The Plasma Membrane The Plasma Membrane - Gateway to the Cell.
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Transcript of The Plasma Membrane The Plasma Membrane - Gateway to the Cell.
The Plasma MembraneThe Plasma Membrane -
Gateway to the CellGateway to the Cell
Photograph of a Cell Photograph of a Cell MembraneMembrane
Types of Transport Types of Transport Across Cell MembranesAcross Cell Membranes
Simple DiffusionSimple Diffusion
• Requires NONO energy
• Molecules move from area of HIGH to LOWHIGH to LOW concentration
DIFFUSIONDIFFUSION
Diffusion is a PASSIVEPASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY
Diffusion of LiquidsDiffusion of Liquids
Diffusion through a MembraneDiffusion through a Membrane
Cell membrane
Solute moves DOWN concentration gradient (HIGH to LOW)
OsmosisOsmosis• Diffusion of waterDiffusion of water
across a membraneacross a membrane• Moves from Moves from HIGH HIGH
water potentialwater potential (low (low solute) to solute) to LOW LOW water potentialwater potential (high (high solute)solute)
Diffusion across a membrane
Semipermeable
membrane
Diffusion of HDiffusion of H22O Across A O Across A
MembraneMembrane
High H2O potentialLow solute concentration
Low H2O potentialHigh solute concentration
Cell in Isotonic SolutionCell in Isotonic Solution
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
Cell in Hypotonic SolutionCell in Hypotonic Solution
CELLCELL
10% NaCL90% H2O
20% NaCL
80% H2O
What is the direction of water movement?
Cell in Hypertonic SolutionCell in Hypertonic Solution
CELLCELL
15% NaCL85% H2O
5% NaCL95% H2O
What is the direction of water movement?
ENVIRONMENTENVIRONMENT
Cells in SolutionsCells in Solutions
Isotonic Solution
NO NET MOVEMENT OF
H2O (equal amounts entering
& leaving)
Hypotonic Solution
CYTOLYSIS
Hypertonic Solution
PLASMOLYSIS
Cytolysis & PlasmolysisCytolysis & Plasmolysis
Cytolysis Plasmolysis
Osmosis in Red Blood CellsOsmosis in Red Blood Cells
IsotonicIsotonic Hypotonic
Hypertonic
hypotonic hypertonic isotonic
hypertonic isotonic hypotonic
Three Forms of Transport Across the MembraneThree Forms of Transport Across the Membrane
Passive Passive TransportTransport
Simple DiffusionSimple Diffusion
Doesn’tDoesn’t require require energyenergy
Moves Moves high to lowhigh to low concentrationconcentration Example: Example: OxygenOxygen or or waterwater diffusing into a diffusing into a cell and cell and carbon carbon dioxidedioxide diffusing out diffusing out.
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.
Proteins Are Critical to Proteins Are Critical to Membrane FunctionMembrane Function
Active TransportActive Transport
Requires energy or ATP
Moves materials from LOW to HIGH concentration
AGAINST concentration gradient
Active transportActive transport
Examples: Pumping Na+ (sodium ions) out and K+ (potassium ions) in against strong concentration gradients.
Called Na+-K+ Pump
Sodium-Potassium Sodium-Potassium PumpPump
3 Na+ pumped in for every 2 K+ pumped out; creates a membrane
potential
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.
ExocytosExocytosisis-
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.
ExocytosisExocytosisExocytic Exocytic vesicle vesicle immediately immediately after fusion after fusion with plasma with plasma membrane.membrane.
Moving the “Big Moving the “Big Stuff”Stuff”Large molecules move materials into the Large molecules move materials into the
cell by one of cell by one of three forms of endocytosisthree forms of endocytosis.
PinocytosisPinocytosis
Most Most commoncommon form of endocytosis form of endocytosis. Takes in Takes in dissolveddissolved molecules as a molecules as a vesiclevesicle.
PinocytosisPinocytosis
• Cell forms an Cell forms an invaginationinvagination
• Materials Materials dissolve dissolve in waterin water to be to be brought into cellbrought into cell
• Called Called “Cell “Cell Drinking”Drinking”
Example of Example of PinocytosisPinocytosispinocytic vesicles forming mature transport vesicle
Transport across a capillary cell (blue).
Receptor-Mediated EndocytosisReceptor-Mediated Endocytosis
Some Some integral proteinsintegral proteins have have receptorsreceptors on their surface to on their surface to recognize & take in recognize & take in hormones, hormones, cholesterolcholesterol, etc., etc.
Receptor-Mediated EndocytosisReceptor-Mediated Endocytosis
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”
Phagocytosis About to OccurPhagocytosis About to Occur
PhagocytoPhagocytosissis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue)
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
OSMOSIS
http://www.biology4kids.com/files/cell_main.html
Diffusion
http://lhs.lps.org/staff/sputnam/Biology/U3Cell/diffusion_1.png
See a video clip aboutDIFFUSION-7A
Molecules move _______“where there’s _______” ____“where there’s _______”
Animatioin from: http://www.biologycorner.com/resources/diffusion-animated.gif
FROMto
A LOTNOT
DIFFUSION across a space
Happens anytime there is a __________ in concentration in one place compared to another
= ________________________
DIFFERENCE
Concentration gradient
DIFFUSION across a SPACE• Molecules move automatically
_______ the concentration gradient _______ an area of _______ concentration ____ an area of ________ concentration
• EXAMPLES
HigherLower
Blue dye in beaker demo,Someone making popcorn/grilling outStrong perfume,Bad smell in room
http://www.swapmeetdave.com/Humor/Farts.htmhttp://leighhouse.typepad.com/blog/images/kool_aid.jpg
DOWNfrom
to
DIFFUSION across a space
Diffusion continues until the concentration is ________________ in space
= ________________________Equilibrium
http://lhs.lps.org/staff/sputnam/Biology/U3Cell/diffusion_1.png
equal everywhere
Molecules need to move across
membranes in cells
Image modiified from: http://www.accessexcellence.org/AB/GG/importProt.html
Diffusion can happen ________ a _____________ in a cell, too
…as long as membrane will let the molecule _________________
acrossmembrane
pass through
SELECTIVELY
PERMEABLE(Semi-
permeable)
http://life.nthu.edu.tw/~d857401/advance.html
See a movie
Video from: http://www.southtexascollege.edu/tdehne/BC_ShockwaveAnimations/08SWF-MembraneStructureAndFunct/08-02-MembraneStructure.swf
DIFFUSION automatically moves oxygen from HIGHER concentration (in lungs) to a LOWER concentration (in blood)
http://www.le.ac.uk/pa/teach/va/anatomy/case2/2_2.html
CELL EXAMPLE:
CO2 automatically movesfrom where there is aHIGHER concentration (in blood) to where thereis a lower concentration (in lungs)
BUT….What if a cell needs to move _____ or ______ molecules?
http://www.d.umn.edu/~sdowning/Membranes/membraneImages/jpegimages/diffusionmedium.jpg
LARGE POLAR
What if cell needs to move a molecule _________ the CONCENTRATION GRADIENT?_______________
Cell example:Want to put MORE glucoseinto mitochondria when there
isalready glucose in there
(LOWER HIGHER)
Image from: http://www.biologyclass.net/mitochondria.jpg
AGAINST
What if cell needs to move molecules really
_______? (can’t wait for it to diffuse)
Cell example:Movement of Na + & K+ ions required to send nerve signals
http://www.steve.gb.com/images/science/neuron.png
FAST
We need a ____ to ____ molecules across cell
membranes that _______ across by
___________
WAY HELP
can’t go
themselves
Kidspiration by: Riedell
Kinds of ________ Transport
•Diffusion
•Osmosis•Facilitated Diffusion
__________________________________
___________________________________
___________________________________
PASSIVE
DIFFUSION across a membrane
Happens anytime there is a __________ in _____________ on one side of the membrane compared to the other
DIFFERENCE
Molecules that move by diffusion across membranes in cells:____________________________
OXYGEN
CARBON DIOXIDEhttp://www.lionden.com/cell_animations.htm
See diffusionanimation
concentration
OSMOSIS= SPECIAL KIND OF DIFFUSION
IMAGE by RIEDELL
See osmosis animation
____________
__________
OSMOSIS
DIFFUSION
Movement of molecules across a_________________ membranefrom ______ concentration to _____Semi-permeable
Higher lower
See a video about Passive transport 7-C
Facilitated Diffusion_______ proteins help diffusion go
fasterCarrier
FACILITATED DIFFUSION
• No energy required = __________________
• Moves _________ concentration gradient from ________________________
• _____________________ grab molecule, change shape, and flip to other side (Like a revolving door)
• Molecules that move this way in cells:_______________________
PASSIVE
Membrane proteins
GLUCOSE
HIGHER to LOWERDOWN
Facilitated DiffusionAnimation from: http://bio.winona.edu/berg/ANIMTNS/facdifan.gif
Kidspiration by: Riedell
Kinds of ________Transport
•Sodium-Potassium Pump•Endocytosis•Exocytosis
________________________________________
___________________________________
____________________________________
ACTIVE
See a video clip aboutNa+-K+ pump -7D
Sodium (Na+)- Potassium (K+) Pump
Animation from: http://www.lionden.com/cell_animations.htm
See a movie about Na+ - K+ pump
Sodium-Potassium pump
• ___________ transport (requires energy from ______)
• Special just for Na+ and K + ions
• Uses integral ___________________ to move molecules
• Examples in nerve cells: Na+ is pumped out of cells at same time K + is taken into cells
ACTIVE
Carrier Proteins
ATP
See a video clip aboutEndo/exocytosis -7E
ENDOCYTOSISTakes substances into cell
• _____________transport (requires __________ from ______)
• Uses small membrane sacs called ______________ to carry substances
ACTIVE
VESICLES
http://www.sirinet.net/~jgjohnso/cell.html
energy ATP
2 KINDS of ENDOCYTOSIS
Takes substances into cellIf taking in:fluid or small molecules =_________________large particles or whole cells =______________
• Examples in cells:– one celled organisms eat this way– white blood cells get rid of bacteria this
way
PINOCYTOSIS
PHAGOCYTOSIS
PinocytosisPinocytosis
• Called Called “Cell “Cell Drinking”Drinking”
ENDOCYTOSISAnimation from: http://academic.brooklyn.cuny.edu/biology/bio4fv/page/cell-movement.html
http://www.accs.net/users/kriel/chapter%20nine/
PHAGOCYTOSIS
___________ destroying _______White blood cell germs
CalledCalled “Cell “Cell Eating”Eating”
EXOCYTOSISSubstances released outside
of cell
• __________ transport (requires __________)
• Substances move in____________
• Examples in cells:– _________ release packaged proteins
this way
ACTIVE
VESICLES
energy
GOLGI
Exocytosis
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBooktransp.html
GOLGI BODIES USE EXOCYTOSIS
Animation from: http://www.franklincollege.edu/bioweb/A&Pfiles/week04.html
See a Golgi movie
Video: http://www.southtexascollege.edu/tdehne/BC_ShockwaveAnimations/07SWF-TourOfTheCell/07-16-EndomembraneSystem.swf
Endocytosis & Exocytosis
Watch a video clip about endo/exocytosis
Watch a video clip about endo/exocytosis
Choose Screen/Switch programs to view
Videos from: http://www.pleasanton.k12.ca.us/avhsweb/thiel/apbio/notes/chp8/exocytosis_endocytosis.movhttp://trc.ucdavis.edu/biosci10v/bis10v/week2/endocytosis.mov
INSULIN being released by pancreas cells using
exocytosis
http://fig.cox.miami.edu/~cmallery/255/255ion/fig14x26.jpg
What if there is a difference in concentration but solute
molecules can’t move across a membrane?
WATER will move until concentrationreaches equilibrium
VOCAB_____________ = substance that is
dissolved in a solvent to make a solution
_____________ = substance in which a solute is dissolved
SOLUTE
EX:Koolaid powder = soluteWater = solventKoolaid drink = solution
SOLVENT
http://www.makash.ac.il/h_school/hst/hstsb/chem/luach/dissolve.jpg
__________________ = mass of a solute in a given volume of solution
CONCENTRATION
The _______ molecules there are in a given volume the ____________the concentration
Images by Riedell
MOREGREATER
See a video clip aboutOSMOSIS -7B
See an animation Osmosis1
http://faculty.etsu.edu/currie/images/osmosis1.jpg
Animation: http://www.ouhscphysio.org/humanphys/animations/osmosis1.swf
OSMOSIS
HYPERTONIC: Concentration outside cell is ____________________ inside cell
More water leaves cell than enters so cell ____________
GREATER THAN
shrinks
See an animationOSMOSIS 4
Animation from: http://www.ouhscphysio.org/humanphys/animations/osmosis4.swf
Cell in Hypertonic SolutionCell in Hypertonic Solution
CELLCELL
15% NaCL85% H2O
5% NaCL95% H2O
What is the direction of water movement?
ENVIRONMENTENVIRONMENT
OSMOSIS
HYPOTONIC: Concentration outside cell is ________________ inside the cell
More water enters than leaves cell so cellwill ___________________
LESS THAN
Swell and possibly burst
See an animationOsmosis3
Animation from: http://www.ouhscphysio.org/humanphys/animations/osmosis3.swf
Cell in Hypotonic SolutionCell in Hypotonic Solution
CELLCELL
10% NaCL90% H2O
20% NaCL
80% H2O
What is the direction of water movement?
OSMOSIS
ISOTONIC: Concentration outside cell
__________concentration inside cell Water entering = water leaving
so cell _____________________
EQUALS
STAYS THE SAME SIZE
Cell in Isotonic SolutionCell in Isotonic Solution
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
Isotonic Solution
NO NET MOVEMENT OF
H2O (equal amounts entering
& leaving)
Hypotonic Solution
Cell Swells & may burst
Hypertonic Solution
Cell shrivels up
Animal cells
http://www.stchs.org/science/courses/sbioa/metenergy/bloodcells.gif
Osmosis in Red Blood CellsOsmosis in Red Blood Cells
IsotonicIsotonic Hypotonic
Hypertonic
Plant cellshttp://www.stchs.org/science/courses/sbioa/metenergy/aplantturgor.gif
CELL WALL_____ keepsPlant cells from bursting
VACUOLES store WATER
http://www.biology4kids.com/files/cell_vacuole.html
_____________________________ =Pressure exerted by water during osmosis
OSMOTIC PRESSURE
SO WHAT?
Sitting in the bathtub causes your fingers and toes to wrinkle up when water ________ your skin cells by osmosis
Bath water is ________________compared to youhypotonic
enters
Grocery stores spray water on their veggies to “plump them up”
http://www.painetworks.com/photos/gt/gt0461.JPG
SO WHAT?