MMG2010 2025 Microbiology Notes

Course Overview

• Microbial World topics covered in this course (MMG2010 2025):

  • Course overview

  • What is microbiology?

  • Naming and Classifying Microorganisms

  • Microbes and Human Welfare

  • Microbes and Human Disease

• Course code and year reference: MMG2010 2025

What You Will Need

• Required materials:

  • Brightspace (online learning platform)

  • Lecture sessions

  • Laboratory sessions

  • Respondus Lockdown Browser (for secured assessments)

• Recommended materials for those interested in the source material:

  • Practice Test

  • Friday in-class activities

  • Textbook: Microbiology, openstax.org (free; open access)

Questions About the Course and Contact Information

• When emailing, include the course number and use your UVM email account

• Lecture contact: Rebecca Guy, 114A Stafford Hall

• Laboratory contact: Karin Hodge, 116 Stafford Hall

Grading and Assessments

• Overall grade composition (as per syllabus):

  • Lecture: 60 ext{%}

  • Laboratory: 40 ext{%}

• Breakdown of assessments (as listed):

  • Exams (4): 60 ext{%}

  • Pre-lab Homework: 5 ext{%}

  • Study Questions: 15 ext{%}

  • Lab Report: 10 ext{%}

  • Major Unknown Report: 10 ext{%}

• Important policy: Students must pass both lecture and lab to pass the course. Assessments are not accepted past the due date; late assessments receive a grade of zero.

Taxonomy Recap (Recall)

• Taxonomy history and system:

  • Carl Linnaeus, 1735 developed the Binomial nomenclature system

  • Italicize family, genus, species, and variety or subspecies

  • Traditional taxonomic ranks: Kingdom, Phylum, Class, Order, Suborder

  • Italics usage: Genus species (e.g., Genus species)

• Modern Taxonomy:

  • 3 Domain system (Carl Woese, 1977)

  • Based on rRNA sequences

  • LUCA: Last Universal Common Ancestor

• Taxonomic levels to remember (from broad to specific):

  • Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

  • For a visual cue, see the standard hierarchy figure references (e.g., Figure 10.1, Microbiology: An Introduction, 14th ed.).

• Key takeaway: Taxonomy provides a structured way to name and classify organisms, reflecting evolutionary relationships.

3-Domain System (Taxa and Hierarchy)

• Taxa levels (from broad to specific):

  • Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

• This hierarchical scheme helps place organisms based on genetic relationships (rRNA-based) rather than solely on visible traits.

• Visual cue: The standard taxonomy diagram associates these ranks with organisms at different levels of relatedness.

What is Microbiology?

• Etymology:

  • "Micro" + "Biology" → literally the study of small living things

  • Scientifically: study of microbes (microorganisms and viruses)

• Major groups studied in microbiology:

  • Bacteria

  • Yeast and Mold (Fungi, yeast/mold variants)

  • Protists

  • Helminths (parasitic worms)

  • Viruses

• Practical implication: Microbiology encompasses a wide range of life forms, from single-celled bacteria to multicellular parasites and acellular viruses, all of which have broad impacts on health, environment, and industry.

How Small is Small?

• Size scale reference (Foundations in Microbiology, Talaro & Talaro, 2001):

  • $1 ext{ mm} = 1000 ext{ } ext{μm}$

  • $1 ext{ μm} = 1 ext{ micrometer} = 1 ext{ micron}$

  • Red blood cell width ≈ $6-8 ext{ μm}$

• Significance: Microbes occupy scales from single micrometers (bacteria, many protists) down to viruses that are ~20–300 nm in size; these scales influence imaging, culturing, and measurement in microbiology.

Scope of Microbiology

• Subdisciplines include:

  • Bacteriology: study of bacteria

  • Mycology: study of fungi

  • Protozoology: study of protozoa

  • Phycology: study of algae

  • Parasitology: study of disease-causing parasites (protozoa and helminths)

  • Virology: study of viruses

• Interdisciplinary relevance: overlaps with genetics, biochemistry, ecology, medicine, and environmental science.

Types of Microorganisms (Overview)

• Major groups:

  • Bacteria

  • Archaea

  • Fungi

  • Protozoa

  • Algae

  • Multicellular animals (some microorganisms)

  • Viruses

• Context: These categories form the basis for understanding microbial diversity and the roles each group plays in ecosystems and human affairs.

Bacteria

• Characteristics:

  • Prokaryotes (no nucleus)

  • Unicellular

  • Cell wall containing peptidoglycan (PG)

  • Reproduction primarily asexual

  • Metabolism includes chemotrophs and phototrophs

  • Motility: variable (sometimes)

• Pathogenicity:

  • Pathogenic to humans/animals/plants: Yes

Archaea

• Characteristics:

  • Prokaryotes

  • Cell wall structure different from bacteria; No peptidoglycan (PG)

  • Reproduction: asexual

  • Metabolism: chemotrophs

  • Often extremophiles (thriving in extreme conditions)

  • Motility: Sometimes

• Pathogenicity:

  • Pathogenic to humans/animals/plants: No

• Note: Archaea share the same cellular organization as bacteria but differ in biochemistry and genetics; they are frequently found in extreme environments and in many natural habitats.

Fungi

• Characteristics:

  • Eukaryotes

  • Can be unicellular (yeasts) or multicellular (molds, mushrooms)

  • Cell walls contain chitin

  • Reproduction: both asexual and sexual

  • Metabolism: chemotrophs

  • Motility: generally none

• Pathogenicity:

  • Pathogenic to humans/animals/plants: Yes

Algae

• Characteristics:

  • Eukaryotes

  • Can be unicellular or multicellular

  • Cell walls contain cellulose

  • Reproduction: asexual and sexual

  • Metabolism: phototrophs (produce their own food via photosynthesis)

  • Motility: variable

• Pathogenicity:

  • Pathogenic to humans/animals/plants: No

Protozoa

• Characteristics:

  • Eukaryotes

  • Typically unicellular

  • Cell walls: None

  • Reproduction: both asexual and sexual

  • Metabolism: chemotrophs and phototrophs

  • Motility: variable

• Pathogenicity:

  • Pathogenic to humans/animals/plants: Yes

Parasitic Worms (Helminths)

• Characteristics:

  • Eukaryotes

  • Multicellular animals

  • Cell walls: None

  • Reproduction: both asexual and sexual

  • Metabolism: chemotrophs

  • Motility: yes (in life stages)

• Pathogenicity:

  • Pathogenic to humans/animals/plants: Yes (termed helminths)

Parasitology

• Definition: The study of protozoa and parasitic worms

• Emphasis on organisms that cause disease and on life cycles, hosts, and transmission dynamics

• Context: A foundational subfield that links microbiology with medicine and public health

Viruses

• Characteristics:

  • Not assigned to a cellular domain

  • Acellular particles

  • No cell wall

  • Reproduction: cannot replicate independently; require a host cell (obligate intracellular parasites)

  • Metabolism: none independently

  • Motility: none

• Pathogenicity:

  • Pathogenic to every organism type: Yes (viruses infect bacteria, plants, animals, humans, etc.)

Microbes and You: Roles of Microbes

• The Good (benefits and services):

  • Food chain support and nutrient cycling

  • Decomposition of organic waste

  • Nitrogen fixation: incorporation of N₂ into organic compounds

  • Oxygen production via photosynthesis

  • Fermented foods (e.g., dairy, vegetables, beverages)

  • Biotechnology applications

  • Medicine (diagnostics, therapeutics, vaccines, antimicrobials)

  • Human microbiome and its influence on health and disease

• The Bad (detriments):

  • Pathogenesis (disease-causing potential)

  • Food spoilage and contamination

• Takeaway: Microbes play essential roles in ecosystems, industry, and health, with both beneficial and harmful impacts depending on context

There Would Be No Life on Earth Without Microbes

• Foundational concept highlighted in Brock’s Biology of Microorganisms (16th edition) and other microbiology texts

• Emphasizes the central role of microbes in Earth's biosphere and biogeochemical cycles

Learning Objectives (What You Should Be Able to Do)

• After this lecture and readings, you should be able to:

  • List several ways microbes affect our lives

  • List at least four beneficial activities of microorganisms

  • Define the following terms: bacteriology, mycology, parasitology, immunology, and virology

  • Differentiate the major characteristics of each group of microorganisms (including viruses)

  • Convert between metric units in the following scales: centi-, milli-, micro-, nano-, and pico- (practice with examples)

  • List the taxonomic hierarchy from domain to species

  • Demonstrate proper usage of the binomial nomenclature system (italicization and formatting conventions)

• Reference: MMG2010 2025 learning objectives

Quick Reference: Binomial Nomenclature and Italics

• Binomial nomenclature convention:

  • Each species name consists of two parts: the genus name and the specific epithet (species descriptor)

  • Example: Genus species (both in italics)

• Formatting reminder: Genus is capitalized; species is not; both are italicized in scientific writing

• Taxonomic emphasis: Distinguishes organisms with shared ancestry and helps standardize communication across languages and regions

Quick Reference: Common Units and Comparisons

• Length scales (examples):

  • $1 ext{ mm} = 1000 ext{ μm}$

  • $1 ext{ μm} = 1 ext{ micrometer} = 1 ext{ micron}$

  • Red blood cell width: $6-8 ext{ μm}$

• These conversions underpin microscopy, measurement, and microbial sizing in coursework and lab work

Quick Reference: Taxonomic Hierarchy (Mnemonic)

• Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

• Visual cue: Use a standard phylogenetic tree to remember relationships and naming conventions

• Modern taxonomy emphasizes genetic relationships (e.g., rRNA-based distinctions in the 3-domain system)

Key Reminders for Exams and Practical Work

• Be able to recognize and explain the differences among the major microbial groups (Bacteria, Archaea, Fungi, Protozoa, Algae, Viruses, Helminths)

• Understand the significance of the LUCA concept and how it informs the 3-domain system

• Practice converting between metric prefixes and units, including meter-based scales from nano- to pico- (and centi-, milli-, micro- as applicable)

• Be comfortable with binomial nomenclature formatting and italicization conventions in written work

• Recall the scope and roles of microbes in health, industry, and the environment, along with ethical and biosafety considerations when handling microorganisms