B1 - microscopy

Created by

mariam

Cards (11)

Microsopes let us see things we can't see with the naked eye
Resolution is the ability to distinguish between two points
High resolutions gives a sharper image
Light microscopes use light and lenses to form image of specimen and magnify it
Can see individual cells and large subcellular structures e.g nucleus
An electron microsope has a higher magnification and resolution than light microscope
Cells can be studied in finer detail
Allowed biologists to see and understand subcellular structures
magnification = image size/real size
x 1000 - mm to micrometres
x 1000 - micrometres to nanometres
to prepare animal cells for examination
put small drop of water on slide
swap inside of mouth with clean cotton bud
rub cotton bud on drop of water
to prepare plant cells for examination
put small drop of water on slide
peel onion skin from inside of leaves in onion bulb
use forceps to place onion skin flat without air bubbles on drop of water
stain cells with iodine
to prepare hair or fur for examination
put small drop of glycerol on slide
cut small piece of hair or fur
use forceps to transfer to drop of glycerol
place coverslip over specimen
put drop of stain next to coverslip
draw stain under coverslip by placing filter paper next to it
light microscope practical
rotate objective lense so low power is in line with stage
turn coarse focus so stage is close to objective lens
place slide on stage
focus slide by adjusting coarse focus
draw low power image
rotate objective so high power objective is in line with stage
bring slide back into focus using fine focus adjustment
in the light microscope practical, a low power diagram is used
it is used to show outline of individual cells that make up tissue
it is used as a plan to show arrangement of regions of tissue
a high power diagram produced to make detailed image
disadvantages of light microscope
image willbecome blurry
resolution is 200nm
cannot distinguish two points closer than 200nm