Cell TheoryCell TheoryCellsCells are the basic living units of organization and function

All cells come from other cellscome from other cellsWork of Schleiden, Schwann, Schleiden, Schwann, and Virchowand Virchow contributed to this theory

Each cell is a microcosm of life

Biological Size and Cell Biological Size and Cell DiversityDiversity

Cell surface area-to-volume surface area-to-volume ratioPlasma membrane Plasma membrane must be large enough relative to cell volume to regulate passage of materials

Volume increases faster than surface area so cells must must dividedivide

Cell size and shape related to size and shape related to functionfunction

Cell Surface Area-to-Volume Cell Surface Area-to-Volume RatioRatio

MicroscopesLight microscopeLight microscope, referred to as compoundcompound microscope, used by most students

Two features determine how clearly an object is viewedMagnificationMagnificationResolutionResolution

Light microscope has 500 times more resolution than human eye

Electron microscopeDeveloped in the 1950sAllows study of the ultrastructure of cells

10,000 times more resolution than human eye

Types of electron microscopeTransmission electron microscope TEMTEM

Used to view internal cell structuresinternal cell structuresScanning electron microscope SEMSEM

Produces 3-D picture of cell surface3-D picture of cell surfaceCan’tCan’t be used to view living cellsview living cells

Comparing light and electron microscopy

Cell fractionationCell fractionationUsed to determine isolate & tell function of organelles

Cells broken apart and the resulting cell extract spun in a centrifuge

Centrifugal force separates extractPelletPellet – heavier cell organellesSupernatant Supernatant – liquid poured off

Cell fractionation

ProkaryoticProkaryoticBacteria and Archaea (ancient bacteria)

DNA not enclosed in a nucleusEukaryotic

All other known organismsHighly organized membrane-enclosed organellesCytoplasmNucleoplasm

Functions of cell or plasma membranesDivide cell into compartmentsDivide cell into compartments, allowing for specialized activities

Interacting membranes form endomembrane systemendomembrane system

VesiclesVesicles transport materials between compartments (ER Golgi, Golgi plasma membrane…)

DiagraDiagram ofm of

a plant a plant cellcell

DiagraDiagram ofm ofan an

animal animal cellcell

The cell nucleuscell nucleusContains DNADNABounded by

Nuclear envelopeNuclear envelopeDoubleDouble membrane perforated with nuclear poresnuclear pores

DNA forms chromatinchromatin, which is organized into chromosomes

NucleolusNucleolusRNARNA synthesis and ribosomeribosome assembly

The cellThe cellnucleusnucleus

Endoplasmic reticulum (ER)Network of folded internal membranes in the cytosol

Connected to Nuclear envelopeNuclear envelopeSmooth ER Smooth ER

Site of lipid synthesislipid synthesisSite of detoxifying enzymesdetoxifying enzymesDetoxifies drugs & alcoholDetoxifies drugs & alcoholStores Ca++ in muscle cellsStores Ca++ in muscle cells

Rough ERRough ERRibosomes on surface manufacture

secretory proteinssecretory proteinsProteins may be moved into the ER

lumen (interior)

EndoplasEndoplasmicmic

reticulum reticulum (ER)(ER)

Golgi complexCisternaeCisternae that process, sort, and modify proteins

In animal cellsanimal cells, Golgi complex also manufactures lysosomes lysosomes

GlycoproteinsGlycoproteinsTransported to the ciscis face (receiving side)

Golgi modifies modifies carbohydrates and lipids and packages into packages into vesiclesvesicles that pinch off the pinch off the trans face trans face (shipping side)

Golgi complex

LysosomesLysosomes break down worn-out cell structures, bacteria, and other substances

Responsible for cell death & cell death & recyclingrecycling

PeroxisomePeroxisomessInvolved in lipid metabolism lipid metabolism and detoxification

Contain enzymes (catalasecatalase) that produce and degrade hydrogen hydrogen peroxide peroxide HH22OO22 H H22O + OO + O22

Lysosomes

Mitochondria Mitochondria Sites of aerobic respirationaerobic respirationOrganelles enclosed by a double membrane

Has its own genome own genomePlace important role in apoptosisapoptosisCristaeCristae (internal folds) and matrix matrix (innermost space) contain enzymes for aerobic respirationNutrients broken down and energy packaged in ATPATP

Carbon dioxide Carbon dioxide and water water by-products

Mitochondria

ChloroplastsChloroplasts PlastidsPlastids that carry out photosynthesisphotosynthesis

Inner membrane of chloroplast encloses the stroma gel-like liquid)stroma gel-like liquid)

Contains stacks of interconnectedinterconnected sacs called thylakoids thylakoids

Stack of thylakoids called granagranaDuring photosynthesis, chlorophyll traps light energy light energy (sunlight)

Energy converted to chemical chemical energy in ATPenergy in ATP

Chloroplast

Cellular respiration and photosynthesis

CytoskeletonCytoskeleton Internal framework made of

Microtubules - tubulinMicrotubules - tubulinMicrofilaments - actinMicrofilaments - actinIntermediate filaments - keratinIntermediate filaments - keratin

Provides structural supportstructural supportInvolved with transport of materials in the cell

Make up cilia, flagella, and cilia, flagella, and centriolescentrioles

TheCytoskelet

on

Cilia and flagella Cilia and flagella Thin, movable structures that project from cell surface

Function in movementMicrotublesMicrotubles anchored in cell by basal bodybasal body

Structureof cilia

GlycocalyxGlycocalyx Cell coat formed by polysaccarides extending from plasma membrane

Many animal cells also surrounded by an extracellular matrix (ECM)extracellular matrix (ECM)

Most bacteria, fungi, and plant cell walls made of carbohydrates

Extracellular matrix

Plantcell walls