CHAPTER8:
cetlstructure
THE CELL - Eukaryotic
Plasmamembrane
. boundary
betweencellandexternal
environment
. controlsmovement
of materialentering
etc.
andexitingthe cell(oxygen,nutrients,
products
andexcesswater
enter waste
leave)
. flexibleandallowscelltovaryits shapeif
needed
P|{rmr i|tmbrrns Bbuctu|rNcomponentt
Howdo thingscrossa cell membrane?
. somematerials
(passive
or active)
enterandleavethroughproteinpassageways
. Othermaterials
passdirectlythroughthe membrane
(passive diffusion)
*** Diffusion
of molecules
froma regionin whichtheyare highly
is the movement
concentrated
to a regionin whichtheyare lessconcentrated
Gellwall
. an additional
in somecells
outsidethe plasmamembrane
externalboundary
.
inflexible
relatively
Phnt Cdl Wsll
.
muchthickerthanthe
. plasmamembrane
.
andsome
foundin thecellsof plants,
fungi,almost
allbacteria,
protists
.
flotfoundin animalcells
.
in different
organisms
madeof ditferent
substances
in plants(formsfibers. . . Thefiberin ourdiet)
Cellulose
Nucleus
. the organelle
in a eukaryotic
cell
thatmanagescellfunctions
. contains
ourDNA
FagureI
Nuclearenvelope
. surrounds
the nucleus
.
is fourlayersthick(2 doublelayers)
.
haslargepores(materials
canpassbetweennucleusandthe restof the cell)
Ghromatin
. Longstrandsof DNA
.
Packsintoidentifiable
chromosomes
when
) ) )
cellsaredividing(reproducing)
Nucleolus
. A regionin the nucleus
. Produces
(calledribosomes)
thatare involvedin protein
tinycellparticles
synthesis
Ribosomes
. Thesitewherethe cellassembles
to the
enzymesandotherproteinsaccording
of the DNA
directions
. Are cellorganelles
. Are NOTboundedby a membrane.
Cytoplasm
. Material
the organelles
thatliesoutsidethe nucleusandsurrounds
. A clearfluid
. Usuallyconstitutes
a littlemorethanhalfthe volumeof an animalcell
. Mostimportant
chemical
reactions
takeplacehere
E.R.
. Endoplasmicreticulum
. A foldedmembrane,
)
surrounded
by cytoplasm
. Hasa largesurfaceareaon whichchemical
reactions
cantakeplace.(A largesurfaceareacan
be packedintoa smallareaby foldingthe surfaces
(thinktissuebox))
. Thesiteof lipidsynthesis
in the cell
. Thereare2 typesof endoplasmic
reticulum
...
RoughE.R.
. Coatedwithribosomes
SmoothE.R.
. Areaof the endoplasmic
reticulum
withoutribosomes
Endopl$rdc
Rltlc$]um
Storagein the cell
Golgiapparatus
Golgiapparatus
New proteins and lipids travel from the E.R to the Gogli body
. seriesof closely-packed,
flattenedmembrane
sacks
(lookslikea stackof pancakes)
. is a sortof sortingcenter
. receivesnewproteinsandlipidsfromthe E,R,
. distributes
proteinsandlipidsto the plasmamembrane
andothercellorganelles
. chemically
modifies
the proteinsit receives
. repackages
proteinsandsendsthemto theirfinal
in the cell
destination
Vacuole
Theytravelin small
membrane-bound
transportpackages(or
vesicles)
Anrtony df tlr€ Pltnt Cill
. spacefor temporary
storageof materials
. sacof fluidsurrounded
by a membrane
. oftenstorefood,enzymes,
andothermaterials
neededby the cell
.Somestorewasteproducts
.A plantcellhasa single
largevacuolethatstores
waterandothersubstances
Lysosomes
. Disassemble
things
. Containdigestive
enzymes
. Digestexcessor worn-outcellparts,food
particles,
virusandbacteria
andinvading
Gytoskeleton
. networkof thin,fibrouselements
. providessupportfor organelles
. dynamicandconstantly
changingstructure
. helpsmaintaincellshape(likepolesin a tent)
. usuallycomposed
of microtubules
andmicrofilaments
Microtubules
. thin,hollowcylinders
madeof protein
. actas trackson whichorganelles
movefromplaceto place
Microfilaments
. thin,solidproteinfibers
- the movement
. important
of wholecellsfromplaceto place
in musclecellcontraction
andin celllocomotion
C ilia
. short,numerous
projections
hair-like
outof the plasmamembrane) t )
. tendto occurin a largenumberon a cell'ssurface
. havea coordinated
beatingactivity
. organisms
thatcontainmanycellshaveciliathatmovefluidsovera cell'ssurface,ratherthanmovingthe cellitself
Theybeatandpropelparticles
of dirtandmucustowards
Ciliacanbe foundin windpipe.
where
theyareexpelled
the mouthandnose,
Flagella
. longerprojections
motion
thatmovewitha whip-like
. cellsthathaveflagellahaveonlyoneor two percell
. in single-celled
ciliaANDflagellaarethe majormeansof locomotion
organisms,
Mitochondria
. organelles
are brokendownto releaseenergy
in whichfoodmolecules
. havean outermembrane
(large
innermembrane
anda highly-folded
surfaceareain a smallspace)
. foundin everycellexceptprokaryotes
Energy-storing
molecules
are produced
on the
cristae)
Ghloroplasts
. foundin plantcells
. the sitewherelightenergyis converted
intouseablechemicalenergy
. storethe chemical
(sugarsandstarches)
energyin foodmolecules
. containthe molecule
(trapsenergyfromsunlightandgivesplantstheirgreencolor)
chlorophyll
. belongto a groupof plantorganelles
calledplastids,
whichare usedfor storage
Chloroplasts
nad Ca[ ClCEtdsi
SflatlF
Thylakoid
membranes- where
lightenergyis
trapped
Stroma:thefluid
the
thatsurrounds
granamembranes