Cellular Cellular TransportTransport

Cellular Transport involves Cellular Transport involves the the Cell MembraneCell Membrane!!

• PASSIVE TRANSPORTPASSIVE TRANSPORT– Energy not requiredEnergy not required

•DIFFUSIONDIFFUSION•OSMOSISOSMOSIS

– HypertonicHypertonic– HypotonicHypotonic– IsotonicIsotonic– OsmoregulationOsmoregulation

•FACILITATED FACILITATED DIFFUSIONDIFFUSION

• ACTIVE ACTIVE TRANSPORTTRANSPORT– Energy Energy

REQUIREDREQUIRED!!•ENDOCYTOSISENDOCYTOSIS

– Carrier Carrier MediatedMediated

– PhagocytosisPhagocytosis– PinocytosisPinocytosis

•EXOCYTOSISEXOCYTOSIS

–Passive TransportPassive Transport = Energy not required.1. DiffusionDiffusion = molecules move from an area of high concentration to an area of low concentration.

DiffusionDiffusion is the driving force behind the movement of many substances across the cell membrane.

More on diffusion

• http://www.youtube.com/watch?v=STLAJH7_zkY

DiffusionDiffusion will occur IFIF:A.There is a concentration concentration

gradientgradient across the cell membrane.

B.Solution or membrane is permeablepermeable.

NOTE! The cell membrane is NOTE! The cell membrane is semi-semi-permeablepermeable, which means only , which means only small molecules or fat soluble small molecules or fat soluble molecules can pass across the molecules can pass across the membrane without help.membrane without help.

Permeable:Permeable: It can pass. It can pass.ImpermeableImpermeable: Cannot : Cannot pass.pass.

22ndnd Type of Passive Type of Passive Transport:Transport:

OsmosisOsmosis: The diffusion of waterwater across the cell cell membrane.membrane.

How does How does water know water know whether to whether to move into or move into or out of a cell?out of a cell?

Hypertonic solution:Hypertonic solution: The solution with the higher concentration of solutes.Hypotonic solution:Hypotonic solution: The solution with a lower solute concentration.

•Isotonic solution:Isotonic solution: Solutions of equal concentration of solutes.

Egg Cell in hypertonic vs. hypotonic solution

• http://www.youtube.com/watch?feature=endscreen&NR=1&v=SSS3EtKAzYc

33rdrd Type of Type of Passive Transport: Passive Transport:3. Facilitated Diffusion:Facilitated Diffusion: Molecules

are transported across the cell membrane by a carrier protein.

Ex. Glucose is carried into a red blood cell by a carrier protein.

Cell SurvivalSurvival Depends on the Proper Balancing of WaterWater

Uptake and Loss

•AnimalsAnimals that live in hypo-hypo- or hypertonichypertonic environments must have adaptationsadaptations for osmoregulationosmoregulation.

•The protist ParameciumParamecium has a contractile vacuole that pumps water out as it enter.

Paramecium – vacuole pumping out water

 

• http://www.youtube.com/watch?v=pahUt0RCKYc&feature=related  

•    

•The cells of plants, The cells of plants, prokaryotes, and fungi have prokaryotes, and fungi have cells walls, which keeps the cells walls, which keeps the cell from bursting.cell from bursting.

•A cell is turgidturgid (firm) when the back pressure of the cell wall on the cell opposed any further water uptake.

•A cell is A cell is flaccidflaccid ((limplimp) when ) when its surroundings are isotonic its surroundings are isotonic and there is no net tendency and there is no net tendency for water to enter the cell.for water to enter the cell.

Active TransportActive Transport•Essential in the ability of a cell to

maintain internal concentrations of small molecules.

It is the pumping of molecules against their gradients.ATP supplies the energy.

Sodium-Potassium Sodium-Potassium PumpPump exchanges Na+ for K+ exchanges Na+ for K+ across the plasma membrane of across the plasma membrane of

an animal cell.an animal cell.

https://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html

•All cells have electrical potential energy (voltage) across their plasma membranes. This is called a membrane potential.membrane potential.

•The inside of a cell is ---, and the outside is +, which causes the membrane to favor the passive transport of cations into the cell.

ACTIVE TRANSPORT

1.1. EndocytosisEndocytosis = The cell membrane surrounds and engulfs large particles.

1.1.Carrier Mediated EndocytosisCarrier Mediated Endocytosis = involves carrier proteins on membrane

2.2.PhagocytosisPhagocytosis = Cells bring in large, solid particles (“cellular eating”)

3.3.PinocytosisPinocytosis = Cells take up liquid. (“cellular drinking”)

Carrier Mediated EndocytosisCarrier Mediated Endocytosis

PhagocytosisPhagocytosis (Endocytosis)(Endocytosis)

Pinocytosis Pinocytosis (Type of Endocytosis)(Type of Endocytosis)

2.2. Exocytosis Exocytosis = Cells remove large particles.

Exocytosis

The End