Cell TransportCell TransportLecture #17Lecture #17

Ms. DayMs. DayHonors BiologyHonors Biology

Cell TransportMeans moving things INTO and OUT of the cell

Cells need to take in Food, gases, waterGet rid of waste productsRelease hormones and enzyme

REVIEW…REVIEW…Permeability and Cell TransportPermeability and Cell Transport

Hydrophobic (non polar) moleculesAre lipid soluble (can dissolve) can pass through membrane easily

Ex: CO2, O2

Hydrophilic (Polar) moleculesAre NOT lipid soluble (can’t dissolve)

Lipid INsolubleDo not cross membrane easily

Ex: Na+, Cl- , Glucose/other polar or charged things

Types of Cellular Transport Passive Transport

cell do NOT use energy1. Diffusion/Osmosis2. Facilitated Diffusion

Active Transportcell DOES use energy

1. Protein Pumps2. Endocytosis3. Exocytosis

high

low

This is going to be hard!

high

low

Weee!

Types of Passive Transport

DiffusionDiffusion= molecules (of ANYANY substance) move from area of HIGH [ ] to lower [ ] A “net” movement

Ex: Perfume, a fart , tea, food coloring in water

http://www.indiana.edu/~phys215/lecture/lecnotes/lecgraphics/diffusion2.gif

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

DIFFUSION DIFFUSION Molecules move DOWN

its OWNOWN concentration gradient

difference in amount of a substance from one area to another

No chemical work (ATP energy) is used

Substances diffuse down their Substances diffuse down their OWN concentration gradientOWN concentration gradient

Net diffusion

Net diffusion

Net diffusion

Net diffusion Equilibrium

Equilibrium

Effects of Osmosis on Effects of Osmosis on Water BalanceWater Balance

Osmosis Diffusion of

waterwater across a semipermeablsemipermeable membranee membraneWater molecules Water molecules

move from MORE move from MORE water to LESS water to LESS waterwater

3 Different Types of Solutions3 Different Types of Solutions** compare solutions OUTSIDE cell to inside cell** compare solutions OUTSIDE cell to inside cell

1. Isotonic solutionAmount of solutes and water is the

same outside cell as inside the cell“iso-” means “same”

There will be NONO net movement of water

Cell does not change in size

ISOTONIC SOLUTION

Result: Water moves equally in both directions and the cell remains same size! (Dynamic

Equilibrium)

2. Hypertonic solutionHypertonic solution Amount of solutes is greater

outside than inside the cell “hyper” means more

high [solute]

The cell will lose water and shrivel or wilt

HYPERTONIC SOLUTION

Result: Water moves from inside the cell into the solution: Cell shrinks!

3.3. Hypotonic solutionHypotonic solutionAmount of solutes is less

outside than inside the cell“hypo” means “less”

• low [solute]Think: Hypo- sounds like

hippo…hippos are big & round; cells in hypotonic solutions get big & roundAlso, think “hypo” is “low” meaning

“low” solutes SURROUNDING cell The cell will gain water and swell

(and maybe burst)

“Hypo” is LOW!!!

HYP0TONIC SOLUTION

Result: Water moves from the solution to inside the cell): Cell Swells and might burst

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html

• Osmosis Animations for

isotonic, hypertonic, and hypotonic

solutions

REVIEW…Types of Passive Transport

#1 #1 Passive TransportDOES NOT require ATP energy Moves DOWN (WITH) [ ] gradient Kinetic energy drives movementKinetic energy drives movement

#2 #2 Active TransportDOES require chemical energy (Ex: ATP)

Moves AGAINST its [ ] gradient

2 Types of PASSIVE TRANSPORT

2 Types of PASSIVE TRANSPORT2. FACILITATED DIFFUSION. FACILITATED DIFFUSIONneeds a little “help”needs a little “help”Uses help of Uses help of channel or carrier channel or carrier

proteinsproteins GOES DOWN CONCENTRATION GRADIENT (no ATP needed)

Moves Moves POLARPOLAR molecules molecules can can NOT NOT easily pass through easily pass through HYDROPHOBIC region of membrane. HYDROPHOBIC region of membrane. Example: ions, smaller polar molecules (ex: Example: ions, smaller polar molecules (ex:

sugar)sugar)

Aquaporinswater is polar but very

smallIt can pass easily through

membrane uses aquaporins Oh…now

I get it!EXTRACELLULARFLUID

AQUAPORINChannel protein

Water CYTOPLASM

Channel proteins-Provide “tunnels”

EXTRACELLULARFLUID

Channel proteinSolute

CYTOPLASM

A channel protein (purple) has a channel through which water molecules or a specific solute can pass.

(a)

• Channel Proteins animations

Carrier proteins-Undergo a subtle change in shape “carry” solute across the membrane

Carrier protein Solute

2 Types of Passive Transport

Active transportActive transportUses energyenergy Moves solutes against

their [ ] gradients across the cell membraneEnergyEnergy required

usually ATPATPCarrier proteinsCarrier proteins are used…

NEVER channel proteinsEx: protein pumps

Passive vs. Active Passive vs. Active TransportTransport

Figure 7.17

Another type of transport = Bulk Another type of transport = Bulk TransportTransport

Occurs by exocytosisexocytosis and endocytosisendocytosis

BOTH MOVE “BIG” BOTH MOVE “BIG” AMOUNTS OF STUFF in OR AMOUNTS OF STUFF in OR

out OF THE CELLout OF THE CELL

ExoExocytosiscytosisIn exocytosisexocytosis

Transport vesicles move to the plasma membrane, fuse with it, and release their contents

“exo-” means “exit”Ex: hormone excretion; nerve cells and transmitters; removal

of wastes

EndoEndocytosiscytosisIn endocytosisendocytosis

Cell takes in molecules by forming new vesicles from the plasma membrane

“endo-” means “enter”

2 types of Endocytosis2 types of Endocytosis1. Phagocytosis 1. Phagocytosis

“cell eating” Cell engulfs SOLIDS

into vesicle & “digests” it

2. Pinocytosis2. Pinocytosis “cell drinking” Cell engulfs LIQUIDS

into vesicle & “digests” it

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__phagocytosis.html

Endocytosis and Exocytosis Animations

http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter6/animations.html#

REVIEW ANIMATIONS

http://www.northland.cc.mn.us/biology/Biology1111/animations/passive3.swfExcellent Review all Passive

(simple/facilitated diffusion) and Active Transport No verbal explanation…you have to read the

tutorial!