1 Gateway to the Cell Gateway to the Cell
Mar 26, 2015
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Gateway to the CellGateway to the Cell
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Protective barrierProtective barrier
Regulate transport in & out of Regulate transport in & out of cell cell (selectively permeable)(selectively permeable)
Allow cell recognitionAllow cell recognition
Provide anchoring sites for Provide anchoring sites for filaments filaments of cytoskeletonof cytoskeleton
Balanced internal condition of cells
Also called equilibrium Maintained by cell
membrane controlling what enters & leaves the cell
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Polar heads are hydrophilichydrophilic “water loving”
Nonpolar tails are hydrophobichydrophobic “water fearing”Makes membrane “Selective” in what crosses
Hydrophobic molecules pass easily; hydrophilic DO NOT
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PASSIVE TRANSPORTACTIVE 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
Movement of particles from an area of high concentration to an area of low concentration
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Cell membrane
Solute moves DOWN concentration gradient (HIGH to LOW)
copyright cmassengale 10
Molecules will randomly move Molecules will randomly move through the through the porespores in in Channel Channel ProteinsProteins..
Diffusion of Diffusion of waterwater across a across a membranemembrane
Moves from Moves from HIGH water HIGH water potential to potential to LOW water LOW water potentialpotential
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Diffusion across a membrane
Semipermeable
membrane
Exocytosis- moving large things out
Endocytosis- Moving large things in
Pinocytosis- Drinking of the cell Phagocytosis- Eating of the cell
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PinocytosisPinocytosis
--Takes in dissolved Takes in dissolved molecules as a vesiclemolecules as a vesicle.
“Cell Drinking”
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Endocytosis – Phagocytosis Endocytosis – Phagocytosis
Used to Used to engulf large particlesengulf large particles such such as food, as food, bacteriabacteria, etc. into vesicles, etc. into vesicles
Called Called “Cell Eating”“Cell Eating”
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Phagocytosis About to OccurPhagocytosis About to Occur
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PhagocytoPhagocytosissis - Capture of a Yeast Cell by Membrane Extensions of an Immune System Cell
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ExocytosisExocytosis The opposite of endocytosis is exocytosis. The opposite of endocytosis is exocytosis. Large moleculesLarge molecules that are manufactured in that are manufactured in
the cell are the cell are releasedreleased through the cell through the cell membranemembrane..
Inside Cell Cell environment
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Moving the “Big Stuff”Moving the “Big Stuff”
Molecules are Molecules are moved outmoved out of the cell by of the cell by vesiclesvesicles that that fusefuse with the plasma membrane. with the plasma membrane.
ExocytosiExocytosiss-
moving things out.
This is how many This is how many hormoneshormones are secreted and how are secreted and how nerve cellsnerve cells communicate with one another communicate with one another.
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CELLCELL
10% NaCL90% H2O
10% NaCL
90% H2O
What is the direction of water movement?The cell is at _______________.equilibrium
ENVIRONMENTENVIRONMENT
NO NET NO NET MOVEMENMOVEMENTT
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CELLCELL
10% NaCL90% H2O
20% NaCL
80% H2O
What is the direction of water movement?
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CELLCELL
15% NaCL85% H2O
5% NaCL95% H2O
What is the direction of water movement?
ENVIRONMENTENVIRONMENT
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Isotonic Solution
NO NET MOVEMENT OF
H2O (equal amounts entering
& leaving)
Hypotonic Solution
Hypertonic Solution
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IsotonicIsotonic Hypotonic
Hypertonic
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hypotonic hypertonic isotonic
hypertonic isotonic hypotonic
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Transport Across the MembraneTransport Across the Membrane
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Passive Passive TransportTransport
Facilitated diffusion
Doesn’t require energy
Uses transport proteins to move high to low concentrationExamples: Examples: GlucoseGlucose or or amino acidsamino acids moving moving from blood into a from blood into a cell.cell.
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Active TransportActive Transport
Requires energy or ATP
Moves materials from LOW to HIGH concentration
AGAINST concentration gradient