Module 2: Cell Structure Flashcards
What is resolution determined by?
Wavelength of light/beam of electrons.
Define magnification.
How many time larger the image is compared to the object.
Describe a dry mount.
Thin slices or whole specimens on a slide with a cover slip onto.
Give an example of a specimen that a dry mount would be used for.
*plant tissue
*hair
Describe a wet mount.
Specimens added to water/stain before lowering cover-slip on top with a mounted needle.
Why is the cover-slip lowered onto a wet mount with a mounted needle?
To prevent air bubbles forming.
Give an example of a specimen that a wet mount is used for.
Aquatic organisms.
Describe a squash slide.
Wet mounds with a cover-slip pushed on top.
What is the need for a squash slide?
Squash specimen to create thin layer of cells so light can pass through.
Give an example of a specimen that a squash slide is used for.
Root tip.
Describe a smear slide.
The edge of another slide smears the sample across the slide with cover-slip on top.
What is the need for a smear slide?
Creates a smooth, thin, even coating of the specimen.
Give an example of a specimen a smear slide would be used for.
Blood smear.
What is an eyepiece graticule?
A scale in a microscope used to measure specimens.
When do you have to calibrate an eye piece graticule?
Every time the lens is changed.
Explain how to calibrate an eyepiece graticule.
- line up stage micrometer and eyepiece graticule whilst looking through the eyepiece
2, count how many divisions on the eyepiece graticule fit into 1 division on the micrometer scale - each division on micrometer scale is 10 μm, so calculate what 1 division on eyepiece graticule is at that magnification
What is the equation for image size?
Image size = actual size x magnification
What is the purpose of staining samples?
Makes it easier to see, makes parts stand out, make parts contrast.
What is differential staining?
Staining involving many chemicals to stain different parts different colours.
What do crystal violet and methylene blue stain?
Negatively charged parts of the cell.
What do nigrosin and congo red stain?
Background
