Cells & Their Environment Inside & Out THE CELL MEMBRANE ISTHE CELL MEMBRANE IS Semi permeable or Selectively permeableSemi permeable or Selectively

Cells & Their Cells & Their EnvironmentEnvironment

Inside & OutInside & Out• THE CELL MEMBRANE ISTHE CELL MEMBRANE IS

• Semi permeable Semi permeable oror Selectively permeable Selectively permeable

Allow certain materials through but not Allow certain materials through but not othersothers

• What can pass & What can not?What can pass & What can not?

PASSPASS NO PASS (W/O help) NO PASS (W/O help)

Small MoleculesSmall Molecules Large MoleculesLarge Molecules

((WATERWATER)) (MACRO MOLECULES)(MACRO MOLECULES)

IONSIONS

TRANSPORT ME OUTTA TRANSPORT ME OUTTA HEREHERE

• Two types of processes Two types of processes help molecules help molecules move across the membranemove across the membrane ( (Active & Active & Passive TransportPassive Transport))

ACTIVE ACTIVE PASSIVEPASSIVE

USES ENERGYUSES ENERGY NO NO ENERGYENERGY

PASSIVE TRANSPORT: PASSIVE TRANSPORT: DIFFUSIONDIFFUSION

• Most common form is Most common form is DIFFUSIONDIFFUSIONWhich is the Which is the movement of molecules movement of molecules fromfrom an area of an area of high concentration tohigh concentration to

an area of an area of low concentrationlow concentration(This is called(This is calledmovement alongmovement alongthe concentrationthe concentrationgradient) I’ll talk moregradient) I’ll talk morelaterlater

PASSIVE TRANSPORT : PASSIVE TRANSPORT : DIFFUSIONDIFFUSION

• WhatWhat affects the rateaffects the rate of of DIFFUSIONDIFFUSION??

1.1. TempTemperature: erature: HigherHigher Temps = Temps = FASTERFASTER

2.2. SizeSize of Molecules: of Molecules: SmallerSmaller Molecules = Molecules = FASTERFASTER

3.3. Concentration: Higher Concentration: Higher [ ]of molecules[ ]of molecules = Faster= Faster


DIFFUSIONDIFFUSION always always occurs occurs down a down a concentration gradientconcentration gradient

• Concentration gradient = Concentration gradient = difference between the concdifference between the conc. of a . of a particular molecule particular molecule in one areain one area and and the concentration in the concentration in a a nearby or adjacent areanearby or adjacent area


• When both areas have the same When both areas have the same amount of molecules (amount of molecules (dispersed dispersed evenly = STATE OF EQUILIBRIUMevenly = STATE OF EQUILIBRIUM) ) diffusion stopsdiffusion stops

• Some Some molecules need a protein’s helpmolecules need a protein’s help to move to move across membraneacross membrane this is this is called called FACILITATED DIFFUSIONFACILITATED DIFFUSION

PASSIVE TRANSPORTPASSIVE TRANSPORTFACILITATED DIFFUSIONFACILITATED DIFFUSION

• During this type of diffusion During this type of diffusion LARGE LARGE moleculesmolecules (MACRO MOLECULES & (MACRO MOLECULES & IONS) IONS) move down conc. gradient move down conc. gradient fasterfaster

• This is how GLUCOSE is transported This is how GLUCOSE is transported from the blood into body cellsfrom the blood into body cells

REVIEWREVIEW

• What does What does ACTIVE TRANSPORTACTIVE TRANSPORT mean? mean?

• What does What does PASSIVE TRANSPORTPASSIVE TRANSPORT mean?mean?

• Define Define STATE OF EQUILIBRIUMSTATE OF EQUILIBRIUM

• What is What is FACILITATED DIFFUSIONFACILITATED DIFFUSION??

OSMOSIS: WATERS WAYOSMOSIS: WATERS WAY

• What is it?What is it?

The The diffusion of WATERdiffusion of WATER across a across a semi-semi- permeable membranepermeable membrane

• Form of Form of PASSIVE TRANSPORTPASSIVE TRANSPORT

• Happens Happens when two sides of membrane when two sides of membrane have different concentrations ofhave different concentrations of SOLUTESSOLUTES


• Just like otherJust like other DIFFUSINGDIFFUSING moleculesmolecules water moves from water moves from HIGH to LOW concentrationsHIGH to LOW concentrations

• Let me say that againLet me say that again::


WATER MOVES FROM WATER MOVES FROM HIGH HIGH

CONCENTRATIONS TO CONCENTRATIONS TO LOW LOW

CONCENTRATIONSCONCENTRATIONS

Solute/Solvent What’s Solute/Solvent What’s the Dif?the Dif?

• Solute is what is dissolved Solute is what is dissolved (gatorade powder, iced tea, (gatorade powder, iced tea, hot chocolate)hot chocolate)

• Solvent is what does the Solvent is what does the dissolving (usually water)dissolving (usually water)

• Solution is the result of Solution is the result of mixing solutes and solventmixing solutes and solvent


• THESE NEXT TWO THINGS ARE THESE NEXT TWO THINGS ARE KEY KEY (MEMORIZE THEM)(MEMORIZE THEM)

• HIGH WATERHIGH WATER concentration concentration == LOW SOLUTELOW SOLUTE concentration concentration

• LOW WATERLOW WATER concentration is concentration is = = HIGH SOLUTEHIGH SOLUTE concentration concentration


• Water has a natural tendency to Water has a natural tendency to FLOW FROM FLOW FROM LOW SOLUTELOW SOLUTE TO TO HIGH SOLUTEHIGH SOLUTE CONCENTRATIONSCONCENTRATIONS

• Low solute = high water concLow solute = high water conc• High solute = low water concHigh solute = low water conc

• This has an effect on cellsThis has an effect on cells


(We are talking from the POV of solutes (We are talking from the POV of solutes here)here)

1.1. IsotonicIsotonic

""ISOISO" means the same" means the same

If the concentration of If the concentration of solute is equal solute is equal on both sides of the cell membraneon both sides of the cell membrane, , the water will move back and forth but the water will move back and forth but it it won't have any result on the overall won't have any result on the overall amount of water on either sideamount of water on either side..


2.2. HypotonicHypotonic""HYPOHYPO" means less" means less there are there are LESS SOLUTE MOLECULES LESS SOLUTE MOLECULES OUTSIDE THE CELLOUTSIDE THE CELL, water will move , water will move into the cell.into the cell.

• CELL WILL GAIN WATER AND GROW CELL WILL GAIN WATER AND GROW LARGER.LARGER.

• REMEMBER WATER MOVES FROM LOW REMEMBER WATER MOVES FROM LOW

SOLUTE TO HIGH SOLUTESOLUTE TO HIGH SOLUTE


3.3. HypertonicHypertonic

""HYPERHYPER" means more" means more

there are there are MORE SOLUTE MORE SOLUTE MOLECULES OUTSIDE THE CELLMOLECULES OUTSIDE THE CELL, , which causes the water to be sucked in which causes the water to be sucked in that direction.that direction.

• CELLS SHRINKCELLS SHRINK • REMEMBER WATER MOVES FROM REMEMBER WATER MOVES FROM

LOW SOLUTE TO HIGH SOLUTELOW SOLUTE TO HIGH SOLUTE



• Remember water moves from high to Remember water moves from high to lowlow

BUT BUT

The terms ISO, HYPO, & HYPER The terms ISO, HYPO, & HYPER are talking about the SOLUTES are talking about the SOLUTES

and how water moves based on their and how water moves based on their concentrationsconcentrations

REVIEWREVIEW

• What is OSMOSIS?What is OSMOSIS?

• What is WATER’S natural tendency?What is WATER’S natural tendency?

• What do the terms HYPO, HYPER, & What do the terms HYPO, HYPER, & ISO mean?ISO mean?

• What concentration are they What concentration are they referring to, the water or the solutes?referring to, the water or the solutes?

ACTIVE TRANSPORT: ACTIVE TRANSPORT: MOVIN’ ON UPMOVIN’ ON UP

• Uses energyUses energy to to move move againstagainst the the conc. gradientconc. gradient (moving up a gradient)(moving up a gradient)

• Move fromMove from areas of areas of low to low to highhigh concentrationconcentration

• Similar to Similar to Facilitated Facilitated DiffusionDiffusion ( (Uses carrier Uses carrier proteinsproteins))

• Energy comes from ATP Energy comes from ATP (Adenosine Tri (Adenosine Tri

Phosphate)Phosphate)

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Cells & Their Environment Inside & Out THE CELL MEMBRANE ISTHE CELL MEMBRANE IS Semi permeable or Selectively permeableSemi permeable or Selectively