Microscopy

types of microscopes

light microscopes or electron microscopes

how to light microscopes work?

use light and different lenses to magnify objects which allows the image to be seen through an eyepiece

best possible magnification that still has a good resolution for light microscopes

x1000

how does an electron microscope work?

uses electrons to produce detailed images with a high magnification and high resolution

range of magnification of an electron microscope

x200000 to x2000000

types of electron microscopes

transmission electron (TEM) and scanning electron (SEM)

micrograph

photo of specimens taken down the microscop

magnification equation

image size / actual size

process of preparing a slide for a light microscope

if in solution e.g. cheek cells in saliva, add stain

1. take a thin slice of the specimen and place it onto a clean microscope slide

2. add a drop of water or drop of stain onto the specimen

3. take a clean cover slip and lower it slowly onto the specimen, taking care to avoid any air bubbles

magnification

the number of times greater the image is than the specimen

resolution

the ability to distinguish between 2 points on the image

higher resolution = sharper image

types of substances to use for staining

Gram staining, Eosin, Iodine, Methylene blue

staining

used to see cells and cell structures more clearly

different types of stains react with and colour different parts of the cell

function of Gram Staining

stains Gram positive bacteria red and Gram negative bacteria violet

function of Eosin

stains RBC and cell membranes pink or red

function of Iodine in staining

stains starch blue-black

function of Methylene blue in staining

stains nuclei and chromosomes blue

eyepiece lens magnification range on a light microscope

x5 to x15

most commonly used magnifications of objective lenses in light microscopes

x5,x10,x20,x40,x100

what are x100 lenses used with?

immersion oil which connects the bottom of the objective lens to the specimen slide and provides a clearer image

how to calculate total magnification using information from a light microscope

magnifying power of objective lens x magnifying power of eyepiece lens

resolution of the unaided human eye

0.1mm

light microscope diagram with functions

scanning electron microscope diagram

unit conversion