honors biology cellular transport. diffusion the net movement of particles from an area of high...

Honors BiologyHonors BiologyCellular TransportCellular Transport

DiffusionDiffusion

The net movement of particles from an area of high concentration to an area of low concentration

High concentration Low concentration

Equal distribution

DiffusionDiffusion

Movement goes with the concentration gradient– From areas of high concentration to areas

of low concentration

OsmosisOsmosis

Diffusion of water through a selectively permeable membrane

Goes with the concentration gradient

OsmosisOsmosis

Weaksolution

Strongsolution

WATER

(Lots of water molecules) (Few water molecules)

Selectively permeablemembrane

Weaksolution

Strongsolution

Membraneallows

water topass but

not solutes

Solutions with equalconcentrations

OsmosisOsmosis

Special terms for referring to strong or weak solutions

OsmosisOsmosis

Special terms for referring to strong or weak solutions– Isotonic: two solutions with equal

concentrations of solutes

OsmosisOsmosis

Special terms for referring to strong or weak solutions– Isotonic: two solutions with equal

concentrations of solutes– Hypertonic: solution with high concentration

of solutes (strong solution)

OsmosisOsmosis

Special terms for referring to strong or weak solutions– Isotonic: two solutions with equal

concentrations of solutes– Hypertonic: solution with high concentration

of solutes (strong solution)– Hypotonic: solution with low concentration

of solutes (weak solution)

OsmosisOsmosis

Hypotonic HypertonicWATER

When does diffusion/osmosis stop?When does diffusion/osmosis stop?

Never! When it reaches a homeostatic balance equal numbers of molecules are

moving in both directions!

Turgor PressureTurgor Pressure

The pressure inside a cellMaintained via osmosis

Turgor PressureTurgor Pressure

Plasmolysis

Contractile VacuolesContractile Vacuoles

Lysis

Cellular TransportCellular Transport

Passive: goes with concentration gradient

Active: goes against concentration gradient

Cellular TransportCellular Transport

PassiveActiveEndo- and Exocytosis

Cellular TransportCellular Transport

Passive– Simple diffusion through the lipid bilayer– Simple diffusion through an ion channel– Facilitated diffusion

ActiveEndo- and Exocytosis

Passive TransportPassive Transport

Simple diffusion through the lipid bilayerSimple diffusion through an ion channelFacilitated diffusion

Simple diffusion through the lipid Simple diffusion through the lipid bilayerbilayerSmall, non-polar molecules

– O2 and CO2

OsmosisGoes with concentration gradient

Passive TransportPassive Transport

Simple diffusion through the lipid bilayerSimple diffusion through an ion channelFacilitated diffusion

Simple diffusion through an ion Simple diffusion through an ion channelchannelIons are highly polar and cannot pass

through the lipid bilayerIons are critical to cell functioning

– Na+, K+, Ca+, and Cl-

Simple diffusion through an ion Simple diffusion through an ion channelchannelPass readily through a water-filled pore

formed by an integral membrane protein

Simple diffusion through an ion Simple diffusion through an ion channelchannelMovement is bi-directionalChannels are specialized for a single ion Goes with concentration gradient

Passive TransportPassive Transport

Simple diffusion through the lipid bilayerSimple diffusion through an ion channelFacilitated diffusion

Facilitated DiffusionFacilitated Diffusion

Diffusion is aided by a carrier protein (integral membrane protein)

Facilitated DiffusionFacilitated Diffusion

Molecule to be transported physically binds to the carrier protein on one side of the membrane

Protein undergoes a conformational change that does not require energy

Molecule is released on the other side of the membrane

Facilitated DiffusionFacilitated Diffusion

Molecule is attracted to a specific carrier protein

Facilitated DiffusionFacilitated Diffusion

Molecule binds to carrier protein

Facilitated DiffusionFacilitated Diffusion

Carrier protein undergoes conformational change and releases molecule on other

side of membrane

Facilitated DiffusionFacilitated Diffusion

Movement is bi-directionalCarrier proteins are specialized for a

single ion or moleculeGoes with concentration gradientPassive process

Cellular TransportCellular Transport

PassiveActiveEndo- and Exocytosis

Active TransportActive Transport

Similar to facilitated diffusion– Molecule to be transported physically binds

to the carrier protein on one side of the membrane and is released on the other side of the membrane via a shape change of the protein

Active TransportActive Transport

Goes against concentration gradientRequires energy input from the cell

Active TransportActive Transport

Active TransportActive Transport

Active TransportActive Transport

Bi-directionalCarrier proteins are specialized to move

a single substance

Active TransportActive Transport

Sodium-Potassium (Na-K) PumpCotransportCountertransportProton Pump (Next chapter)

NaNa++ - K - K++ Pump Pump

Cell needs low Na+ and high K+ relative to external environment

Ions are “pumped” into and out of the cell via an integral membrane protein

Na+ concentration becomes form of stored energy for cotransport

CotransportCotransport

Na+ is pumped into cell with concentration gradient

Simultaneously sugar or amino acid is pumped into cell against concentration gradient

CountertransportCountertransport

Na+ is pumped into cell with the concentration gradient

Ca+ or H+ is pumped into cell against the concentration gradient

Cellular TransportCellular Transport

PassiveActiveEndo- and Exocytosis

Endo- and ExocytosisEndo- and Exocytosis

Used to move large amounts of materials into or out of a cell quickly

Requires energy

EndocytosisEndocytosis

Cell consumes large molecules or other cells

Cytoskeleton extends plasma membrane outward toward particle, encircles the it, and contracts membrane back inwards, engulfing particle

EndocytosisEndocytosis

2 types– Phagocytosis– Pinocytosis

EndocytosisEndocytosis

Phagocytosis: “Cell eating”– Cell takes in solid particles

EndocytosisEndocytosis

Pinocytosis: “Cell drinking”– Cell takes in liquid materials

ExocytosisExocytosis

Cell excretes large wastesMechanism for releasing hormones