cells
Lightmicroscope
use a pair of convex glass lenses
wavelength of light restricts its resolution
Magnification
calculation magnification size of image
size of real object
Resolution
minimumdistanceapart that two objects can bedistinguished as two
separate objects
cell fractionation
placetissue in a cold buffered solution of the same water potential as
the tissue cold to reduceenzymeactivity that mightbreak downorganelles
same water potential to prevent cells shrinking or bursting
bufferedso pHdoes not fluctuate
2stages homogenation cells brokendown by a homogeniser to release
organellesfromcells homogenate filtered to
remove complete cells large pieces of debris
ultra centrifugation spinfilteredhomogenate in a centrifuge at
a highspeed
heaviest organelles are sedimented at the
bottom fluid on top is called supernatant
supernatanttransferredto another tubeand
spun at a fasterspeed sediments nextheavies
Electron microscope
TEM a beam of elecfrons focused onto specimen by condenserelectromagnet
denser areas absorb more electrons so appear darker
electrons have short wavelength sohigher resolution
electrons passthrough thin specimen
limitations cannotlook at living material
specimen must be very thin
artefact present
complexstainingprocess
only 2D imagesproduced
SEM directs beam of electrons on surfaceof specimen from above rather
than penetrating from below
beam passed back and forth across a portionof specimen in a patter
electrons scattered by specimen depends on contoursofspecimen surfac
3Dimage
Limitations for TEMapplybut specimendoesnotneed tobe extremely thin
Eukaryotic cell structure
IEEE'arenteiophetitibietrmentarianneeineatismittingsmiteitsatisreourierosomes
membrane is continuous with endoplasmic reticulum of the cell andoften has
ribosomes on its surface controls entry and exit of material
nuclear pores allow passage of large molecules e.g RNA out of nucleus
nucleoplasm granular jelly like material makes up the bulk of themateria
chromosomes contain protein bound linear DNA
nucleolus small spericalregionwithin the nucleoplasm which manufacture
ribosomalRNA and assembles the ribosomes
, mitochondrion site of aerobicrespiration responsible for productionof ATP
double membrane controls entry and exit of material
cristae inner 2 membranes to formextensions large s A
foldingof remainder
matrix makes up of mitochondrion containsproteins lipids
ribosomesandDNA that allow the mitochondriatocontrolproductionof ownproteins
chloroplasts out photosynthesis
carry
chloroplast envelope double plasma membrane that surrounds organelle
and is highly selective in what it allows to enter and leave the cell
grana stacks of up to 100 disc like structures called thylakoids
chlorophyll is within the thylakoids light absorption
some thylakoids have tubular extensions that join up withthylakoid
stroma a fluid filled matrix where secondstage of photosynthesis
endoplasmic reticulum is continuous with the outer nuclear membrane
theyenclose a network of tubules and flattened sacs called cisternae
roughendoplasmic reticulum RtR ribosomespresent on outersurfaces
of membrane Functions larges A forsynthesisofproteinsandglycoproteins
path fortransport of materials throughthecell
smooth endoplasmic reticulum lacks ribosomes on its surface
Functions synthesise store and transport lipids
synthesise store and transportcarbohydrates
golgi apparatus consist of a stack ofmembranes that make up fluid filled
flattened and curved sacs or cisternae with small rounded hollow structures
called vesicles Functions add carbohydrate to proteins to formglycoprotei
producesecretory enzymes such as those secreted
the
by walls pancreas secretecarbohydratessuch as thoseused in makin
cell in plants form lysosomes
modifies triglyceridescombinestriglycerides with
Bigtseisnomesdpointedeswintetiergiciesseprodieditysiine
Golgiapparatus contain
enzymes such as proteases and lipasesThey are digestiveenzymes bound by a
single membrane containlysozyme s enzymes that hydrolyse cell walls ofbacteri
lysosomes isolate these enzymes from the rest of the cell before releasing
them either to the outside or into a phagocyticvesicle within the cell
Functions hydrolyse material ingestedby phagocytic cells e gwiseandbacteria
release enzymes to outside of cell to destroy material exocytosis
digest worn out organelles so useful chemicals can be re used
completely break down cells after they have died autolysis
ribosomes cytoplasmicgranules occur in cytoplasm or may be associated
EightE s 588ftreticiarryotiitcheii's around as nm in diameter
770s prokaryotic cells mitochondria and chloroplastsslightlysmalle
cell wall consists of microfibrils ofcelluloseembedded in a matrix
Functions provide mechanical strength in order to prevent cell bursting
give mechanical strength to the plant as a whole
allow water to pass along it and so contribute to movement of
water through the plant
cell walls of algae are made up of eithercellulose or glycoprotein or both
cell walls of fungido not contain cellulose but consists of chitin
vacuoles a fluid filled sac bounded by a single membrane tonoplast
Plant vacuole contains solution ofmineral salts sugars aminoacids wastes pigmen
Functions supportherbaceousplantspartsofwoodyplantsbymakingcells turgid
Sugars and aminoacidsmay act as temporaryfoodstore
pigmentsmaycolourpetals to attract pollinatinginsects
Lightmicroscope
use a pair of convex glass lenses
wavelength of light restricts its resolution
Magnification
calculation magnification size of image
size of real object
Resolution
minimumdistanceapart that two objects can bedistinguished as two
separate objects
cell fractionation
placetissue in a cold buffered solution of the same water potential as
the tissue cold to reduceenzymeactivity that mightbreak downorganelles
same water potential to prevent cells shrinking or bursting
bufferedso pHdoes not fluctuate
2stages homogenation cells brokendown by a homogeniser to release
organellesfromcells homogenate filtered to
remove complete cells large pieces of debris
ultra centrifugation spinfilteredhomogenate in a centrifuge at
a highspeed
heaviest organelles are sedimented at the
bottom fluid on top is called supernatant
supernatanttransferredto another tubeand
spun at a fasterspeed sediments nextheavies
Electron microscope
TEM a beam of elecfrons focused onto specimen by condenserelectromagnet
denser areas absorb more electrons so appear darker
electrons have short wavelength sohigher resolution
electrons passthrough thin specimen
limitations cannotlook at living material
specimen must be very thin
artefact present
complexstainingprocess
only 2D imagesproduced
SEM directs beam of electrons on surfaceof specimen from above rather
than penetrating from below
beam passed back and forth across a portionof specimen in a patter
electrons scattered by specimen depends on contoursofspecimen surfac
3Dimage
Limitations for TEMapplybut specimendoesnotneed tobe extremely thin
Eukaryotic cell structure
IEEE'arenteiophetitibietrmentarianneeineatismittingsmiteitsatisreourierosomes
membrane is continuous with endoplasmic reticulum of the cell andoften has
ribosomes on its surface controls entry and exit of material
nuclear pores allow passage of large molecules e.g RNA out of nucleus
nucleoplasm granular jelly like material makes up the bulk of themateria
chromosomes contain protein bound linear DNA
nucleolus small spericalregionwithin the nucleoplasm which manufacture
ribosomalRNA and assembles the ribosomes
, mitochondrion site of aerobicrespiration responsible for productionof ATP
double membrane controls entry and exit of material
cristae inner 2 membranes to formextensions large s A
foldingof remainder
matrix makes up of mitochondrion containsproteins lipids
ribosomesandDNA that allow the mitochondriatocontrolproductionof ownproteins
chloroplasts out photosynthesis
carry
chloroplast envelope double plasma membrane that surrounds organelle
and is highly selective in what it allows to enter and leave the cell
grana stacks of up to 100 disc like structures called thylakoids
chlorophyll is within the thylakoids light absorption
some thylakoids have tubular extensions that join up withthylakoid
stroma a fluid filled matrix where secondstage of photosynthesis
endoplasmic reticulum is continuous with the outer nuclear membrane
theyenclose a network of tubules and flattened sacs called cisternae
roughendoplasmic reticulum RtR ribosomespresent on outersurfaces
of membrane Functions larges A forsynthesisofproteinsandglycoproteins
path fortransport of materials throughthecell
smooth endoplasmic reticulum lacks ribosomes on its surface
Functions synthesise store and transport lipids
synthesise store and transportcarbohydrates
golgi apparatus consist of a stack ofmembranes that make up fluid filled
flattened and curved sacs or cisternae with small rounded hollow structures
called vesicles Functions add carbohydrate to proteins to formglycoprotei
producesecretory enzymes such as those secreted
the
by walls pancreas secretecarbohydratessuch as thoseused in makin
cell in plants form lysosomes
modifies triglyceridescombinestriglycerides with
Bigtseisnomesdpointedeswintetiergiciesseprodieditysiine
Golgiapparatus contain
enzymes such as proteases and lipasesThey are digestiveenzymes bound by a
single membrane containlysozyme s enzymes that hydrolyse cell walls ofbacteri
lysosomes isolate these enzymes from the rest of the cell before releasing
them either to the outside or into a phagocyticvesicle within the cell
Functions hydrolyse material ingestedby phagocytic cells e gwiseandbacteria
release enzymes to outside of cell to destroy material exocytosis
digest worn out organelles so useful chemicals can be re used
completely break down cells after they have died autolysis
ribosomes cytoplasmicgranules occur in cytoplasm or may be associated
EightE s 588ftreticiarryotiitcheii's around as nm in diameter
770s prokaryotic cells mitochondria and chloroplastsslightlysmalle
cell wall consists of microfibrils ofcelluloseembedded in a matrix
Functions provide mechanical strength in order to prevent cell bursting
give mechanical strength to the plant as a whole
allow water to pass along it and so contribute to movement of
water through the plant
cell walls of algae are made up of eithercellulose or glycoprotein or both
cell walls of fungido not contain cellulose but consists of chitin
vacuoles a fluid filled sac bounded by a single membrane tonoplast
Plant vacuole contains solution ofmineral salts sugars aminoacids wastes pigmen
Functions supportherbaceousplantspartsofwoodyplantsbymakingcells turgid
Sugars and aminoacidsmay act as temporaryfoodstore
pigmentsmaycolourpetals to attract pollinatinginsects
