methods of studying cells Flashcards
what is the first step before studying individual organelles
tissue is cut up
what is tissue kept in after being cut up + why
cold, buffered, isotonic solution
cold - so any digestive enzymes don’t break up cells
buffered - so ph wont change
isotonic - WP same in + out of cells - otherwise cells would burst from osmotic shock
how is tissue then further broken down
in a homogeniser
what is the name of teh machine the prepared, blended tissue is spun in
ultracentrifuge
what is the first spin in the centrifuge
low speed for 10 minutes
what is the role of the homogeniser
to blend everything evenly
what is the spun tissue called
supernatant 1,2,3
what is the result of the first, low speed spin
nucleus is heaviest
will sink to bottom
removed from supernatant 1
what is the part that sinks in after being spun called
sediment
what is the second spin
medium speed
what is the sediment in supernatant 2
chloroplasts + mitochondria
why is the third and final spin
high speed
what is found in supernatant 3
ribosomes
what is separating organelles by spinning them called
cell fractionation
what are the advantages of a compound light microscope
cheap
light and mobile
able to view living organisms
sows colour
what makes compound light microscopes identifiable
2 lenses
disadvantages to a compound light microscope
low magnification (x2000 max)
what is identifiable about transmission electron microscopes
electron gun
4 lenses each with a different purpose
fluorescent screen
advantages of transmission electron microscopes
much higher magnification
higher resolution
disadvantages of a transmission electron microscope
expensive
large
non-living specimens only
no colour
2D images only
difficult to create slides
may produce artefacts
what is the magnification of transmission electron microscopes
20,000-30,000 magnification
what do scanning electron microscope
images do
takes images from different angles
electrons reflect off
3D image is created off of these images
what is the magnification of optical light microscopes
1500-2000
what is the magnification of transmission electron microscopes
up to 50,000,000
what is the magnification of scanning electron microscope
up to 1,000,000
what is the limitations of scanning electron microscopes
requires a vacuum
only dead specimens
may produce artifacts
what are artefacts
features that appear in the image that aren’t part of the specimen
often come in the preparation process
there was a time where scientists could differentiae between atrifacts and organelles
formula for magnification
IAM magnification =size of image/actual size of specimen
