Microscopes

Question 1

What are some features of a light microscope?

Answer 1

• light reflected/scatter to the objective is then imaged back at the eyes
• specimen is living or dead
• x2000 magnification
• 200nm Resolution
• stains are used

Question 2

What is a light microscope?

Answer 2

• when light shines down through the objective onto the specimen

Question 3

What are the features of a laser scanning confocal microscope?

Answer 3

• only light radiated from very close to the local plane is detected
• living and non-living specimen
• x400 magnification
• 120nm resolution
• 2D and 3D images produced at different focal points

Question 4

what is a laser scanning confocal microscope?

Answer 4

• it is when emitted light from the specimen is fitted through a pinhole

Question 5

what are some features of a Transmission electron microscope

Answer 5

• non-living specimen
• x500 000 magnification
• 0.5nm resolution
• 2D images
• black and white images

Question 6

what is a Transmission electron microscope?

Answer 6

• it is a beam of electrons is transmitted through a specimen and focused to produce an image

Question 7

what are the features of a Scannning Electron Microscope?

Answer 7

• specimen is non-living
• x500 000 magnification
• 3-10nm Resolution
• 3D images
• Black and white images

Question 8

what is a Scannning Electron Microscope?

Answer 8

• It is a beam of electrons is sent across the surface of a specimen and the reflected electrons are collected

Question 9

Stains are used for specific biochemicals, what are they used for?

Answer 9

• iodine solution stains starch granules blue and black; methylene blue stains genetic material in animal cells blue
• In confocal microscopy, fluorescent dyes can be used to tag specific molecules

Question 10

Why is staining used for microscopes?

Answer 10

• To make cells more visible
• To increase contrast
• Identify different cell components

Question 11

What is the resolution of a microscope?

Answer 11

• The ability to distinguish between objects that are very close together - higher resolution means more detail
• They cannot be seen using optical microscopes because its resolution is too low

Question 12

what is magnification of a microscope?

Answer 12

• The number of times greater the size of the image is that the size of the real object.
• Magnification = Image size/size of object

Question 13

what is meant by calibrating a microscope?

Answer 13

• It means to work out each division on the gracticule measures (on the stage micrometer) at a particular magnification

Question 14

How is the calculation done for a stage micrometer and gracticule?

Answer 14

1 gracticule division = a number of micrometers/ number of gracticle divisions.

graticle divisions x magnification factor = measurement (um)