CELLULAR CELLULAR STRUCTURE AND STRUCTURE AND

FUNCTIONFUNCTION

BIG IDEABIG IDEA Cells are the structural and Cells are the structural and

functional units of all living functional units of all living organisms.organisms.

Cell Discovery and Cell Discovery and TheoryTheory

Section 7.1Section 7.1

MAIN IDEA #1MAIN IDEA #1 The invention of the The invention of the microscopemicroscope led led

to the to the discoverydiscovery of cellsof cells..

Important DiscoveriesImportant Discoveries Robert Hooke- observed Robert Hooke- observed corkcork with with

the the first microscopefirst microscope and coined the and coined the term term ““cellulaecellulae”” meaning small rooms meaning small rooms

Anton van Leeuwenhoek- first to Anton van Leeuwenhoek- first to observe observe living organismsliving organisms with a with a microscope microscope

Both men led to many Both men led to many scientific scientific discoveriesdiscoveries (scientific revolution) (scientific revolution)

MicroscopesMicroscopes Compound light microscope- uses Compound light microscope- uses

visible lightvisible light and a series of and a series of lenseslenses to create a to create a magnified imagemagnified image..

MicroscopesMicroscopes Electron microscope- uses Electron microscope- uses magnetsmagnets

to to beambeam electronselectrons at thin specimens. at thin specimens. Only Only nonlivingnonliving cells and tissuescells and tissues can be can be

observed with electron microscopesobserved with electron microscopes

Cell TheoryCell Theory One of the fundamental ideas of One of the fundamental ideas of modern modern

biologybiology and includes the following and includes the following three three principlesprinciples. .

1.1. All living organisms are composed of All living organisms are composed of one one or more cellsor more cells

2.2. Cells are the Cells are the basic unitbasic unit of structure and of structure and organization of all organization of all livingliving organismsorganisms

3.3. Cells arise only from Cells arise only from previously existingpreviously existing cells, with cells cells, with cells passingpassing copiescopies of their of their genetic materialgenetic material on to their daughter cells on to their daughter cells

Cell typesCell types Prokaryotic- cells Prokaryotic- cells withoutwithout a a nucleusnucleus

OROR membrane bound membrane bound organellesorganelles ((mostly unicellularmostly unicellular).).

Eukaryotic- have a Eukaryotic- have a true nucleustrue nucleus and and membrane bound membrane bound organellesorganelles..

Both have plasma membranes!Both have plasma membranes!

Eukaryotic structuresEukaryotic structures Nucleus- distinct Nucleus- distinct central organellecentral organelle

that contains the cellthat contains the cell’’s s genetic genetic materialmaterial in the form of in the form of DNADNA. .

Organelles- enable Organelles- enable specialized cell specialized cell functionsfunctions to take place in different to take place in different parts of the cell at the same time.parts of the cell at the same time.

EukaryotesEukaryotes are thought to have are thought to have evolvedevolved from prokaryotes-from prokaryotes- Endosymbiont TheoryEndosymbiont Theory

The Plasma MembraneThe Plasma Membrane Section 7.2Section 7.2

MAIN IDEA #2MAIN IDEA #2 The The plasma membraneplasma membrane helps to helps to

maintainmaintain a cell a cell’’s s homeostasishomeostasis..

Functions of the Plasma Functions of the Plasma MembraneMembrane

Creates a Creates a thin, flexiblethin, flexible boundaryboundary that that controls controls the the movementmovement of of substances substances into and outinto and out of the cell of the cell

Selective permeability-Selective permeability- capability to capability to allow some substances pass through allow some substances pass through while keeping others out.while keeping others out.

Plasma MembranePlasma Membrane Phospholipid bilayer- phospholipids are Phospholipid bilayer- phospholipids are

arranged in a arranged in a double layerdouble layer, , TAIL TO TAIL TO TAILTAIL..

Phospholipids have a Phospholipids have a polarpolar headhead and and two non-polar two non-polar ““tails.tails.””

Creates the Creates the barrierbarrier that is that is polarpolar at its at its surfacesurface and and non-polarnon-polar in the in the centercenter..

SeparatesSeparates the the insideinside and and outsideoutside environments of the cell.environments of the cell.

THINK ABOUT IT!!!THINK ABOUT IT!!! How do hydrophobic substances How do hydrophobic substances

cross a plasma membrane?cross a plasma membrane?

Other membrane Other membrane componentscomponents

Transport proteins- Transport proteins- movemove needed needed substancessubstances or wastes or wastes throughthrough the the membrane. membrane.

Cholesterol- non-polar molecule Cholesterol- non-polar molecule among the phospholipidsamong the phospholipids; keeps the ; keeps the ““tailstails”” from sticking together- from sticking together- fluidityfluidity

Carbohydrates (sugars)- help with Carbohydrates (sugars)- help with cell cell identificationidentification

Fluid Mosaic ModelFluid Mosaic Model Phospholipids Phospholipids can movecan move sidewayssideways

across the membraneacross the membrane Other components can even Other components can even move move

through/amongthrough/among the bilayer. the bilayer. The The fluidityfluidity of the membrane of the membrane allowsallows

a a scattered/random patternscattered/random pattern arrangement of the components- arrangement of the components- mosaicmosaic..

Structures and Structures and OrganellesOrganelles

Section 7.3Section 7.3

MAIN IDEA #3MAIN IDEA #3 Eukaryotic cellsEukaryotic cells

contain contain organellesorganelles that allow the that allow the specializationspecialization and and the the separationseparation of of functions within functions within the cell. the cell.

Cytoplasm Cytoplasm semifluidsemifluid environment environment

insideinside the the plasma plasma membrane.membrane.

In In ALL cellsALL cells Prokaryotic- Prokaryotic- allall

chemical chemical processesprocesses Eukaryotic- Eukaryotic- processesprocesses

take place take place inin organellesorganelles

CytoskeletonCytoskeleton FrameworkFramework for the cell for the cell withinwithin the the

cytoplasm cytoplasm also aids in also aids in cell movementcell movement and other cellular activities.and other cellular activities.

ALL EukaryoticALL Eukaryotic cells cells Microtubules- Microtubules- longlong, ,

hollow protein hollow protein cylinderscylinders Microfilaments- Microfilaments- thinthin

protein protein threadsthreads..

Cell StructuresCell Structures Nucleus- Nucleus- control centercontrol center of the cell of the cell

that contains that contains coded directionscoded directions for for the production of the production of proteinsproteins and and cell cell divisiondivision.. Surrounded by a Surrounded by a nuclear envelopenuclear envelope ALL EukaryoticALL Eukaryotic

Cell StructuresCell Structures Ribosomes- site of Ribosomes- site of

protein synthesisprotein synthesis Made of Made of 2 2

componentscomponents Can be Can be free floatingfree floating

OR attachedOR attached to the to the ERER

ManufacturedManufactured byby the the nucleolusnucleolus

ALL cellsALL cells

Cell StructuresCell Structures

Endoplasmic reticulum- highly Endoplasmic reticulum- highly folded membranefolded membrane that is the site of that is the site of protein and lipid synthesisprotein and lipid synthesis ALL EukaryoticALL Eukaryotic Smooth- does Smooth- does NOTNOT have have ribosomesribosomes attached attached Rough- Rough- HAS ribosomesHAS ribosomes associated within associated within

Cell StructuresCell Structures Golgi apparatus- a Golgi apparatus- a flattened stackflattened stack of of

tubular membranestubular membranes that that modifiesmodifies proteins proteins and and packagespackages them them for for distributiondistribution outside the cell outside the cell

ALL EukaryoticALL Eukaryotic Vesicles= packagesVesicles= packages; fuses with plasma ; fuses with plasma

membranemembrane

Cell StructuresCell Structures Vacuoles- a membrane- bound Vacuoles- a membrane- bound

vesicle for the temporary vesicle for the temporary storagestorage of of materialsmaterials Plant cells- Plant cells- ONE largeONE large Animal cells- a Animal cells- a FEW smallFEW small

Cell StructuresCell Structures Lysosomes- a Lysosomes- a

vesiclevesicle that that contains contains digestive digestive enzymesenzymes for the for the breakdownbreakdown of of excess or worn-out excess or worn-out cellular cellular substancessubstances.. Animal cells ONLYAnimal cells ONLY

Cell StructuresCell Structures Centrioles- organelles that Centrioles- organelles that occur in occur in

pairspairs and are important for and are important for cell cell divisiondivision Animal cellsAnimal cells MOST protistMOST protist

Cell StructuresCell Structures Mitochondria- a membrane-bound Mitochondria- a membrane-bound

organelle that organelle that makes energymakes energy available to the rest of the cell. available to the rest of the cell. ALL Eukaryotic cellsALL Eukaryotic cells

Cell StructuresCell Structures Chloroplasts- a Chloroplasts- a

double-membrane double-membrane organelle with organelle with thylakoidsthylakoids containing containing chlorophyllchlorophyll where where photosynthesisphotosynthesis takes place. takes place. Plant cells ONLYPlant cells ONLY

Cell StructuresCell Structures Cell wall- an Cell wall- an inflexibleinflexible barrierbarrier that that

provides provides support and protectssupport and protects the the plant cell. plant cell. Plant cellsPlant cells Fungi cellsFungi cells SOME ProkaryotesSOME Prokaryotes

Cell StructuresCell Structures Cilia and flagella- Cilia and flagella- projectionsprojections from from

cell surfaces that aid in cell surfaces that aid in locomotionlocomotion and and feeding.feeding. Cilia- Cilia- tiny hairstiny hairs; SOME animal cells, ; SOME animal cells,

protists cells, and Prokaryotesprotists cells, and Prokaryotes Flagella- Flagella- tail liketail like; SOME animal cells, ; SOME animal cells,

Prokaryotes, and some plant cellsProkaryotes, and some plant cells

Cellular TransportCellular Transport Section 7.4Section 7.4

MAIN IDEA #4MAIN IDEA #4 Cellular transportCellular transport

moves substancesmoves substances WITHINWITHIN the cell the cell and moves and moves substances substances INTO INTO & OUT& OUT of the cell. of the cell.

DiffusionDiffusion The The netnet movementmovement of particles from of particles from

an area of an area of high concentration to low high concentration to low concentrationconcentration..

Dynamic equilibrium- condition, in Dynamic equilibrium- condition, in which there is which there is continuous movementcontinuous movement but but NO overall changeNO overall change

DiffusionDiffusion Factors that Factors that affectaffect diffusion diffusion raterate

ConcentrationConcentration TemperatureTemperature PressurePressureEx: Ex: more collision= faster diffusionmore collision= faster diffusion

Diffusion does NOT require any Diffusion does NOT require any energy!energy!

Facilitated DiffusionFacilitated Diffusion Uses Uses transport proteinstransport proteins to to movemove

other other ionsions and and small moleculessmall molecules across the plasma membrane. across the plasma membrane.

Still from Still from high concentration to low high concentration to low concentration!concentration!

OsmosisOsmosis

DiffusionDiffusion of of waterwater across a across a selectively selectively permeable membrane. permeable membrane.

Also exhibits Also exhibits dynamic equilibriumdynamic equilibrium

IsotonicIsotonic Cell is in a solution Cell is in a solution

that has the that has the same same concentrationconcentration of of water and solutes.water and solutes.

Stable/EquilibriumStable/Equilibrium

Hypotonic Hypotonic Cell is in a solution that has a Cell is in a solution that has a lower lower

concentrationconcentration of of solutesolute.. Net movementNet movement of water of water INTOINTO the cell the cell

HypertonicHypertonic The The concentrationconcentration

of the of the solutesolute outside of the cell outside of the cell is is higherhigher than than inside.inside.

Net movementNet movement of of water is water is OUTOUT of of the cellthe cell

Active TransportActive Transport The The net movementnet movement of particles of particles

againstagainst a a concentration gradientconcentration gradient.. Requires energyRequires energy Maintains homeostasisMaintains homeostasis

Na+/K+ PumpNa+/K+ Pump Uses Uses ATP energyATP energy

to transport to transport three three sodiumsodium ions ions outout of of the cell while the cell while moving moving two two potassiumpotassium ions ions intointo the cell. the cell.

++++++

Large ParticlesLarge Particles Endocytosis- Endocytosis- intakeintake of a substance of a substance Exocytosis- Exocytosis- secretionsecretion of a substance of a substance