Chapter 2.1 - Microscopy and calibration Flashcards
What is resolution?
The ability to distinguish between two separate points that are very close together
What is magnification?
The number of times greater an image is than the object
How do you calculate magnification?
Image size/Real size
How do you convert from cm - mm - μm - nm?
cm - mm = x 10
mm - μm = x 1000
μm - nm = x 1000
What is a photomicrograph?
A photograph taken through a microscope
What are the four types of sample preparation?
- Dry mount
- Wet mount
- Squash slides
- Smear slides
How can samples be prepared on a dry mount?
- Solid specimens are sectioned(cut into very thin slices with a sharp blade) or viewed whole
- It is placed on the centre of a slide and a coverslip is placed over the sample
How can samples be prepared on a wet mount?
- Specimens are suspended in a liquids such as water or an immersion oil
- A coverslip is placed on from an angle
How can samples be prepared on squash slides?
- A wet mount is prepared first, then a lens tissue is used to gently press down on the coverslip
- Depending on the material, potential damage to a coverslip can be avoided by squashing the sample between two microscope slides
How can samples be prepared on smear slides?
- The edge of a slide is used to smear the sample, creating a thin, even coating on another slide
- A coverslip is placed over the sample
How do you calibrate a microscope?
- Fix the stage micrometer(on the stage) into place on the stage
- Look through the eyepiece lens to line up the micrometer and eyepiece graticule(inside eyepiece)
- Count the number of graticule divisions that fit into one micrometer division
- Use the formula, graticule division = size of one micrometer division / number of graticule divisions, to calculate the size of each graticule division at that magnification
What are stains?
Coloured chemicals that bind to molecules in or on the specimen, increasing contrast
Why are stains used?
Most of a cell is transparent and so stains bind to certain structures to increase contrast, this allows components to become more visible
What is differential staining?
Stains that bind to specific chemicals
What is the gram stain technique?
It is a technique used to separate bacteria into two groups, gram-positive and gram-negative bacteria
