Biology Lab: Microscopes

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Questions and Answers

What is the most common type of microscope?

Electron microscope

Phase contrast microscope

Light microscope (correct)

Fluorescence microscope

What is the main advantage of phase contrast microscope?

It allows for viewing of living cells and cell division (correct)

It produces high-quality images

It is extremely simple to use

It is inexpensive to set up

What type of microscope is used to examine blood cells?

Electron microscope

Fluorescence microscope

Stereo microscope

Dark field microscope (correct)

What is the name of the microscope that uses a special condenser and objective with a diaphragm to scatter light?

Dark field microscope Signup and view all the answers

What type of microscope is used to study living cells without killing them by staining?

Phase contrast microscope Signup and view all the answers

What is the main difference between a simple microscope and a compound microscope?

Design and functionality Signup and view all the answers

What type of microscope is used to view the structure of cells clearly?

Dark field microscope Signup and view all the answers

What is the purpose of a microscope in a medical laboratory?

To examine samples Signup and view all the answers

What is the purpose of fixation in sample preparation?

To stabilize the cell and preserve its structure Signup and view all the answers

What is the main difference between TEM and SEM?

The electron beam is scanned across the surface of the sample in SEM Signup and view all the answers

What is the purpose of sputter coating in sample preparation?

To apply a thin layer of conductive material to the sample Signup and view all the answers

What is a disadvantage of using an electron microscope?

It is very expensive to buy and maintain Signup and view all the answers

What is the primary function of a stereo microscope?

To exam insects and help in anatomical dissection Signup and view all the answers

What is the purpose of cryofixation in sample preparation?

To rapidly freeze the sample in liquid nitrogen or liquid helium Signup and view all the answers

What is a digital microscope?

A traditional microscope that uses a digital camera to output an image to a monitor Signup and view all the answers

What is the most frequently used chemical in chemical fixation?

Glutaraldehyde Signup and view all the answers

What is a disadvantage of the microscope type discussed by Hayder Ahmed?

Limited colors (just black and white) Signup and view all the answers

What type of light is used in fluorescence microscopy?

Ultra-violet light Signup and view all the answers

What is the purpose of the special optical filters in fluorescence microscopy?

To absorb colors at all wavelengths, except the wavelength of the dye used Signup and view all the answers

What is the advantage of electron microscopes over light microscopes?

They have a greater resolving power Signup and view all the answers

What lenses are used in electron microscopes?

Electromagnetic and/or electrostatic lenses Signup and view all the answers

Why do electron microscopes have a greater resolving power than light microscopes?

Because they use a shorter wavelength Signup and view all the answers

What is the maximum magnification possible with modern electron microscopes?

About two million times Signup and view all the answers

What is the function of the fluorescent dye in fluorescence microscopy?

To make the sample parts glow Signup and view all the answers

Study Notes

Types of Microscopes

Light microscope: uses light to pass through the sample to produce an image
- Simple microscope: oldest design, magnifies small samples
- Compound microscope: commonly used in medical laboratories

Phase Contrast Microscope

Enhances contrast of transparent and colorless objects by influencing light's optical path
Allows for examination of living cells and cell division without staining

Dark Field Microscope

Uses a special condenser and objective with a diaphragm to scatter light from cells
Cells appear bright on a dark background
Applications: viewing blood cells, bacteria, and cell structure
Advantages: simple to use, inexpensive
Disadvantages: limited to black and white colors

Fluorescence Microscope

Uses fluorescence and phosphorescence to study properties of substances
Uses ultra-violet light to activate specific parts of the sample
Fluorochrome dye is used to make the sample glow
Special optical filters absorb all wavelengths except the dye used

Electron Microscope

Uses a beam of electrons to create an image of the specimen
Capable of higher magnifications and greater resolving power than light microscopes
Types:
- Transmission Electron Microscope (TEM): electron beam passes through the sample
- Scanning Electron Microscope (SEM): electron beam scans the surface of the sample
Disadvantages: expensive, difficult to use

Sample Preparation for Electron Microscope

Fixation: stabilizes the cell using chemical or cryofixation methods
Dehydration
Embedding
Sectioning
Staining
Freezing
Sputter Coating

Stereo Microscope (Dissecting Microscope)

Designed for low magnification to observe the sample using light
Used for examining insects and anatomical dissection

Digital Microscope

Traditional microscope that uses a digital camera to output an image to a monitor

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Description

Identify and describe different types of microscopes used in laboratory settings, including light, phase contrast, dark field, fluorescence, electron, and stereo microscopes.