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Questions and Answers
Cytology is the study of microorganisms.
Cytology is the study of microorganisms.
False
Simple staining involves the application of multiple reagents.
Simple staining involves the application of multiple reagents.
False
A microscope should be handled with fingers touching the lenses.
A microscope should be handled with fingers touching the lenses.
False
Fixation is necessary to stop enzymatic activity in cells.
Fixation is necessary to stop enzymatic activity in cells.
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Bacterial smears from solid media should be diluted before applying to the slide.
Bacterial smears from solid media should be diluted before applying to the slide.
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The microscope should be positioned at least 15 cm away from the edge of a table.
The microscope should be positioned at least 15 cm away from the edge of a table.
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It is important to ensure that the low-power objective is in position before storing the microscope.
It is important to ensure that the low-power objective is in position before storing the microscope.
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Cellular proteins can ionize as either an acid or a base, making them amphoteric substances.
Cellular proteins can ionize as either an acid or a base, making them amphoteric substances.
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Study Notes
FDE305 - Food Microbiology Laboratory: Microscopic Examination of Microorganisms, Microscope Care, and Simple Staining
- Course Focus: Examine microorganisms, use microscopes, and perform simple staining techniques relevant to food microbiology.
Objectives
- Understand the parts and functions of a microscope
- Know how to use a microscope effectively
- Master the preparation and staining of bacterial smears
- Identify basic bacterial shapes following staining
- Properly locate and examine stained bacterial smears
Introduction
- Cytology Defined: The study of cells and their components
- Microscopic Structures: Cellular structures not easily visible without magnification
- Differential Staining: A cytological technique using multiple reagents to highlight specific cellular features
- Simple Staining: Applying a single stain or reagent to highlight specimen features
Introduction: Staining Principles
- Chemical Reactions: Chemicals react with substances, producing color changes, specific to cell type or structure
- Amphoteric Molecules: Cellular proteins and amino acids, can be acid or base depending on environments
- Stain Functionality: To be effective, a stain needs to display color and be able to act as an acid or base
Introduction: Preparing Specimens
- Cell Preparation: To allow observation of microscopic structures, cells need preparation: sufficiently thin layers on slide, enough light passing through sample.
- Smear Preparation (Broth & Solid Media): For broth cultures, the suspension is directly placed on a slide. For solid media, a portion of the growth is emulsified with a liquid on a slide.
- Fixation: Crucial for preventing cell distortion, stopping enzymatic activity that can damage cells if they were to die. This also helps the cells adhere to the slide.
Microscopic Examination of Microorganisms
- Microscope Care: Upright position, keep it 15cm+ away from the table edge. Do not handle lenses directly, ensure that the low-power objective lines up in the working position.
- Avoid Contamination: Inspect tools for contaminants, do not touch lenses with bare fingers, protect microscope from chemicals.
- Oil Immersion: Use oil for enhanced light transmission during high-power viewing. Properly remove any remaining oil using lens paper
- Simple Staining Procedure: Preparation of smear, heat fixation, applying the stain, rinsing, and observation under the microscope.
Simple Staining Procedure Steps
- Smear Preparation: Prepare a smear from a bacterial culture.
- Heat Fixing: Heat-fix the smear.
- Staining: Apply a staining agent to the smear.
- Rinsing: Rinse the excess stain.
- Observing: Observe the stained sample under a microscope with the appropriate objective lens. Note any color (type of stain) or shape distinctions between microorganisms.
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Description
Test your knowledge on food microbiology through this quiz focusing on microscope use, staining techniques, and identification of microorganisms. Explore the principles of cytology and the various methods for preparing and examining bacterial smears.
