Course Overview

This study guide summarizes the key topics, laboratory skills, and academic expectations for Microbiology (Biology 251) at Great Basin College. The course covers the taxonomy, morphology, physiology, infectious diseases, and ecology of microorganisms, with a strong emphasis on laboratory techniques and scientific reasoning.

Core Microbiology Topics

Fundamentals of Microbiology

Microbiology is the study of microscopic organisms, including bacteria, viruses, fungi, protozoa, and algae. Understanding their structure, function, and role in the environment and disease is essential for life science and health majors.

• Taxonomy: The classification and naming of microorganisms based on shared characteristics.

• Morphology: Study of the shape, size, and structure of microorganisms.

• Physiology: Examination of microbial metabolism and growth.

• Ecology: Interactions of microbes with each other and their environments.

• Infectious Diseases: How microbes cause disease in humans and other organisms.

Microscopy

Microscopy is fundamental for observing microorganisms, which are too small to be seen with the naked eye.

• Types of Microscopes: Light microscopes, electron microscopes, and specialized staining techniques.

• Staining: Methods such as Gram stain, acid-fast stain, and endospore stain help differentiate microbial types.

• Application: Used to identify cell structures, observe motility, and distinguish between prokaryotic and eukaryotic cells.

Functional Anatomy of Cells

Understanding the structure of prokaryotic and eukaryotic cells is crucial for identifying microbes and understanding their functions.

• Prokaryotic Cells: Lack a nucleus; include bacteria and archaea. Key features: cell wall, plasma membrane, ribosomes, and sometimes flagella or pili.

• Eukaryotic Cells: Have a nucleus and membrane-bound organelles; include fungi, protozoa, algae, and helminths.

• Cell Walls: Composition varies (e.g., peptidoglycan in bacteria, chitin in fungi).

• Relevance to Disease: Cell wall structure affects susceptibility to antibiotics and immune responses.

Microbial Metabolism

Microbial metabolism encompasses the chemical reactions that allow microbes to grow, reproduce, and interact with their environment.

• Catabolism: Breakdown of molecules to release energy.

• Anabolism: Synthesis of complex molecules from simpler ones.

• Fermentation: Anaerobic process producing acids, gases, or alcohols.

• Enzyme Activity: Enzymes catalyze metabolic reactions; affected by temperature, pH, and inhibitors.

• Example Equation: Glycolysis:

Microbial Growth and Control

Microbial growth refers to the increase in number of cells, not cell size. Controlling microbial growth is essential in medical and laboratory settings.

• Growth Requirements: Nutrients, temperature, pH, oxygen, and water.

• Control Methods: Sterilization, disinfection, antiseptics, and use of antibiotics.

• Laboratory Techniques: Aseptic technique, streak plates, and use of selective/differential media.

• Example: Handwashing experiment to assess effectiveness of different control methods.

Microbial Genetics

Microbial genetics explores how genetic information is stored, expressed, and transferred in microorganisms.

• DNA Replication: Process by which bacteria duplicate their genetic material.

• Gene Expression: Transcription and translation of genes into proteins.

• Genetic Variation: Mutation, transformation, conjugation, and transduction.

• Antibiotic Resistance: Evolution of resistance through genetic changes.

• Example: pGLO bacterial transformation experiment.

Classification and Diversity of Microorganisms

Microorganisms are classified based on genetic, structural, and metabolic characteristics.

• Domains: Bacteria, Archaea, Eukarya.

• Medically Relevant Microbes: Bacteria (e.g., Escherichia coli), viruses (e.g., influenza), fungi (e.g., Candida), protozoa (e.g., Plasmodium), and helminths.

• Identification Techniques: Biochemical tests (IMViC series), staining, and molecular methods.

Viruses and Prions

Viruses are acellular infectious agents; prions are infectious proteins.

• Structure: Nucleic acid core (DNA or RNA) surrounded by a protein coat.

• Replication: Require host cells for reproduction.

• Diseases: Influenza, HIV/AIDS, Ebola, rabies, and prion diseases like BSE.

Principles of Disease and Epidemiology

Understanding how diseases spread and are controlled is a key aspect of microbiology.

• Pathogenicity: Ability of a microbe to cause disease.

• Epidemiology: Study of disease distribution and determinants in populations.

• Control Strategies: Vaccination, sanitation, and antimicrobial drugs.

Laboratory Skills and Techniques

Aseptic Technique

Aseptic technique prevents contamination of cultures and the environment.

• Key Steps: Sterilizing equipment, minimizing exposure, and proper transfer of cultures.

• Applications: Essential for isolation and identification of microbes.

Staining and Microscopy

• Simple Stain: Uses a single dye to highlight cells.

• Gram Stain: Differentiates bacteria into Gram-positive and Gram-negative based on cell wall structure.

• Special Stains: Acid-fast, endospore, capsule, and flagella stains.

Culturing and Identification

• Media Preparation: Use of agar plates, slants, and broths for growing microbes.

• Isolation Techniques: Streak plate method for obtaining pure cultures.

• Biochemical Tests: IMViC series (Indole, Methyl Red, Voges-Proskauer, Citrate), oxidase, catalase, and coagulase tests.

• Unknown Identification: Integrating staining, culturing, and biochemical results to identify an unknown microbe.

Antimicrobial Evaluation

• Antiseptics and Disinfectants: Testing effectiveness against microbes.

• Antibiotic Sensitivity: Evaluating bacterial resistance using disk diffusion methods.

Genetic Transformation

• pGLO Experiment: Introduction of foreign DNA into bacteria to observe gene expression (e.g., fluorescence).

Lab Report Structure

• Introduction: Background and objective of the experiment.

• Procedures: Detailed methods and materials used.

• Results: Presentation of data, including tables and figures.

• Conclusion: Interpretation and significance of findings.

Note: Use computer-generated tables and graphs, label all figures, and write in past tense.

Assessment and Grading

Grading Scale:

Major Laboratory Exercises

PowerPoint Presentation Topics

Students will research and present on a disease or a notable figure in microbiology. Example topics include:

• Diseases: Hepatitis B/C, Lyme Disease, Covid-19, Malaria, Cholera, Tetanus, AIDS/HIV, Tuberculosis, MRSA, Ebola, Influenza, etc.

• Scientists: Louis Pasteur, Robert Koch, Alexander Fleming, Carl Woese, Alice Evans, Esther Lederberg, John Snow, etc.

Learning Outcomes

• Describe the structure and function of prokaryotic and eukaryotic cells.

• Apply aseptic techniques and culture methods in the laboratory.

• Explain microbial growth requirements and control strategies.

• Compare genetic mechanisms in microbes and their role in antibiotic resistance.

• Demonstrate understanding of microbial diversity and medically relevant examples.

Scientific Reasoning and Academic Integrity

• Apply scientific methodologies and reasoning to laboratory and theoretical problems.

• Maintain academic honesty in all coursework and laboratory activities.

Additional info:

• This guide is based on the course syllabus and schedule, which align with standard college-level microbiology curricula.

• For detailed protocols and background, refer to the course textbook: Microbiology, an Introduction (Tortora, Funke, & Case, 14th ed.).