6457169
Description
Flashcards by Bethany Westwood, updated more than 1 year ago
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Created by Bethany Westwood
over 8 years ago
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| Question | Answer |
| Dry mount | Solid specimen Viewed whole or in thin sections Specimen placed in centre of slide and covered with cover slip |
| Wet mount | Specimen suspended in liquid (water/immersion oil) Cover slip placed on top from angle |
| Squash slides | Wet mount prepared first Lens tissue used to gently press down cover slip Care taken not to break cover slip when squashed |
| Smear slides | Edge of slide smears sample Thin even coating on slide Cover slip placed over slide |
| What things used dry mount? | Hair Pollen Dust Insect parts Muscle tissue Plants |
| What things used wet mount? | Aquatic samples Other living organisms |
| What things use squash slides? | Root tips Soft samples |
| What uses smear slides? | Blood |
| Why is staining done? | Cytosol of cells and cell structures are often transparent Increases the contrast between structures |
| What are the preparation steps of staining? | Sample placed on slide and air dried Heat fixed by passing through a flame Adheres to microscope slide Takes up the stain |
| What does crystal violet/methylene blue stain? | Both positively charged dyes Attracted to negative substances in cytoplasm Stains cell components |
| What does nigrosin/congo red stain? | Negatively charged Stays outside the cell (repelled by negative cytoplasm) Stains the background Cell stands out against the background |
| What technique does nigrosin/congo red stain use? | Negative stain technique |
| What is differential staining? | Distinguishes between 2 types of organisms/organelles that would be hard to identify |
| What is gram stain technique used to do? | Differentiate between gram positive bacteria and gram negative bacteria |
| What are the first 3 steps of gram stain technique? | 1. Crystal violet stain applied 2. Iodine added to fix dye 3. Slide washed with alcohol |
| What is shown after the first 3 steps? | Gram positive - retain stain and appear blue/purple Gram negative - thinner walls, loose stain |
| What are stages 4 and 5 of gram stain technique? | 4. Stained with sofranin dye (counterstain) 5. Bacteria appear red |
| What is shown at the end of gram stain technique? | Gram positive - Susceptible to penicillin which inhibits form of cell walls Gram negative - Thinner walls aren't susceptible to penicillin |
| What is acid fast technique used for? | Differentiate between Mycobacterium and other types of bacteria |
| What are the steps of acid fast technique? | Lipid solvent carries carbolfuchsin die into cells Cells washed with dilute acid-alcohol solution Mycobacterium retain carbofulchsin dye(red) Other bacteria loose stain and exposed to methylene blue |
| General stages of slide preparation | Fixing Sectioning - dehydrated,wax,sliced with microtome Staining Mounting - on slide and cover slip on top |
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