Ch. 3 - Observing Microorganisms Through a Microscope

Tortora - Microbiology: An Introduction 14th Edition

Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook

Tortora 14th Edition

Ch. 3 - Observing Microorganisms Through a Microscope

Problem 2

Chapter 3, Problem 2

Three-dimensional images of live cells can be produced with:
a. Darkfield microscopy
b. Fluorescence microscopy
c. Transmission electron microscopy
d. Confocal microscopy
e. Phase-contrast microscopy

Verified step by step guidance

Step 1: Understand the goal of the question, which is to identify the microscopy technique capable of producing three-dimensional images of live cells.

Step 2: Review each microscopy option and its capabilities: a) Darkfield microscopy enhances contrast but does not produce 3D images; b) Fluorescence microscopy highlights specific structures but typically produces 2D images; c) Transmission electron microscopy provides high-resolution images but requires fixed, dead samples and is 2D; d) Confocal microscopy uses laser scanning and optical sectioning to create detailed 3D images of live cells; e) Phase-contrast microscopy enhances contrast in transparent specimens but does not create 3D images.

Step 3: Focus on the principle of confocal microscopy, which involves scanning a specimen with a focused laser beam and collecting light from a single focal plane, allowing the construction of 3D images by stacking multiple optical sections.

Step 4: Recognize that confocal microscopy is uniquely suited for live cell imaging in three dimensions due to its ability to optically section specimens without physical slicing.

Step 5: Conclude that the correct answer is confocal microscopy, as it is the only technique listed that can produce three-dimensional images of live cells.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Confocal Microscopy

Confocal microscopy uses laser light and spatial pinholes to eliminate out-of-focus light, producing sharp, high-resolution images. It allows for optical sectioning of thick specimens, enabling the reconstruction of three-dimensional images of live cells.

Fluorescence Microscopy

Fluorescence microscopy uses fluorescent dyes or proteins to label specific cell components, which emit light when excited by specific wavelengths. While it provides high contrast images, it typically produces two-dimensional images unless combined with techniques like confocal microscopy.

Transmission Electron Microscopy (TEM)

TEM uses electron beams transmitted through ultra-thin specimens to produce highly detailed images at the molecular level. However, it requires fixed, dead samples and cannot produce three-dimensional images of live cells.

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Transmission Electron Microscope (TEM)

Related Practice

Textbook Question

Fill in the following blanks.

a. 1 μm = ______ m

b. 1= _______ 10⁻⁹ m

c. 1 μm = ______ nm

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Textbook Question

Assume you stain Bacillus by applying malachite green with heat and then counterstain with safranin. Through the microscope, the green structures are

a. Cell walls

b. Capsules

c. Endospores

d. Flagella

e. Impossible to identify

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Textbook Question

Looking at the cell of a photosynthetic microorganism, you observe the chloroplasts are green in brightfield microscopy and red in fluorescence microscopy. You conclude:

a. Chlorophyll is fluorescent

b. The magnification has distorted the image

c. You’re not looking at the same structure in both microscopes

d. The stain masked the green color

e. None of the above

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Textbook Question

Which type of microscope would be best to use to observe each of the following?

a. A stained bacterial smear

b. Unstained bacterial cells: the cells are small, and no detail is needed

c. Unstained live tissue when it is desirable to see some intracellular detail