Module 2 - Cell Structure Flashcards
What are stains?
Coloured chemicals that bind to molecules in or on the specimen, making it easier to see
Name an all purpose stain
Methylene blue
What is differential staining?
A stain that binds to specific structures, staining each structure differently so they can be easily identified with a single stain
Give examples of some differential stains
- Acetic orcein binds to DNA and stains chromosomes dark red
- Eosin stains cytoplasm; Sudan red stains lipids
- Iodine (in potassium iodide solution stains cellulose in plant cell walls yellow or starch granules blue/black
What is the formula for magnification
M = I/A
How do you prepare a specimen
1) Dehydrate it
2) embed it in wax to prevent distortion during slicing
3) using a special instrument make small slices called sections
What is the Resolution of Light Microscope?
0.2 um
What is the magnification of the SEM?
200,000 X
What is the Magnification, Resolution and how is the image shown for a TEM?
resolution : 0.0002 um
Magnification: 1 mil
The electrons are absorbed and reflected and the image is 2D
How is the image shown using SEM?
The image is 3D and the electrons bounce off the surface of the specimen
Which two microscopes use dead specimens?
TEM and SEM
What is the magnification for Light Microscope?
1500 X
MAKING SLIDES
- Thin slice of specimen
- place specimen onto slide using tweezers
- Using a mounted needle, put cover slip onto slide over specimen (this prevents air bubbles)
- Close Microscope with clips
What are the similarities of Prokaryotes and Eukaryotes
- Both have plasma membrane
- Both have a cytoplasm
- Both have ribosomes for protein synthesis
- Both have DNA and RNA
What are differences of Prokaryotes to Eukaryotes?
- smaller
- no nucleus
- free floating DNA
- No membrane bound organelles
- Flagella
- Pili (adhere host)
- Waxy capsule surrounding cell wall
- Cell wall
