Cytology

CytologyCytologyThe Study of CellsThe Study of Cells

ThemesThemes Emergent propertiesEmergent properties: interactions : interactions

among cell components produces ‘life’among cell components produces ‘life’ Structure and functionStructure and function: cell : cell

processes based upon ordered processes based upon ordered structuresstructures

InteractionsInteractions: exchange and respond to : exchange and respond to external environmentexternal environment

EvolutionEvolution: adaptations of structure: adaptations of structure

Relative sizes

How Cells Are StudiedHow Cells Are Studied MicroscopeMicroscope: : # 1 tool# 1 tool

1665 Robert Hooke; “Cells”1665 Robert Hooke; “Cells” MagnificationMagnification = how much larger = how much larger

object is made to appearobject is made to appear ResolutionResolution = minimum distance = minimum distance

between 2 points that can still be seen between 2 points that can still be seen as 2 points; ‘focused’as 2 points; ‘focused’

How Cells Are StudiedHow Cells Are Studied

Two types of microscopes:Two types of microscopes: LightLight: 1500x; light passes through : 1500x; light passes through

lenslens Electron MicroscopeElectron Microscope: electrons : electrons

instead of light waves (smaller) instead of light waves (smaller) electromagnets aim electron beamelectromagnets aim electron beam

How Cells Are StudiedHow Cells Are Studied 3 types of electron microscopes:3 types of electron microscopes:

Transmission Electron Microscope; Transmission Electron Microscope; TEM; TEM; electrons pass through subject, electrons pass through subject, 100,000x100,000x

Scanning Electron Microscope; Scanning Electron Microscope; SEM; electrons bounce off a thin gold SEM; electrons bounce off a thin gold plate on the surface of the object; plate on the surface of the object; 60,000x; 3d60,000x; 3d

Scanning-tunneling STM; 1,000,000 xScanning-tunneling STM; 1,000,000 x

TEM SEM

How Cells Are StudiedHow Cells Are Studied Cell FractionationCell Fractionation:: Disrupt cell; centrifuge Disrupt cell; centrifuge

organelles to the bottomorganelles to the bottom ‘‘Pellet’Pellet’

Separate and isolate pelletsSeparate and isolate pellets Study function Study function

independentlyindependently

Panoramic View of the Panoramic View of the CellCell

ProkaryoteProkaryote BacteriaBacteria No nucleus No nucleus

(nucleoid)(nucleoid) No membrane-No membrane-

bound organellesbound organelles Ribosomes Ribosomes

EukaryoteEukaryote Animal, plants, Animal, plants,

fungi, protistsfungi, protists Nucleus (DNA)Nucleus (DNA) Membrane-bound Membrane-bound

organellesorganelles

Eukaryotic CellsEukaryotic Cells Cell membraneCell membrane CytoplasmCytoplasm = region (matrix) between cell = region (matrix) between cell

membrane and nucleusmembrane and nucleus CytosolCytosol = semi-fluid medium in the = semi-fluid medium in the

cytoplasmcytoplasm

Eukaryotic CellsEukaryotic Cells EukaryotesEukaryotes more complex than more complex than

prokaryotesprokaryotes More DNAMore DNA More organellesMore organelles Enables larger size due to more efficient Enables larger size due to more efficient

metabolism (specialized organelles)metabolism (specialized organelles)

Size of CellsSize of Cells Limited by surface area /volume ratioLimited by surface area /volume ratio

-Volume increases 8 x faster than S.A.-Volume increases 8 x faster than S.A.

- Problems with diffusion- Problems with diffusion Limited by the amount of DNALimited by the amount of DNA

DNA must be able to keep up with DNA must be able to keep up with demands of the cytosoldemands of the cytosol

Eukaryotic CellsEukaryotic Cells

CompartmentalizationCompartmentalization:: Eukaryotic cells have 1000x the volume Eukaryotic cells have 1000x the volume

of prokaryotic cellsof prokaryotic cells Need way to process cell activitiesNeed way to process cell activities How can you create more area?How can you create more area?

Internal membranes!!!!Internal membranes!!!!

Increase surface area;Increase surface area; Specialized molecules are embedded Specialized molecules are embedded

within so they can carry on some within so they can carry on some metabolism; (chemiosmosis)metabolism; (chemiosmosis)

Partitions create compartments to isolate Partitions create compartments to isolate chemical reactionschemical reactions

Structure and functionStructure and function

NucleusNucleusNucleusNucleus Nucleus:Nucleus: 2 parts:2 parts:

DNADNA Nuclear envelopeNuclear envelope

NucleusNucleus Nuclear envelope:Nuclear envelope:

Phospholipid bilayerPhospholipid bilayer PoresPores

MostMost of the genes of the genes Mitochondria, chloroplastsMitochondria, chloroplasts

NucleusNucleus

DNA:DNA: ChromatinChromatin = DNA wrapped = DNA wrapped

around protein (histone)around protein (histone) ChromosomesChromosomes = coiled, = coiled,

condensed chromatincondensed chromatin GenesGenes = sections of DNA that code = sections of DNA that code

for proteinsfor proteins

NucleusNucleus NucleolusNucleolus: : large, obvious structure in large, obvious structure in

non-dividingnon-dividing cells cells Composed of Composed of ribosomesribosomes in production in production May have 2 or more per cellMay have 2 or more per cell

NucleusNucleus Protein synthesisProtein synthesis::

mRNA transcribed in NucleusmRNA transcribed in Nucleus Through nuclear pores into cytoplasmThrough nuclear pores into cytoplasm Attaches to ribosomes to be translated Attaches to ribosomes to be translated

into amino acid sequences (primary into amino acid sequences (primary structure)structure)

RibosomesRibosomesRibosomesRibosomes

Protein synthesisProtein synthesis Non-membrane bound (prokaryotes)Non-membrane bound (prokaryotes) Prokaryotes have slightly different Prokaryotes have slightly different

ribosome molecular structure (antibiotics ribosome molecular structure (antibiotics tetracycline, streptomycin)tetracycline, streptomycin)

Protein synthesisProtein synthesis Non-membrane bound (prokaryotes)Non-membrane bound (prokaryotes) Prokaryotes have slightly different Prokaryotes have slightly different

ribosome molecular structure (antibiotics ribosome molecular structure (antibiotics tetracycline, streptomycin)tetracycline, streptomycin)

RibosomRibosomesesRibosomRibosomeses

Free ribosomesFree ribosomes; float in cytosol; float in cytosol; ; proteins within proteins within the cell; musclethe cell; muscle

Bound ribosomesBound ribosomes ((ER); proteins for secretion; ER); proteins for secretion; pancreas, liver, etcpancreas, liver, etc

Endomembrane SystemEndomembrane System Vesicles Vesicles Nuclear envelopeNuclear envelope Endoplasmic reticulumEndoplasmic reticulum GolgiGolgi LysosomesLysosomes VacuolesVacuoles Plasma membranePlasma membrane

Endomembrane SystemEndomembrane SystemEndomembrane SystemEndomembrane System

Membranes vary in structure and Membranes vary in structure and functionfunction

Dynamic; constantly changing in Dynamic; constantly changing in composition, behavior, and thicknesscomposition, behavior, and thickness

Endomembrane SystemEndomembrane SystemEndomembrane SystemEndomembrane System

VesiclesVesicles = membrane-enclosed sacs = membrane-enclosed sacs that are pinched off portions of that are pinched off portions of membranes moving from one membranes moving from one membrane to anothermembrane to another

Endomembrane SystemEndomembrane System

Endoplasmic reticulum (ER)Endoplasmic reticulum (ER) Endo = within; reticulum = networkEndo = within; reticulum = network

Network of tubules and sacs Network of tubules and sacs (cisternae)(cisternae)

Creates passages, chemical Creates passages, chemical ‘laboratories’ ‘laboratories’

Continuous with outer nuclear Continuous with outer nuclear membranemembrane

Endoplasmic ReticulumEndoplasmic Reticulum

22 types: types: SmoothSmooth andand RoughRough SmoothSmooth - - Makes lipids,Makes lipids, steroidssteroids

phospholipids; adrenal glands; phospholipids; adrenal glands; gonads, skin oil glandsgonads, skin oil glands

Carbohydrate metabolismCarbohydrate metabolism; liver, ; liver, enzyme converts glycogen into enzyme converts glycogen into glucoseglucose

Detoxifies poisons/drugsDetoxifies poisons/drugs: adds OH : adds OH Store CaStore Ca for muscle contraction for muscle contraction


Rough ERRough ER: make proteins: make proteins


GolgiGolgi = = stacked, flattened discs; sacs stacked, flattened discs; sacs (cisternae)(cisternae)

Stores, modifies and routes products Stores, modifies and routes products from ERfrom ER

Enzymes modify products of EREnzymes modify products of ER Manufactures some macromolecules Manufactures some macromolecules

(pectins)(pectins) Sorts products for secretionSorts products for secretion

Endomembrane SystemEndomembrane System LysosomesLysosomes = = membrane-bound membrane-bound

organelle with hydrolytic enzymesorganelle with hydrolytic enzymes Lipases, carbohydrases, proteases, Lipases, carbohydrases, proteases,

nucleasesnucleases Intracellular digestionIntracellular digestion - -

phagocytosis; phagocytosis; AmoebaAmoeba, macrophages, macrophages

RecycleRecycle - worn out organelles - worn out organelles RemodelingRemodeling - metamorphosis - metamorphosis

Lysosome formation


Vacuoles:Vacuoles: membrane-bound sac, membrane-bound sac, larger than a vesiclelarger than a vesicle

2 types and functions:2 types and functions: Food vacuoleFood vacuole: phagocytosis; : phagocytosis;

intracellular digestionintracellular digestion Water vacuolesWater vacuoles – store water – store water

and excrete waterand excrete water

Endomembrane Endomembrane SystemSystem

Contractile vacuoleContractile vacuole; ; fresh-water protozoa fresh-water protozoa (paramecium) (paramecium)

Excretes excess water Excretes excess water out; osmosisout; osmosis

Central VacuoleCentral Vacuole Large vacuole found in Large vacuole found in

plant cellsplant cells TonoplastTonoplast;; membrane membrane

around vacuolearound vacuole Storage - minerals, Storage - minerals,

water (turgor water (turgor pressure), poisonspressure), poisons

Helps provide shape, Helps provide shape, rigidity in plant cellsrigidity in plant cells

Other Membranous Other Membranous OrganellesOrganelles

Mitochondria and chloroplastsMitochondria and chloroplasts PeroxisomesPeroxisomes

Energy TransducersEnergy Transducers MitochondriaMitochondria and and ChloroplastsChloroplasts Double layer membraneDouble layer membrane Not part of endomembraneNot part of endomembrane Contain DNA and ribosomesContain DNA and ribosomes

Semiautonomous; grow and Semiautonomous; grow and reproduce in cells on their ownreproduce in cells on their own

MitochondriaMitochondria Sites of cellular aerobic respiration Sites of cellular aerobic respiration Found in nearly all eukaryotic cellsFound in nearly all eukaryotic cells Number of depends upon metabolic Number of depends upon metabolic

activity and cell typeactivity and cell type

MitochondriaMitochondria

MatrixMatrix: : enclosed by inner enclosed by inner membrane; Kreb’smembrane; Kreb’s

CristaeCristae; embedded ; embedded cytochromes for ETCcytochromes for ETC

Intermembrane spaceIntermembrane space: : proton gradientproton gradient

ChloroplastsChloroplasts Plastids: plant cellsPlastids: plant cells Amyloplast:Amyloplast: store starchstore starch Chromoplast:Chromoplast: store pigments; store pigments;

chromo = ‘color’; flowerschromo = ‘color’; flowers ChloroplastChloroplast - - chloro = ‘green’chloro = ‘green’

ChloroplaChloroplastst

ThylakoidThylakoid:: folded folded membranemembrane

GranaGrana:: stacks of stacks of thylakoidthylakoid

Intermembrane Intermembrane spacespace

StromaStroma:: matrix of matrix of chloroplastchloroplast

PeroxisomesPeroxisomes Organelles with ‘teams’ of Organelles with ‘teams’ of

enzymes for specific metabolic enzymes for specific metabolic pathways; produce peroxidepathways; produce peroxide

CatalaseCatalase = enzyme that catalzyes = enzyme that catalzyes hydrogen peroxide into water and hydrogen peroxide into water and oxygenoxygen

Fats and alcohol; seed Fats and alcohol; seed germinationgermination

CytoskeletonCytoskeleton Network of protein fibers within Network of protein fibers within

cytosolcytosol Function:Function:

FrameworkFramework SupportSupport Movement Movement

Cilia/flagellaCilia/flagellaMitotic spindleMitotic spindle

Framework

MotilityMotility: motor molecules

CytoskeletonCytoskeleton 3 parts: 3 parts: MicrotubulesMicrotubules MicrofilamentsMicrofilaments Intermediate Intermediate

filamentsfilaments

MicrotubulesMicrotubules Straight, hollow fibers (tubulin)Straight, hollow fibers (tubulin) Support, cell shapeSupport, cell shape Organelle movement; motor Organelle movement; motor

moleculesmolecules Spindle; during mitosisSpindle; during mitosis

Move chromosomesMove chromosomes

MicrotubulesMicrotubules Centrioles: animal

cells only Plants have

centrosomes (MTOC) Centrioles =

cylindrical structures outside the nucleus; replicate during prophase; grow spindle between

MicrotubulesMicrotubules CiliaCilia; ; short, hairlike, oarlike short, hairlike, oarlike

movement (perpendicular to action)movement (perpendicular to action) FlagellaFlagella: : long; few or one; long; few or one;

undulate; movement parallel to undulate; movement parallel to directiondirection

Cilia/FlagellaCilia/Flagella Structure: Structure: Microtubule core Microtubule core (9+2 (9+2

arrangement);arrangement); ATP needed ATP needed Basal bodyBasal body = anchors cilia/flagella = anchors cilia/flagella

into cellinto cell

MicrofilamentMicrofilament Actin filamentsActin filaments Smallest of cytoskeleton structureSmallest of cytoskeleton structure Globular actin (protein) wound in a helixGlobular actin (protein) wound in a helix Muscle contraction (along with myosin)Muscle contraction (along with myosin) Cleavage furrows during mitosisCleavage furrows during mitosis Cyclosis; cytoplasmic streaming (plants)Cyclosis; cytoplasmic streaming (plants) Elongation of pseudopodia in amoeba; Elongation of pseudopodia in amoeba;

macrophagesmacrophages

Macrophage

Intermediate FibersIntermediate Fibers

Between microtubules and Between microtubules and microfilaments in sizemicrofilaments in size

Tension (structure) framework (?) Tension (structure) framework (?) for cytoskeletonfor cytoskeleton

NOT disassembled, reassembled NOT disassembled, reassembled frequentlyfrequently

Cell Surface: Cell Surface: PlantsPlants

Plant cellsPlant cells: cell walls composed of : cell walls composed of cellulose within a matrix of cellulose within a matrix of polysaccharides and proteinpolysaccharides and protein Fungi – chitinFungi – chitin Bacteria - peptidoglycansBacteria - peptidoglycans

Primary Cell wallPrimary Cell wall = = between two between two plant cellsplant cells


Middle lamellaMiddle lamella = sticky pectins = sticky pectins (polysaccharides); ‘glues’ cells (polysaccharides); ‘glues’ cells together together

Secondary cell wallSecondary cell wall = between the = between the membrane and primary cell wallmembrane and primary cell wall

Cell Surface: Cell Surface: AnimalsAnimals GlycocalyxGlycocalyx = (‘sweet husk’) sticky = (‘sweet husk’) sticky

oligosaccharides (‘few’); ‘glues’ cells oligosaccharides (‘few’); ‘glues’ cells together, stick to lipids, proteins of together, stick to lipids, proteins of adjacent cells.adjacent cells.

Strength, identification with other Strength, identification with other cellscells

Intercellular JunctionsIntercellular Junctions

Joints between cells (tissue Joints between cells (tissue formation)formation)

PlantsPlants = = PlasmodesmataPlasmodesmata AnimalsAnimals = tight junctions, = tight junctions,

desmosomes, gap junctions; desmosomes, gap junctions;


PlasmodesmataPlasmodesmata = linking channels = linking channels between two plant cellsbetween two plant cells

Cell-to-cell communication; one solid Cell-to-cell communication; one solid organismorganism

Animal Cell JunctionsAnimal Cell Junctions

Tight junctionsTight junctions = = cells closely cells closely ‘knit’ together; block intercellular ‘knit’ together; block intercellular junctions; prevents intercellular fluid junctions; prevents intercellular fluid loss (brain block, tubular leakage)loss (brain block, tubular leakage)

Cells are ‘fused’ togetherCells are ‘fused’ together


DesmosomesDesmosomes =(‘binding body’) =(‘binding body’) intercellular junctions that are tight intercellular junctions that are tight but allow some substances to ‘leak’but allow some substances to ‘leak’

Strengthen linkages between cellsStrengthen linkages between cells Also called anchoring junctionsAlso called anchoring junctions

Anchoring junctions


Gap junctionsGap junctions = channels = channels between cells; allows some between cells; allows some substances to pass through, substances to pass through, especially in tissues that need to especially in tissues that need to communicatecommunicate

Heart muscle cells, stem cellsHeart muscle cells, stem cells

Gap junctions

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Cytology