Data table 1 microscope components

Microscopy for Microbiology – Use and Function Hands-On Labs, Inc. Version 42-0249-00-02

Review the safety materials and wear goggles when working with chemicals. Read the entire exercise before you begin. Take time to organize the materials you will need and set aside a safe work space in which to complete the exercise.

Experiment Summary:

You will identify the components of an optical microscope. You will describe field of view and depth of field. You will view a series of preserved specimens including protozoans, fungi, and bacteria. You will prepare wet mounts of cheek cells and dental tartar.

EXPERIMENT

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Learning Objectives Upon completion of this laboratory, you will be able to:

● Outline the components of an optical microscope.

● Describe field of view and depth of field.

● Calculate the total magnification and field of view for the lenses of an optical microscope.

● Examine prepared slides under scanning, low, high, and oil immersion lenses.

● Prepare wet mounts of cheek cells and dental plaque and examine them under different lenses.

Time Allocation: 3.5 hours

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Experiment Microscopy for Microbiology - Use and Function

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Experiment Microscopy for Microbiology - Use and Function

Materials Student Supplied Materials

Quantity Item Description 1 Camera, digital or smartphone 1 Distilled water 1 Roll of paper towels

HOL Supplied Materials

Quantity Item Description 2 Blank slides 1 Pair of gloves 1 Lens paper (50 sheets) 1 Long thin stem pipet 1 Metric ruler 1 Safety goggles 1 Slide Box:

1 – Slide – Amoeba, whole mount 1 – Slide – Bacteria bacillus form 1 – Slide – Bacteria coccus form 1 – Slide – Bacteria spirillum 1 – Slide – Letter e focusing slide 1 – Slide – Penicillium with Conidia 1 – Slide – Yeast, whole mount

1 Slide cover glass cube 1 Sterile swabs, 2 per pack 1 Student microscope with 100x oil immersion lens*

1 - Immersion Oil

*Microscopes and oil immersion lens are purchased separately from the LabPaq kit.

Note: To fully and accurately complete all lab exercises, you will need access to:

1. A computer to upload digital camera images.

2. Basic photo editing software, such as Microsoft Word® or PowerPoint®, to add labels, leader lines, or text to digital photos.

3. Subject-specific textbook or appropriate reference resources from lecture content or other suggested resources.

Note: The packaging and/or materials in this LabPaq kit may differ slightly from that which is listed above. For an exact listing of materials, refer to the Contents List included in your LabPaq kit.

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Experiment Microscopy for Microbiology - Use and Function

Background Optical Microscopes

A microscope is an optical instrument that uses a lens or a series of lenses to magnify objects that are either too small to be seen by the naked eye, or to view distinct details of an object that are not visible to the naked eye. There are three main categories of microscopes: optical, electron, and scanning probe.

Optical microscopes, also referred to as light microscopes, use reflected visible light and a series of two or more convex lenses to magnify and focus an object. The most common type of light microscope is the compound microscope, which utilizes a lens of short focal length and a second lens of a longer focal length. The short lens forms and focuses the image, and the longer lens magnifies and further focuses the image. Compound microscopes are able to resolve objects to a resolution of approximately 200 nm (0.2 µm). Resolving power is the ability to discern two objects as separate, and is limited by the wavelength of light. As compound microscopes utilize reflected visible light, the resolution of the microscope is limited by the wavelength of the visible light.

The components of a compound microscope work together to create a magnified image. See Figure 1. The description of each of the parts is discussed on the following page.

Figure 1. Main components of a compound microscope. © Picsfive

The ocular lens is located at the top of the microscope. This short lens is termed “ocular” as it the lens that one looks through in order to view the image. An ocular lens is typically 10x or 15x power and is often referred to as the eye piece. A microscope with one ocular lens is called a monocular microscope, a microscope with two ocular lenses is called a binocular microscope (as shown in Figure 1), and a microscope with two ocular lenses and a location for a camera is called a trinocular microscope.

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Experiment Microscopy for Microbiology - Use and Function

The objective lenses of a microscope are found closest to the stage and are held by the turret, or revolving nose piece. The turret allows the lenses to be easily rotated to select the lens that offers the necessary power of magnification. There are typically three to four objective lenses on a microscope, ranging in power from 4x to 100x. The lowest p