2.1.1(C) the use of staining in light microscopy

Why is staining used?

Tissues = naturally transparent + when light/electrons go through = you can’t see

So it makes tissue coloured

How does staining work in light microscope?

Dyes absorb some light + reflect others to become visible

Some specimen absorb different dyes depending on chemical nature

How does staining work in electron microscope?

Specimen must be stained to absorb electrons (electrons dont have colour)

Dyes for staining is black or different shades of grey

The dyes are usually heavy metal dyes because they absorb electrons well

What is differential staining?

Specimens stained with multiple dyes to make different tissues show up

Most colours are ———- and are not natural

PHOTOMICROGRAPHS

Meaning its a photograph of what you would see

So there added

WHATT colour of what comes up naturally in a microscope

CHLOROPLASTS (green)

What is a stain that makes subceullar structures blue

TOLUDINE BLUE

Used for DNA or RNA appearing blue in the nucleus

What is phloroglucinol

Used to detect and highlight the presence of lignin in plant cell walls

USUALLY PINK/RED

Are the colours in electron microscope natural?

NO IT IS NOT ITS ADDED