Flashcards in Microscope Deck (12):
What are the rules for biological drawing?
Observe the specimen and record what you see clearly and accurately. Labelled drawings and diagrams can be used.
What are some points you need to remember when observing through a microscope?
- Draw what you see, not what you think you should be seeing.
- Always use a sharp pencil
-Make your drawings large
-Make the lines clear and sharp
-Do not shade or colour in any areas
-Make sure the different parts of the drawing are in proportion
-Labels should be spaced neatly around the drawing
What is the difference between electron and light microscopes?
Electron microscopes have a higher resolution and magnification than light microscopes.
What is magnification?
Magnification is how much bigger a sample appears to be under the microscope than it is in real life.
What is resolution?
Resolution is the ability to distinguish between two points on an image i.e. the amount of detail
Pros and cons of electron microscopes
- Expensive to buy
-Expensive to produce electron beam.
-Large and requires special rooms.
-Lengthy and complex sample prep.
-Preparation distorts material.
-Vacuum is required.
-All images in black and white.
-Magnifies over 500 000 times.
-Specimens are dead, as they must be fixed in plastic and viewed in a vacuum
-The electron beam can damage specimens and they must be stained with an electron-dense chemical (usually heavy metals like osmium, lead or gold).
Pros and cons of light microscopes
-Cheap to purchase
-Cheap to operate.
-Small and portable.
-Simple and easy sample preparation.
-Material rarely distorted by preparation.
-Vacuum is not required.
-Natural colour of sample maintained.
-Magnifies objects only up to 2000 times
-Specimens can be living or dead
-Stains are often needed to make the cells visible
What are the main limitations of the electron microscope?
The inability to observe living specimens, difficulty of preparation of samples and expensive equipment are the main limitations.
What are the main limitations of the light microscope?
Low resolution and as a result cannot magnify above x1500 and still give a clear image
What is cell division? (mitosis)
The division of a cell into two daughter cells with the same genetic material.
x 1000 x1000
mm μm nm
Example: 1mm 1000μm 1,000,000nm