The Cell & Microscrope Flashcards
(28 cards)
What is the classical cell theory?
- All living organisms have one or more cells.
- Cells are the fundamental unit of life.
- All cells come from pre-existing cells.
What is the name given to the hereditary information contained within a cell?
DNA
What are the ocular lenses?
Ocular lenses (or eyepiece) are what you look through to see the image of your specimen.
By how much does the ocular lens increase magnification?
10x
What is the rotating nosepiece?
It is the rotating part of the microscope at the bottom of the body tubes that hold the objective lenses.
What are objective lenses?
The microscope may have 2-3 objective lenses varying in length. Each lenses have a different magnification, the longest one typically having the greatest magnification.
What is the coarse focus knob?
A large round knob on the side of the microscope used to for rough focusing of the specimen; it may move either the stage or the upper part of the microscope.
What is the fine focus knob?
A small round knob on the side of the microscope used to fine tune/sharpen the focus of your specimen.
What is used first; the coarse or fine focus knob?
The coarse focus knob, then the fine focus knob.
What is the “aperture?”
The hole in the stage that allows light through for better viewing of the specimen.
What is the “diaphragm?”
A disc with 5 holes of varying diameter controlling the amount of light that goes through.
Define magnification.
The ratio of enlargement or reduction of an image.
Define resolution.
The ability of a lens system to show fine details of the object being observed.
How do you convert mm into micrometres? Then to nanometers?
Multiply by 1000. Then 1000 again.
Define “Field of View.”
The area visible to you when looking through the eyepiece of the microscope.
Name the technologies to improve microscopy.
Advanced staining techniques, gram staining, lighting techniques, electron microscope.
What does crystal violet (purple) stain?
The cell walls.
What does methylene blue stain?
The nucleus.
What does haematoxylin (blue) stain?
Chromosomes to show mitosis/meiosis.
What is gram staining?
A method of differentiating bacterial species into two large groups based on the physical and chemical properties of their cell walls - gram positive and gram negative.
Bacteria that are stained with crystal violet will either stain purple or pink. What’s the difference between the two?
- Purple bacteria are called “gram positive” and have a thick layer of peptidoglycan in their cell wall.
- Pink bacteria are called “gram negative” and only have a thin layer of peptidoglycan
Pep-tye-doe-glaican.
What is phase contrast microscopy?
It is a contrast-enhancing optical technique used to create high-contrast images of transparent specimens.
What is an advantage of phase contrast microscopy?
It does not kill, fix or stain living cells, therefow allowing the observation of biological processes.
What makes electron microscopes different from light and glass lense microscopes?
They use a high energy beam of electrons rather than light which increases resolution to a limit of 0.2µm.
