpodermic- pertaining to under the skin |
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-oma
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swelling
ex: tumor, hematoma (bruise) |
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-some
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Body
ex: chromosome- structure containing DNA |
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syn-
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with
ex: synapse- junction of a neuron with another cell |
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trans-
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Across ex: transformation- the transfer of genetic material from one organism to another
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