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?