The Plasma Membrane - Gateway to the Cell

Photograph of a Cell Membrane

Types of Transport Across Cell Membranes

Simple Diffusion Requires NO energy Molecules move from area of HIGH to LOW concentration

DIFFUSION Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY

Diffusion of Liquids

Diffusion through a Membrane Cell membrane Solute moves DOWN concentration gradient (HIGH to LOW)

Diffusion across a membrane Semipermeable membrane Osmosis Diffusion across a membrane Diffusion of water across a membrane Moves from HIGH water potential (low solute) to LOW water potential (high solute) Semipermeable membrane

Diffusion of H2O Across A Membrane High H2O potential Low solute concentration Low H2O potential High solute concentration

Cell in Isotonic Solution 10% NaCL 90% H2O ENVIRONMENT CELL NO NET MOVEMENT 10% NaCL 90% H2O What is the direction of water movement? equilibrium The cell is at _______________.

Cell in Hypotonic Solution 10% NaCL 90% H2O CELL 20% NaCL 80% H2O What is the direction of water movement?

Cell in Hypertonic Solution 15% NaCL 85% H2O ENVIRONMENT CELL 5% NaCL 95% H2O What is the direction of water movement?

Cells in Solutions

NO NET MOVEMENT OF H2O (equal amounts entering & leaving) Isotonic Solution Hypotonic Solution Hypertonic Solution NO NET MOVEMENT OF H2O (equal amounts entering & leaving) CYTOLYSIS PLASMOLYSIS

Cytolysis & Plasmolysis

Osmosis in Red Blood Cells Isotonic Hypertonic Hypotonic

isotonic hypotonic hypertonic hypertonic isotonic hypotonic

Three Forms of Transport Across the Membrane

Passive Transport Simple Diffusion Doesn’t require energy Moves high to low concentration Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out.

Facilitated diffusion Passive Transport Facilitated diffusion Doesn’t require energy Uses transport proteins to move high to low concentration Examples: Glucose or amino acids moving from blood into a cell.

Proteins Are Critical to Membrane Function

Active Transport Requires energy or ATP Moves materials from LOW to HIGH concentration AGAINST concentration gradient

Active transport Examples: Pumping Na+ (sodium ions) out and K+ (potassium ions) in against strong concentration gradients. Called Na+-K+ Pump

Sodium-Potassium Pump 3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential

Exocytosis- moving things out. Moving the “Big Stuff” Exocytosis- moving things out. Molecules are moved out of the cell by vesicles that fuse with the plasma membrane. This is how many hormones are secreted and how nerve cells communicate with one another.

Exocytosis Exocytic vesicle immediately after fusion with plasma membrane.

Moving the “Big Stuff” Large molecules move materials into the cell by one of three forms of endocytosis.

Pinocytosis Most common form of endocytosis. Takes in dissolved molecules as a vesicle.

Pinocytosis Cell forms an invagination Materials dissolve in water to be brought into cell Called “Cell Drinking”

Example of Pinocytosis mature transport vesicle pinocytic vesicles forming Transport across a capillary cell (blue).

Receptor-Mediated Endocytosis Some integral proteins have receptors on their surface to recognize & take in hormones, cholesterol, etc.

Receptor-Mediated Endocytosis

Endocytosis – Phagocytosis Used to engulf large particles such as food, bacteria, etc. into vesicles Called “Cell Eating”

Phagocytosis About to Occur

Phagocytosis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue)

Exocytosis The opposite of endocytosis is exocytosis Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. 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 about DIFFUSION-7A

FROM A LOT to NOT Molecules move _______“where there’s _______” Animatioin from: http://www.biologycorner.com/resources/diffusion-animated.gif Molecules move _______“where there’s _______” ____“where there’s _______” FROM A LOT to NOT

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 DOWN from Higher to Lower Blue dye in beaker demo, Someone making popcorn/grilling out Strong perfume, Bad smell in room http://leighhouse.typepad.com/blog/images/kool_aid.jpg http://www.swapmeetdave.com/Humor/Farts.htm

DIFFUSION across a space Diffusion continues until the concentration is ________________ in space = ________________________ equal everywhere Equilibrium http://lhs.lps.org/staff/sputnam/Biology/U3Cell/diffusion_1.png

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 across membrane …as long as membrane will let the molecule _________________ pass through

SELECTIVELY PERMEABLE (Semi-permeable) Video from: http://www.southtexascollege.edu/tdehne/BC_ShockwaveAnimations/08SWF-MembraneStructureAndFunct/08-02-MembraneStructure.swf SELECTIVELY PERMEABLE (Semi-permeable) See a movie http://life.nthu.edu.tw/~d857401/advance.html

CELL EXAMPLE: DIFFUSION automatically moves oxygen from HIGHER concentration (in lungs) to a LOWER concentration (in blood) CO2 automatically moves from where there is a HIGHER concentration (in blood) to where there is a lower concentration (in lungs) http://www.le.ac.uk/pa/teach/va/anatomy/case2/2_2.html

BUT…. What if a cell needs to move _____ or ______ molecules? LARGE POLAR http://www.d.umn.edu/~sdowning/Membranes/membraneImages/jpegimages/diffusionmedium.jpg

What if cell needs to move a molecule _________ the CONCENTRATION GRADIENT? _______________ AGAINST (LOWER  HIGHER) Cell example: Want to put MORE glucose into mitochondria when there is already glucose in there Image from: http://www.biologyclass.net/mitochondria.jpg

What if cell needs to move molecules really _______ What if cell needs to move molecules really _______? (can’t wait for it to diffuse) FAST Cell example: Movement of Na + & K+ ions required to send nerve signals http://www.steve.gb.com/images/science/neuron.png

We need a ____ to ____ molecules across cell membranes that _______ across by ___________ WAY HELP can’t go themselves

Kidspiration by: Riedell

Kinds of ________ Transport PASSIVE __________________________________ ___________________________________ Diffusion Osmosis Facilitated Diffusion

DIFFUSION across a membrane DIFFERENCE Happens anytime there is a __________ in _____________ on one side of the membrane compared to the other concentration Molecules that move by diffusion across membranes in cells: ______________ OXYGEN CARBON DIOXIDE See diffusion animation http://www.lionden.com/cell_animations.htm

OSMOSIS OSMOSIS DIFFUSION Semi-permeable lower = SPECIAL KIND OF DIFFUSION IMAGE by RIEDELL OSMOSIS ____________ See osmosis animation DIFFUSION __________ Movement of molecules across a _________________ membrane from ______ concentration to _____ Semi-permeable lower Higher

See a video about Passive transport 7-C

Facilitated Diffusion _______ proteins help diffusion go faster Carrier

FACILITATED DIFFUSION PASSIVE 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: _______________________ DOWN HIGHER to LOWER Membrane proteins GLUCOSE

Facilitated Diffusion Animation from: http://bio.winona.edu/berg/ANIMTNS/facdifan.gif

Kidspiration by: Riedell

Kinds of ________Transport ACTIVE ________________________________________ ___________________________________ ____________________________________ Sodium-Potassium Pump Endocytosis Exocytosis

See a video clip about Na+-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 ACTIVE ___________ 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 ATP Carrier Proteins

See a video clip about Endo/exocytosis -7E

ENDOCYTOSIS Takes substances into cell ACTIVE _____________transport (requires __________ from ______) Uses small membrane sacs called ______________ to carry substances energy ATP VESICLES http://www.sirinet.net/~jgjohnso/cell.html

2 KINDS of ENDOCYTOSIS Takes substances into cell If 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

Pinocytosis Called “Cell Drinking”

ENDOCYTOSIS Animation from: http://academic.brooklyn.cuny.edu/biology/bio4fv/page/cell-movement.html http://www.accs.net/users/kriel/chapter%20nine/

PHAGOCYTOSIS Called “Cell Eating” ___________ destroying _______ germs White blood cell germs ___________ destroying _______

EXOCYTOSIS Substances released outside of cell ACTIVE __________ transport (requires __________) Substances move in____________ Examples in cells: _________ release packaged proteins this way energy VESICLES GOLGI

Exocytosis http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBooktransp.html

GOLGI BODIES USE EXOCYTOSIS Video: http://www.southtexascollege.edu/tdehne/BC_ShockwaveAnimations/07SWF-TourOfTheCell/07-16-EndomembraneSystem.swf GOLGI BODIES USE EXOCYTOSIS Animation from: http://www.franklincollege.edu/bioweb/A&Pfiles/week04.html See a Golgi movie

Endocytosis & Exocytosis Videos from: http://www.pleasanton.k12.ca.us/avhsweb/thiel/apbio/notes/chp8/exocytosis_endocytosis.mov http://trc.ucdavis.edu/biosci10v/bis10v/week2/endocytosis.mov Endocytosis & Exocytosis Watch a video clip about endo/exocytosis Choose Screen/Switch programs to view

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 concentration reaches equilibrium

VOCAB _____________ = substance that is dissolved in a solvent to make a solution _____________ = substance in which a solute is dissolved SOLUTE SOLVENT EX: Koolaid powder = solute Water = solvent Koolaid drink = solution http://www.makash.ac.il/h_school/hst/hstsb/chem/luach/dissolve.jpg

Images by Riedell __________________ = mass of a solute in a given volume of solution CONCENTRATION MORE The _______ molecules there are in a given volume the ____________the concentration GREATER

See a video clip about OSMOSIS -7B

See an animation Osmosis1 http://faculty.etsu.edu/currie/images/osmosis1.jpg

OSMOSIS shrinks GREATER THAN Animation from: http://www.ouhscphysio.org/humanphys/animations/osmosis4.swf OSMOSIS See an animation OSMOSIS 4 HYPERTONIC: Concentration outside cell is ____________________ inside cell More water leaves cell than enters so cell ____________ GREATER THAN shrinks

Cell in Hypertonic Solution 15% NaCL 85% H2O ENVIRONMENT CELL 5% NaCL 95% H2O What is the direction of water movement?

OSMOSIS Swell and possibly burst LESS THAN Animation from: http://www.ouhscphysio.org/humanphys/animations/osmosis3.swf OSMOSIS See an animation Osmosis3 HYPOTONIC: Concentration outside cell is ________________ inside the cell More water enters than leaves cell so cell will ___________________ LESS THAN Swell and possibly burst

Cell in Hypotonic Solution 10% NaCL 90% H2O CELL 20% NaCL 80% H2O What is the direction of water movement?

OSMOSIS ISOTONIC: Concentration outside cell __________ EQUALS concentration inside cell Water entering = water leaving so cell _____________________ EQUALS STAYS THE SAME SIZE

Cell in Isotonic Solution 10% NaCL 90% H2O ENVIRONMENT CELL NO NET MOVEMENT 10% NaCL 90% H2O What is the direction of water movement? equilibrium The cell is at _______________.

NO NET MOVEMENT OF H2O (equal amounts entering & leaving) Isotonic Solution Hypotonic Solution Hypertonic Solution NO NET MOVEMENT OF H2O (equal amounts entering & leaving) Cell Swells & may burst Cell shrivels up

Animal cells http://www.stchs.org/science/courses/sbioa/metenergy/bloodcells.gif

Osmosis in Red Blood Cells Isotonic Hypertonic Hypotonic

Plant cells _____ keeps CELL WALL Plant cells from bursting http://www.stchs.org/science/courses/sbioa/metenergy/aplantturgor.gif Plant cells CELL WALL _____ keeps Plant cells from bursting

VACUOLES store WATER OSMOTIC PRESSURE _____________________________ = http://www.biology4kids.com/files/cell_vacuole.html OSMOTIC PRESSURE _____________________________ = Pressure exerted by water during osmosis

SO WHAT? hypotonic Bath water is ________________ compared to you Sitting in the bathtub causes your fingers and toes to wrinkle up when water ________ your skin cells by osmosis enters

Grocery stores spray water on their veggies to “plump them up” http://www.painetworks.com/photos/gt/gt0461.JPG

SO WHAT?