Week 3 Microscopy Techniques and Applications

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Questions and Answers

What is the primary technique used in phase contrast microscopy?

Enhancing color in images

Transmitting light through thick samples

Observing specimens in their natural state (correct)

Highlighting three-dimensional structures

Which of the following microscopy techniques is most suitable for viewing live, unaltered samples?

Phase contrast microscopy (correct)

Fluorescent microscopy

Brightfield microscopy

Scanning electron microscopy

What effect does brightfield microscopy rely on to visualize samples?

Light illumination (correct)

Fluorescent markers

Light absorption

Reflected light

In darkfield microscopy, what is the purpose of the opaque disc under the condenser lens?

To block direct light from entering the objective Signup and view all the answers

What is the total magnification if the objective lens is 40× and the eyepiece magnification is 10×?

400× Signup and view all the answers

Which type of microscope would likely provide the highest resolution for cellular structures?

Electron microscope Signup and view all the answers

Which characteristic of cells makes them difficult to see using brightfield microscopy?

Cells are usually thin and transparent Signup and view all the answers

What distinguishes fluorescence microscopy from other forms of microscopy?

It uses fluorescent markers to illuminate samples Signup and view all the answers

Which statement about magnification in microscopy is true?

Total magnification is the product of eyepiece and objective magnifications Signup and view all the answers

What does darkfield microscopy primarily accomplish by using oblique light?

Illuminates the specimen on a dark background Signup and view all the answers

Who first described fluorescence and in what year?

Stokes, 1852 Signup and view all the answers

What color do DAPI and Hoechst emit when excited by UV light?

Blue Signup and view all the answers

What is the primary function of immunofluorescence?

To label specific proteins within a cell Signup and view all the answers

Which microscopy technique is known for producing 3-D images?

Confocal microscopy Signup and view all the answers

Which statement accurately describes two-photon microscopy?

It allows for deeper tissue penetration. Signup and view all the answers

What is a significant advantage of electron microscopy over optical microscopy?

It provides higher magnification and resolution. Signup and view all the answers

What type of light is generally used in fluorescence microscopy?

Laser light or visible light Signup and view all the answers

What does the presence of a green fluorophore in immunofluorescence indicate?

The presence of insulin in the cell. Signup and view all the answers

Which component primarily binds to DNA in DAPI and Hoechst stains?

The minor groove of DNA Signup and view all the answers

Which microscopy technique primarily relies on electrons instead of light to create images?

Electron microscopy Signup and view all the answers

Study Notes

Microscopy

Cells are the fundamental building blocks of all living organisms.
Microscopes are crucial tools for studying the structure and function of cells.
Optical microscopes use visible light to illuminate and magnify specimens:
- Brightfield microscopy illuminates the sample from below, making it appear dark against a bright background.
- Darkfield microscopy uses a special condenser to illuminate the sample from the sides, creating a bright specimen against a dark background.
- Phase contrast microscopy enhances the contrast of transparent specimens by manipulating the phase of light passing through them.
- Fluorescence microscopy uses fluorescent dyes to label specific structures or molecules within the cell.
  - DAPI and Hoechst are commonly used to highlight the nuclei of cells.
- Confocal microscopy uses lasers to scan the sample, creating a three-dimensional image by eliminating out-of-focus light.
  - Confocal microscopy is a powerful technique for studying the structure of cells and tissues.
Electron microscopes use a beam of electrons to illuminate and magnify specimens:
- Transmission electron microscopy (TEM) uses electrons that pass through the specimen to create an image.
- Scanning electron microscopy (SEM) uses electrons that are scattered from the surface of the specimen to create an image.
- Electron microscopes have much higher magnification and resolution than optical microscopes, allowing the visualization of individual molecules and organelles.

Magnification

The total magnification of a compound microscope is determined by multiplying the magnification of the objective lens by the magnification of the eyepiece.
For example, a 10x objective lens and a 10x eyepiece would produce a total magnification of 100x.

Summary

Optical microscopes use light to illuminate and magnify.
Electron microscopes use electrons to illuminate and magnify.
Electron microscopes have a higher magnification and resolution than optical microscopes.

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Description

Explore the various microscopy techniques used to study cells, including brightfield, darkfield, phase contrast, fluorescence, and confocal microscopy. This quiz will test your knowledge on the principles and applications of these fundamental tools in biology. Learn how each method enhances our understanding of cellular structures and functions.