T1 Cell structure Flashcards
(117 cards)
chromatic aberration
production of images with light split into different colours, prevented since 1800s via combination of 2 images.
optical microscopes
where light focussed through a series of lenses magnifies objects up to 100 times.
magnification
number of times larger an object appears compared to actual size.
magnification lens equation
objective lens power * eyepiece lens power
resolution
ability to distinguish between close together but separate objects
dissecting microscope function
used for observation at low magnification
wet mount
temporary preparation in which specimen and a drop of fluid are trapped under a coverslip so thin tissue sections can be seen.
non-viable stains
for use on dead specimens
viable specimens
for use on alive specimens
iodine stain
tests for starch, turning blue-black
crystal violet stain
tests for gram/nucleus, turning purple
aniline sulfate stain
tests for lignin, turning yellow
methylene blue stain
nuclei turns blue
hematoxylin and eosin
H turns nucleus blue/violet
E turns proteins red/pink
difference between a compound microscope and dissecting microscope
compound produces a 2d image through a thin, transparent sample// dissecting produces a 3d image, looking at surface details.
compound has smaller distance between the lens and the specimen
example of mounting liquid
water, glycerol, stain
why must specimens be so thin?
so that light can pass through so that features can more easily be seen.
Also to reduce the number of layers of cells.
function of coverslip
to exclude air bubbles that obscure the view of the specimen/ to smooth out the specimen.
why is the lowest magnification always used first?
allows a larger area to be viewed so that specific areas can be more easily located. Also, makes focussing easier, protects slide from large movements.
stain function
enhancement of specific features of a sample
electron microscopes
use short wavelengths of electrons to produce high resolution images of small specimens
SEM
scanning electron microscope
electrons bounce off surface of object to produce detailed images of external appearance.
TEM
transmission electron microscope
TEM process
electrons pass through specimen and are scattered.
magnetic lenses focus the image onto a fluorescent screen/photographic plate.