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Cellular Transport and Cellular Transport and the Cell Cyclethe Cell Cycle

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Diffusion—Movement of Diffusion—Movement of particles from an area of particles from an area of

higher concentrationhigher concentration to an to an area of area of lower concentrationlower concentration

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Net MovementNet Movementmovement which changes movement which changes

concentrationconcentration

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Factors that affect diffusionFactors that affect diffusion

Particle size and shapeParticle size and shapeTemperatureTemperatureConcentration gradient—Difference in Concentration gradient—Difference in

concentration.concentration.Cytoplasmic streaming—Continuous Cytoplasmic streaming—Continuous

movement of materials in cytoplasm.movement of materials in cytoplasm.

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Diffuse in MembranesDiffuse in Membranes1.1.

Passive TransportPassive TransportMoving of materials across cell membrane Moving of materials across cell membrane

without using cellular energy.without using cellular energy.•Diffusion (phospholipids) Diffusion (phospholipids)

•Facilitated Diffusion (transport proteins) Facilitated Diffusion (transport proteins) Uses Channel ProteinsUses Channel Proteins

Active TransportActive TransportMoving of materials across cell membrane Moving of materials across cell membrane

using cellular energyusing cellular energyUses Carrier ProteinsUses Carrier Proteins

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OsmosisOsmosis

• Diffusion of Diffusion of WATERWATER across a across a selectively permeable selectively permeable

membrane.membrane.• Water moves from an area of Water moves from an area of

HIGH water concentration (low HIGH water concentration (low solute) to an area of LOW solute) to an area of LOW water concentration (high water concentration (high

solute)solute)

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OsmosisOsmosis

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Osmotic PressureOsmotic PressureForce produced by the net movement of Force produced by the net movement of

water out of or into cell.water out of or into cell.Result:Result:Turgid pressure-plants straight upTurgid pressure-plants straight upWater purification (reverse osmosis)Water purification (reverse osmosis)Desalinates Salt WaterDesalinates Salt Water

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Osmotic Condition—Cell Osmotic Condition—Cell concentrations versus concentrations versus environmental solution environmental solution

concentrations.concentrations.

IsotonicIsotonicHypotonicHypotonicHypertonicHypertonic

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IsotonicIsotonic“Iso” means same“Iso” means same

Solution concentrations inside is the same as Solution concentrations inside is the same as outside.outside.

No net movement of water.No net movement of water.Animal cells: NormalAnimal cells: NormalPlant Cells: FlaccidPlant Cells: Flaccid

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Solute concentrations outside is Solute concentrations outside is less than cell concentration.less than cell concentration.

Animal Cell : LysedAnimal Cell : LysedPlant Cell: TurgidPlant Cell: Turgid

““Hypo” - underHypo” - under

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Solute concentration outside is Solute concentration outside is greater than cell concentration.greater than cell concentration.

Animal Cell: ShrinkAnimal Cell: ShrinkPlant Cell: PlasmolyzedPlant Cell: Plasmolyzed

““Hyper” - aboveHyper” - above

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This is why it is dangerous to drink sea water - its a myth that drinking sea water will cause you to go insane, but people marooned at sea will speed up dehydration (and death) by drinking sea water.

This is also why "salting fields" was a common tactic during war, it would kill the crops in the field, thus causing food shortages.

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Hypertonic, Isotonic and Hypertonic, Isotonic and HypotonicHypotonic

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AActive ctive TTransransPPortort

Using a protein molecule to move Using a protein molecule to move particles up the concentration particles up the concentration

gradient.gradient.Requires ATP (Adenosine Requires ATP (Adenosine

Triphosphate)Triphosphate)

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Example of how the cell Example of how the cell uses Active Transportuses Active Transport

Pump—Proteins that use active Pump—Proteins that use active transport to move particles transport to move particles

between the interior and exterior between the interior and exterior of the cell.of the cell.

e.g. Sodium/Potassium pump: e.g. Sodium/Potassium pump: Used to move sodium and Used to move sodium and

potassium ions across nerve potassium ions across nerve membranes.membranes.

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Active Transport Versus Active Transport Versus Passive TransportPassive Transport

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Large MoleculesLarge Molecules

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Endocytosis: Cell membrane Endocytosis: Cell membrane indents around molecule and indents around molecule and

forms a vesicle.forms a vesicle.

Pinocytosis—Uptaking fluid moleculesPinocytosis—Uptaking fluid moleculesPhagocytosis—Uptaking solid moleculesPhagocytosis—Uptaking solid molecules

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Pinocytosis and PhagocytosisPinocytosis and Phagocytosis

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ExocytosisExocytosis

Vesicles fuse with cell membrane Vesicles fuse with cell membrane to release materials.to release materials.

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Endocytosis and ExocytosisEndocytosis and Exocytosis

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Cell SizeCell Size

Cell size range from 8 micrometers in Cell size range from 8 micrometers in diameter to 1 meter with small diameter to 1 meter with small diameters.diameters.

Most cells are between 2 and 200 Most cells are between 2 and 200 micrometers in diameter.micrometers in diameter.

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Comparison of Cell sizesComparison of Cell sizes

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Cell Size LimitationsCell Size Limitations

Cell must be smallCell must be small– larger cells find it difficult to bring in enough foodlarger cells find it difficult to bring in enough food– export enough waste to keep the cell alive.export enough waste to keep the cell alive.

Rate of DiffusionRate of Diffusion– Size :diffusion slower and less efficient.Size :diffusion slower and less efficient.

DNA—Cell cannot survive unlessDNA—Cell cannot survive unless– enough DNA to support protein needs of cellenough DNA to support protein needs of cell– cell activities are carried out quickly and cell activities are carried out quickly and

efficientlyefficiently

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Surface area-to-volume ratioSurface area-to-volume ratio

Another size limiting factor is the Another size limiting factor is the cell’s surface area-to-volume ratio. cell’s surface area-to-volume ratio.

As cell’s size increases, its As cell’s size increases, its volume increases much faster volume increases much faster

than its surface area.than its surface area.

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Cell Surface area-to-volume ratioCell Surface area-to-volume ratio

As cell size increases, the ratio of cell volume to cell surface area decreases.

Cells increase in size, there isn't enough cell membrane to adequately supply the cell interior with enough oxygen,

water, and food.

When this happens, the cell dies.

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Cell Growth and ReproductionCell Growth and Reproduction

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Cell TheoryCell TheoryAll cells come from pre-existing All cells come from pre-existing

cells!cells!

Cell division results in two cells Cell division results in two cells that are identical to the original that are identical to the original

parent cell.parent cell.

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ChromosomesChromosomesChromaChroma (Greek) “colored” (Greek) “colored”

SomaSoma “body” “body”Dark-staining structures that contain Dark-staining structures that contain genetic information that is crucial to genetic information that is crucial to

the identity of the cell.the identity of the cell.

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Structure of the Eukaryotic Structure of the Eukaryotic ChromosomeChromosome

Exist as CHROMATIN—Long strands of Exist as CHROMATIN—Long strands of DNA wrapped around proteins.DNA wrapped around proteins.

Microscope—Plate of spaghettiMicroscope—Plate of spaghetti

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Cell CycleCell Cycle

The cell cycle The cell cycle

– InterphaseInterphase (most of the cell’s metabolic (most of the cell’s metabolic functions are carried out and the chromosomes functions are carried out and the chromosomes are replicated) LONGEST of Cell Cycleare replicated) LONGEST of Cell Cycle

– MitosisMitosis when nuclear division occurs, leading to when nuclear division occurs, leading to the formation of two daughter cells.the formation of two daughter cells.

– The division of the cytoplasm, called The division of the cytoplasm, called cytokinesiscytokinesis, follows mitosis., follows mitosis.

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Cell Cycle: Sequence of growth Cell Cycle: Sequence of growth and cell division of a celland cell division of a cell

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InterphaseInterphase

Cell grows in sizeCell grows in sizeCarry on metabolismCarry on metabolismChromosomes are duplicated for cell Chromosomes are duplicated for cell

division.division.

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Interphase:Cell Prepares for Interphase:Cell Prepares for MitosisMitosisG1: Chromosomes are not visible under light (uncoiled); Protein synthesis is rapidly occurring.

S Stage: Chromosomes replicated in the nucleus; Chromosomes divide to form identical sister chromatids connected by a centromere.

G2: Chromosomes begin to shorten and coil, and protein synthesis is in high gear; In animals, the centriole pair replicates and prepares to form mitotic spindle

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Mitosis: A period of nuclear Mitosis: A period of nuclear divisiondivision

The process by which two daughter cells are The process by which two daughter cells are formed, each containing a complete set of formed, each containing a complete set of chromosomes.chromosomes.

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MitosisMitosis

ProphaseProphaseMetaphaseMetaphaseAnaphaseAnaphaseTelophaseTelophase

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ProphaseProphase11stst / longest phase of mitosis. / longest phase of mitosis. Chromatin coils up-chromosomes.Chromatin coils up-chromosomes.Two halves of the double structure are called Two halves of the double structure are called

sister chromatids. sister chromatids. (Exact Copies of each (Exact Copies of each other)other)

CentromereCentromere—holds together sister —holds together sister chromatids.chromatids.

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Prophase continued…Prophase continued…

Nucleus disappears Nucleus disappears Nuclear envelope and nucleolus disintegrate.Nuclear envelope and nucleolus disintegrate.Animals—centrioles migrate to opposite end Animals—centrioles migrate to opposite end

of the cell.of the cell.CentrioleCentriole—Small, dark, cylindrical structures —Small, dark, cylindrical structures

that are made of microtubules and are that are made of microtubules and are located just outside the nucleus.located just outside the nucleus.

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Prophase continued…Prophase continued…

SpindleSpindle—A football shaped, cage-like —A football shaped, cage-like structure consisting of thin fibers made of structure consisting of thin fibers made of microtubules.microtubules.

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Metaphase: Second stage of Metaphase: Second stage of mitosismitosis

Chromosomes Chromosomes – Attach to the spindle fibers via centromeres.Attach to the spindle fibers via centromeres.– Pulled by spindle fibers and line up on the midline Pulled by spindle fibers and line up on the midline

(equator).(equator). One sister chromatid’s spindle fiber extends to one One sister chromatid’s spindle fiber extends to one

pole, and the other extends to the opposite poles pole, and the other extends to the opposite poles (ensures a complete set of chromosomes)(ensures a complete set of chromosomes)

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Anaphase: Third Phase of MitosisAnaphase: Third Phase of Mitosis

Separation of sister chromosomesSeparation of sister chromosomes– Centromeres split apart and chromatid pair Centromeres split apart and chromatid pair

separateseparate– Pulled apart by the shortening of the Pulled apart by the shortening of the

microtubules in the spindle fiber.microtubules in the spindle fiber.

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Telophase: 4Telophase: 4thth phase of mitosis phase of mitosisChromosomes reach opposite poles of cell.Chromosomes reach opposite poles of cell.Prophase changes are reversed Prophase changes are reversed

(independent existence).(independent existence).Chromosomes unwind; Spindle breaks down; Chromosomes unwind; Spindle breaks down;

nucleolus reappears; new nuclear envelope nucleolus reappears; new nuclear envelope forms each set of chromosomes; new double forms each set of chromosomes; new double membrane begins to form.membrane begins to form.

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CytokinesisCytokinesis

Cytoplasm divisionCytoplasm division Animal Cells—towards the end of telophase the Animal Cells—towards the end of telophase the

plasma membrane pinches in along the equator plasma membrane pinches in along the equator

Plant Cells—plants have rigid cell wall, so cell plate Plant Cells—plants have rigid cell wall, so cell plate is laid down across cell’s equator. Cell membrane is laid down across cell’s equator. Cell membrane forms around each cell, and new cell walls form on forms around each cell, and new cell walls form on each side of the cell plate until separation is each side of the cell plate until separation is complete.complete.

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Result of MitosisResult of Mitosis Two new cells with chromosome Two new cells with chromosome

sets identical to those of the sets identical to those of the parents; Carry out same function of parents; Carry out same function of parent cells; Grow and divide like parent cells; Grow and divide like parent cells.parent cells.

TissuesTissues: group of cells that work : group of cells that work together to do a specific function.together to do a specific function.

OrgansOrgans: group of two or more : group of two or more tissues organized to perform tissues organized to perform complex activities within an complex activities within an organism.organism.

Organ SystemsOrgan Systems: Multiple organs : Multiple organs that work together to perform that work together to perform specific life function.specific life function.

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Cell CycleCell Cycle

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Control of Cell CycleControl of Cell Cycle

Cell cycleCell cycle 24 to 48 hours 24 to 48 hours less then an hour less then an hour never divide only maturenever divide only mature

A mistake in the cell cycle can A mistake in the cell cycle can lead to cancer.lead to cancer.

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Control of the Cell CycleControl of the Cell Cycle

Enzymes Enzymes – Begin and drive the cell cycle Begin and drive the cell cycle – Control the cycle through its phases.Control the cycle through its phases.

Cell can lose control (Cell can lose control (uncontrolled uncontrolled dividing) dividing) – failure to produce certain enzymesfailure to produce certain enzymes– production of other enzymes at the wrong time.production of other enzymes at the wrong time.

Cancer is the result of uncontrolled cell Cancer is the result of uncontrolled cell division.division.

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Causes of loss of control of cell Causes of loss of control of cell cyclecycle

Environmental FactorsEnvironmental FactorsChanges in enzyme productionChanges in enzyme production

– Enzyme production is directed by genes located Enzyme production is directed by genes located on the chromosome. on the chromosome.

– A A genegene is a segment of DNA that controls the is a segment of DNA that controls the production of a protein.production of a protein.

Many studies point to portion of interphase Many studies point to portion of interphase just before DNA replication as being a key just before DNA replication as being a key control period.control period.

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Cancer: A mistake in the Cancer: A mistake in the Cell CycleCell Cycle

Expressed as cancer when Expressed as cancer when something prompts the damaged something prompts the damaged

genes into action.genes into action.

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CancerCancer

Cancerous cells form masses of tissue called Cancerous cells form masses of tissue called tumorstumors that deprive normal cells of nutrients. that deprive normal cells of nutrients.

Late Stages: Cancer cells enter the Late Stages: Cancer cells enter the circulatory system and spread throughout the circulatory system and spread throughout the body (body (MetastasisMetastasis), forming new tumors that ), forming new tumors that disrupt the function of organs, organ disrupt the function of organs, organ systems, and ultimately the organism.systems, and ultimately the organism.

                              

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In Cancer Cells •There is no awareness of surroundings. •Cells do not stop dividing when crowded. •Cells do not stop after a set number of divisions. •Cells do not enter a resting state. •Cells divide faster and take less time to complete the cycle.

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Cancer: 2Cancer: 2ndnd Leading Cause of Leading Cause of death in the United Statesdeath in the United States

Environmental and Genetic FactorsEnvironmental and Genetic Factors Cigarette smokeCigarette smoke AirAir Water pollutionWater pollution Exposure to UV RadiationExposure to UV Radiation Viral InfectionsViral Infections MySpace, Facebook and TwitterMySpace, Facebook and Twitter

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Cancer PreventionCancer Prevention

Link between healthy lifestyle and the Link between healthy lifestyle and the incidence of cancer.incidence of cancer.

Diets low in fat and high in fiber.Diets low in fat and high in fiber.Minimal amounts of fat.Minimal amounts of fat.Vitamins and minerals; carotenoids, vitamins Vitamins and minerals; carotenoids, vitamins

A, C, and E and calcium.A, C, and E and calcium.Daily exerciseDaily exerciseNo smokingNo smokingDon’t use MySpace, Don’t use MySpace, Face Book and TwitterFace Book and Twitter

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Surface Area and VolumeSurface Area and Volume

Surface Area: 6 (# of sides) x A x ASurface Area: 6 (# of sides) x A x AVolume: A x A X AVolume: A x A X A

•Cube doubledCube doubled•Outside Grows by 4 xOutside Grows by 4 x•Inside grows by 8 xInside grows by 8 x

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