TheMicroscope

Operatethecompoundlightmicroscope

MicroscopeTheory

• Magnificationistheenlargementofanimage• Theminimumresolveddistanceistheminimumdistanceatwhichtwoobjectsorimagescanbe

identifiedasdistinctfromeachother• Thesystemoflensesinthecondensercontrolsthefocusofthelightbymovingupanddown• Whentheconeoflightjustfillsthelensoftheobjective,maximumresolvingpowerisobtained• Theamountoflightreachingtheobjectiveiscontrolledbytheirisdiaphragm• Whentheangularapertureofthecondenseririsdiaphragmistoonarrow,thefieldofviewwillbetoo

dark,theresolutionpoor,andthecontrasttoohigh• Thecontrolonthelightsourcecontrolstheintensityofthelight• Theimageseenthroughtheeyepieceisinvertedandmagnified

Applyascaletoyourdrawings• Ascaleisusedsotherepresentationcanberelatedtothesizeofthespecimenratherthana

magnificationasitdistortsthephoto

Estimatethesizeofmicroscopicobjects• Whenthediameterofthefieldofviewofanobjectivelensisknown,theapproximatesizeofanobject

viewedonaslidecanbedeterminedbyestimatingthenumberoftimestheobjectfitsacrossthediameterofthefieldofview

1.CellStructure

Describethestructuresandfunctionsofa(eukaryotic–membrane-bound)animalcellOrganelle FunctionNucleus Directscell’slifeprocesses,containsthechromosomesandDNA

Nuclearmembrane Separatesthenucleusfromthecytoplasm.Controlsthehighly-selectivetwo-wayexchangebetweenthenucleusandcytoplasm(vianuclearpores)

Nucleolus DenseareainthenucleuswhichcontainsgenesthatsynthesiseribosomalRNAwhichiscombinedwithproteins

Cytoplasm(cytosol) Semi-fluidmaterialinwhichtheorganellesarefoundCellmembrane(plasmamembrane)

Regulatesmovementofsubstancesintoandoutofthecell(Alsoreferredtoasphospholipidbilayer)Centre:hydrophobic‘waterhating’Outside:hydrophilic‘waterloving’

ProteinchannelsPassive–allowsmovementacrossagradient,hightolowconc.Active–requiresenergytomoveionsacrossthemembrane

Mitochondria

Cellularrespiration(producesATP–energy)

Roughendoplasmicreticulum

Siteofproteinsynthesisandtransport(representedbydotsonsurfacewhichrepresentribosomes)

Smoothendoplasmicreticulum

Siteoflipidsynthesis,proteinmodificationanddetoxifyingpoisons(inliver)

Golgibody Storage,modificationandpackagingofproteins(carbohydrates,lipids,hormones,channelproteins)Secretoryproteinsremovedbyexocytosis

Lysosome(formedbygolgi)

ContainshydrolyticenzymesforcellulardigestionandcelldefenceBreaksdownbacteriabyendocytosis(engulfing)

Ribosome ProteinsynthesisCytoskeleton Microtubules–formtheshapeofthecell(centrioles,ciliaandflagella)

Intermediatefilaments–givestrengthtocell(actin,myosin)Microfilaments–allowabsorptionofnutrients,max.SA(microvilli)

3.Muscles

Describethethreemainmuscletissuetypes SkeletalMuscle CardiacMuscle SmoothMuscleLocation Attachedtobones Intheheart Inthewallsofholloworgans,

bloodvessels,eyes,glands,skinCellshape Verylong,cylindricalcells Cylindricalcellsthatbranch Spindle-shapedcellsNucleus Multinucleated,peripherally

locatedSingle,centrallylocated Single,centrallylocated

Striations Yes Yes NoControl Voluntary(conscious) Involuntary(unconscious) Involuntary(unconscious)Abilitytocontractspontaneously

No Yes Yes

Function Movesthebody Providesthemajorforceformovingbloodthroughthebloodvessels

Movesfoodthroughoutdigestivetract,emptiestheurinarybladder,regulatesbloodvesseldiameter,changespupilsize,contractsmanyglandducts

Specialfeatures

None Branchingfibres,intercalateddiskscontaininggapjunctionsjoiningcellstoeachother

Gapjunctions

StatetheslidingfilamenttheoryofmusclecontractionandexplaintheroleofcalciuminmusclecontractionStriatedmuscle

• Movementofboneso Flexionandextension

• Containslotsofnervesandbloodvesselso Reservoirforblood

• Slidingfilamenttheoryo Thickfilamentsaremadeofmyosino Thinfilamentsmadeofactino Sarcomere–themuscleunitthatdoes

theworko Whenthemusclesarerelaxedthe

actinisseparatedattheH-zoneandpulledtogetherwhenmuscleistensed

Neuro-muscularjunction

• Sarcoplasmicreticulumisendoplasmicreticulumforskeletalmuscleo Holdsthecalcium(insolution)

• Nervecellsbringthenervestothemuscle• Neurotransmittersreleasemusclereceptorstoopenupandallowpositivechargestorushintothe

muscle(de-polarisation)o De-polarisation–rapidinfluxofpositivecharges

• Ttubulestransmitschargesallthroughmuscletissuewhichcausessarcoplasmicreticulumtoreleasecalciumwhichcausesmusclecontractions

• Musclemolecules:o Myosin–pullsactin

§ Stemcanbendtograbtheactin§ ATPturnsintoADPfirst§ Gamma-phosphateattachestomyosinandpullthe

myosinheadback,whenthegamma-phosphateisreleased,theheadspringsbackintotheshape,pullingtheactinfilaments

o Actin–doublehelixstructure,blackdotsarebindingsiteformyosinhead

o Tropomyosin–stopsmusclesfromcontractingconstantly§ Wrapsaroundactinbindingsitesandobstructsmyosinbinding

o Troponin–switchthatpullsthetropomyosinawayfromthebindingsite

o Calciumions–triggersthetroponinbybindingtoitandcausingittochangeshape§ Calciumcomesfromtheterminalcisternae

inthesarcoplasmicreticulumo ATP–gamma-phosphateaddedontomyosin

§ Gammacomesoffandputsachargeonmyosinwhichdisruptstheinteractionbetweenaminoacidsthuschangingtheshapeoftheprotein

§ Composedof:ribose-sugar,adenine,phosphateswithnegativelychargedphosphatesattached(alpha,beta,gamma)