Cellular Cellular TransportTransport

Functions of the cell membrane.Functions of the cell membrane.

1. Provides boundary for cell

2. Selectively permeable- only allows certain things to pass through- “Picky”

Ex. Window screen

3. Maintains homeostasis: balance within the cells

Relate the structure of the cell Relate the structure of the cell membrane to its function.membrane to its function.

Membrane is Membrane is a lipid a lipid bilayerbilayerfluid-mosaic modelfluid-mosaic modelPhospholipids:Phospholipids: fatty fatty areas that attract areas that attract (hydrophillic) and repel (hydrophillic) and repel (hydrophobic) water(hydrophobic) waterEmbedded proteins:Embedded proteins: “bouncers”“bouncers”

1.1. Decide who goes in & Decide who goes in & outout

2.2. Markers for recognitionMarkers for recognition

DiffusionDiffusionmovement of particles from high to low concentration

Ex. Perfume & Body odor

OSMOSIS

movement of water from high

to low concentration. Both

Go through bilayer

Do NOT require cell energy (passive transport)

Move until equilibrium is reached

High concentration

Low concentration

Osmosis Diffusion

Cells in solutions.Cells in solutions.

Compare the three types of Compare the three types of solutions.solutions.

ISOTONICISOTONIC: same strength: same strength

particles outside = particles particles outside = particles insideinside

ISO- means “equal to”ISO- means “equal to”

Movement into cell= Movement into cell= movement out of cellmovement out of cell

•HYPOTONIC: concentration of dissolved substances is lower outside cell than inside cell

•HYPO means “below strength”

•Water will move INTO cell causing it to swell (it always moves to where there is more substances)

•Cells could rupture if the cell takes in too much water

•This increases pressure inside of cell (TURGOR PRESSURE)

•HYPERTONIC: concentration of dissolved substances is higher outside the cell

•HYPER means “above strength”

•Water rushes OUT of cell causing it to shrivel (water rushes to where there is more substances)

•Can result in PLASMOLYSIS in plants which causes wilting

•FACILITATED DIFFUSION:

•type of diffusion since movement is from high to low concentration, but this type goes through a protein channel rather than bilayer.

•Also Passive Transport

•Proteins –picky “bouncers”

Glucosemolecules

ProteinchannelLow

Concentration

HighConcentration

ACTIVE TRANSPORT:ACTIVE TRANSPORT: transporttransport against against concentration gradient; concentration gradient; goes from goes from low to highlow to high concentrationconcentration

Go through protein Go through protein channelchannel

This requires energy to This requires energy to move them into cell; ex: move them into cell; ex: Na-K pumpNa-K pump

Molecule tobe carried

Moleculebeing carried

Energy

LowConcentration

HighConcentration

•Types of active transport:

•ENDOCYTOSIS: cells take in large clumps of substances

•Phagocytosis: “cell eating” take in food

•Pinocytosis: “cell drinking” take in water

•EXOCYTOSIS: cells move substances out(exit)

ex: wastes

SummarySummaryDiffusion & OsmosisDiffusion & Osmosis/ high to low conc./ go in between / high to low conc./ go in between phospholipid spaces/ no energy= phospholipid spaces/ no energy= Passive transportPassive transportFacilitated DiffusionFacilitated Diffusion- high to low/ no energy/ goes through - high to low/ no energy/ goes through proteinproteinActive transportActive transport- low to high conc./ requires energy/ goes - low to high conc./ requires energy/ goes through proteinthrough protein

Ex. Party Ex. Party `̀ 1. Air coming into a window screen1. Air coming into a window screen 2. Someone opens the door & you walk 2. Someone opens the door & you walk

through (door represents protein)through (door represents protein)3. someone goes through the back door that is 3. someone goes through the back door that is already openalready open

*coming in=Endocytosis going out= Exocytosis*coming in=Endocytosis going out= Exocytosis