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what is magnification?
how many times larger an object appears
What is resolution?
the minimum distance between two distinct points where they can still be seen as separate objects
on the stage micrometer 1 division
0.01 mm
2 main microscopes
optical microscope and electron microscope
electron microscopes types
transmission electron microscope (2d)
scanning electron (3d)
in light microscopes, why can’t we see the organelles?
max resolution and mag
200nm and mag is 1500x
how electron microscope works - TEM
coats spectrum in resin to form solid block
thin slices are made, and stained with heavy metals
electrons pass thru the thin slice of material and are absorbed by the heavier stained metals. As they pass, they are photographed by electromagnets on the film.
TEM captures . SEM captures _.
tem organelles. sem is whole cells, tissues, organisms
scanning is about
how it’s reflected
steps of how scanning electron microscope works
specium coated w/ thin layer of metal (like gold, tungsten, silver) to improve conductivity
electrons are reflected from the surface of specium, producing a 3D shape
limits of electron microscope
complex, expensive, can’t look at living cells, ARTEFACTS can be made from preperation, black and white
how to observe the cells in a prepared slide using light microscope
clip slide onto stage
select lowest powered objective lens
use course knob to bring stage just below objective lens
look down the eyepiece and use coarse knob to move stage down till image is roughly focused
adjust focus with fine knob till image is clear
if greater magnification is required refocus using a higher powered objective lens
artefact
things that shouldn’t be there bc of staining in electron microscope
Temporary mount
where the specimen is suspended in a drop liquid on the slide. the microscopy which Enchances colour of the spec
Why is the resolution of Electron microscope higher than the resolution of a image using optical
electrons have much shorter wavelengths than photons (light particles), allowing them to resolve smaller details
how to measure for size of a structure (real)
measure image in mm and divide by mag
convert image to micrometres
divide image size by length of scale
multiply real length of scale bar
Why is it important for a leaf tissue to be very thin when observed
Thiness allows for light to pass thru specimun
What are the measurement conversions needed for magnification?
describe the steps to preparing a microscope slide using a temporary mount?
- begin by pipetting a small drop of water onto the centre of the slide.
2
- you will then need to place a thin section of your specimen on top of the water drop through using tweezers.
3
- add a drop of stain. stains are used to highlight objects in a cell.
4
-add a cover slip.
-do this by standing the slide upright on the slide, next to the water droplet.
-carefully tilt and lower so specimen is covered.
-ensure no air bubbles are seen. they'll obstruct view of specimen.
describe how you could make a temporary mount of a piece of plant tissue to observe the position of starch grains in the cells when using an optical light
add a drop of water to glass slide
obtain thin slice of plant tissue and place slice on drop pf water
stain with iodine in potassium odiine
lower cover slip using mounted needle