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Plasma membrane/cell membraneHow does it control what goes into and outof the cell????
Selectively permeable:
Allows only certain molecules to pass through
Permeable: Can pass through
BUT
Not all molecules get in the same way!
Selective Permeability
O2, CO2, and other small, nonpolar
molecules; some water molecules
glucose and other large, polar, water-soluable molecules; ions,
water molecules
Nonpolar= equal charge throughout molecule Polar= uneven charge in molecule
Active (requires NRG)
Passive (no NRG)
Types of Transport
NRG= ENERGY
• Whether passive or active transport is Whether passive or active transport is needed depends on the needed depends on the CONCENTRATION GRADIENTCONCENTRATION GRADIENT
• The concentration gradient is the The concentration gradient is the differencedifference in the concentration of a in the concentration of a substance in two different spacessubstance in two different spaces
• ConcentrationConcentration - the amount of a - the amount of a particular substance in a contained particular substance in a contained area compared with the amount of the area compared with the amount of the same substance in another areasame substance in another area
• Translation: Amount of something in a Translation: Amount of something in a space (water, salt, sugar, iron,)space (water, salt, sugar, iron,)
Passive transport:
Active transport:
No energy needed
Follows concentration gradient (high to low)
Energy needed
Against concentration gradient:
Transport within the cellTransport within the cell
Low to high
(Adenosine triphosphate)
Osmosis
Passive
Passive Transport
Diffusion
Facilitated Diffusion
Pass
ive
Tra
nspo
rt
High Concentration
Low Concentration
High Concentration Low
Concentration
DiffusionPassive Transport
H L
Movement of SUBSTANCE from area of high concentration to area of low concentration
Equilibrium reached when molecules are evenly distributed
“out”
Passive transport
Factors Affecting Diffusion Rate
• Steepness of concentration gradient– Steeper gradient, faster diffusion
• Molecular size– Smaller molecules, faster diffusion
• Temperature– Higher temperature, faster diffusion
• Charge– Charged molecules cannot diffuse (NaCl Na+ Cl-)
HighConcentration
LowConcentration
CellMembrane
Glucosemolecules
Proteinchannel
Facilitated Diffusion
Protein channel recognizes molecule and allows entry
No NRG required, following concentration gradient
Faster than diffusion
Osmosis
Diffusion of WATER across a membrane
100 ml Distilled
H20
100 ml10% Saltsolution
Which has more water?
Water will move into or out of cell following the concentration gradient of water
Osmosis
Where is there more water???
Osmosis in ANIMAL CELLS
• In Pure water • In STRONG Sugar solution
WEAK sugar/salt solution INSIDE
animal cell
Cell swells & ... Cell swells & ... LYSE LYSE (BURST) (BURST)
WEAK sugar/salt
solution INSIDE animal cell
Cell shrinksCell shrinks
Osmosis in PLANT CELLS
• In Pure water • In STRONG Sugar solution
WEAK sugar/salt solution INSIDE
potato cell
Cell swells : Cell swells : TURGIDTURGID
WEAK sugar/salt solution INSIDE
potato cell
Cell shrinks : Cell shrinks : PLASMOLYSEDPLASMOLYSED
Plasmolysis
http://www.uic.edu/classes/bios/bios100/lectf03am/plasmolysis.jpg
Plasmolysis video site
Cell Size
How does the size of a cell affect the rate of exchange of materials in and out of the cell?
The bigger the surface area of the cell membrane, the more materials can diffuse in and out of the cell.
MembraneMovements
Active
Active Transport
Pumps
Endocytosis Exyocytosis
Against concentrationgradient
Uses NRG (ATP)
Active T
ransportHigh Concentration
Low Concentration
Active TransportActive Transport
LC HC
• Span the lipid bilayer
• Interior is able to open to both sides
• Change shape when they interact with solute
• Move water-soluble substances across a membrane
Transport Proteins
Pumps
MembraneMovements
Endocytosis and Exocytosis
plasma membrane
cytoplasm
cytoplasm
Exocytosis
Endocytosis
Exocytosis
Pinocytosis (cell drinking)
Phagocytosis (cell eating)
Process where cell membrane “pinches in” drawing molecules into the cell forming a pinocytic vesicle
Process where pseudopods of a cell flow around matter and engulf it forming a food vacuole
Phagocytosis (Movie)
What about single celled organisms that live in freshwater (amoeba/paramecium)? Why don’t they burst?
Active Transport: going against the gradient
Passive Transport:Passive Transport:• Mvmt of materials Mvmt of materials
Without use of energy.Without use of energy.
• With Concentration With Concentration GradientGradient
• HCHCLCLC
• Examples:Examples:– DiffusionDiffusion– OsmosisOsmosis– Facilitated DiffusionFacilitated Diffusion
Active TransportActive Transport• Mvmt of materials Mvmt of materials using using
energy.energy.
• Against Concentration Against Concentration gradientgradient
• LCLCHCHC
• Examples:Examples:– EndocytosisEndocytosis
• PhagocytosisPhagocytosis• PinocytosisPinocytosis
– ExocytosisExocytosis
Video 4
• video segment.
Video 4
Active Transport
Animations
Dialysis Bag Experiment• http://ccollege.hccs.cc.tx.us/instru/Biology/AllStud
yPages/Diffusion_Osmosis/Baggif.swf
Elodea Cell• http://ccollege.hccs.cc.tx.us/instru/Biology/AllStud
yPages/Diffusion_Osmosis/Elodeagif.swf
Osmosis• http://ull.chemistry.uakron.edu/genobc/animation
s/osmosis.mov