BIO 150 Microbiology: Core Concepts and Learning Objectives

Chapter 1: The Microbial World and You

Introduction

This chapter introduces the foundational concepts of microbiology, focusing on the roles of microorganisms in human life, their classification, and the historical development of the field.

• Microbes in Our Lives: Microorganisms are essential for processes such as decomposition, fermentation, nitrogen fixation, and can also cause diseases.

• Microbiome: The collection of all microorganisms living in association with the human body.

• Normal Microbiota: Microbes that permanently colonize the host without causing disease under normal conditions.

• Transient Microbiota: Microbes present for a short period without causing disease.

• Scientific Nomenclature: Uses a two-part name: Genus and specific epithet (e.g., Escherichia coli).

• Major Groups of Microorganisms: Bacteria, Archaea, Fungi, Protozoa, Algae, Viruses, and Multicellular Animal Parasites.

• Three Domains: Bacteria, Archaea, Eukarya.

• Historical Observations: Hooke observed cells; van Leeuwenhoek observed live microorganisms.

• Spontaneous Generation vs. Biogenesis: Spontaneous generation posited life arises from nonliving matter; biogenesis states life arises from preexisting life.

• Key Contributors:

  • Needham: Supported spontaneous generation.

  • Spallanzani: Disproved spontaneous generation with sealed flasks.

  • Virchow: Proposed biogenesis.

  • Pasteur: Disproved spontaneous generation with swan-neck flask experiment.

• Paster's Influence: Led to Lister's antiseptic techniques and Koch's postulates for disease causation.

• Koch's Postulates: Criteria to establish a causative relationship between a microbe and a disease.

• Jenner: Developed the first vaccine (smallpox).

• Ehrlich and Fleming: Ehrlich developed chemotherapy; Fleming discovered penicillin.

• Subfields: Bacteriology (bacteria), Mycology (fungi), Parasitology (parasites), Immunology (immune system), Virology (viruses).

• Modern Microbiology: Microbial genetics, molecular biology, and genomics are crucial for understanding and manipulating microbes.

• Beneficial Activities: Decomposition, fermentation, bioremediation, production of antibiotics and vitamins.

• Biotechnology: Use of microbes in industrial processes; recombinant DNA technology allows genetic modification.

• Resistance: The ability of organisms to withstand antimicrobial agents.

• Biofilm: A complex aggregation of microbes attached to a surface.

• Emerging Infectious Disease: New or changing diseases increasing in incidence.

Chapter 4: Functional Anatomy of Prokaryotic and Eukaryotic Cells

Introduction

This chapter explores the structural and functional differences between prokaryotic and eukaryotic cells, focusing on bacterial anatomy and physiology.

• Prokaryotic vs. Eukaryotic Cells:

  • Prokaryotes: No nucleus, no membrane-bound organelles, usually smaller.

  • Eukaryotes: True nucleus, membrane-bound organelles, larger size.

• Bacterial Shapes and Arrangements: Cocci (spherical), Bacilli (rod-shaped), Spirilla (spiral); arrangements include chains, clusters, pairs. Pleomorphism is variability in shape.

• Chromosomes: Prokaryotes have a single, circular chromosome; eukaryotes have multiple, linear chromosomes.

• Plasmids: Small, circular DNA molecules in prokaryotes; often carry antibiotic resistance genes.

• Capsule and Glycocalyx: Protective outer layers; capsules are organized, glycocalyx is unorganized.

• Surface Structures:

  • Flagella: Motility structures.

  • Axial filaments: Found in spirochetes, enable corkscrew movement.

  • Fimbriae: Attachment structures.

  • Pili: Involved in DNA transfer (conjugation).

• Cell Walls:

  • Gram-positive: Thick peptidoglycan, teichoic acids.

  • Gram-negative: Thin peptidoglycan, outer membrane with lipopolysaccharide.

  • Acid-fast: Mycolic acid layer (e.g., Mycobacterium).

  • Archaea: Pseudomurein or protein walls.

  • Mycoplasmas: Lack cell walls.

• Staining: Gram stain differentiates based on cell wall structure.

• Protoplast, Spheroplast, L form: Variants of bacteria with altered or absent cell walls.

• Plasma Membrane: Phospholipid bilayer; functions in transport, energy generation.

• Transport Mechanisms:

  • Simple diffusion: Movement down concentration gradient.

  • Facilitated diffusion: Uses transport proteins.

  • Osmosis: Water movement across membrane.

  • Active transport: Requires energy.

  • Group translocation: Substance chemically modified during transport.

• Nucleoid and Ribosomes: Nucleoid contains DNA; ribosomes synthesize proteins.

• Inclusions: Storage granules (e.g., polysaccharide granules, lipid inclusions, sulfur granules, gas vacuoles).

• Endospores: Resistant, dormant structures formed by some bacteria (e.g., Bacillus, Clostridium).

• Flagellar Arrangements: Monotrichous (single), Lophotrichous (tuft), Amphitrichous (both ends), Peritrichous (all over).

• Prokaryotic vs. Eukaryotic Flagella: Structure and movement differ; eukaryotic flagella have a 9+2 microtubule arrangement.

• Organelles (Eukaryotes):

  • Nucleus: Contains DNA.

  • Endoplasmic Reticulum: Protein and lipid synthesis.

  • Golgi Complex: Protein modification and sorting.

  • Lysosomes: Digestive enzymes.

  • Vacuoles: Storage.

  • Mitochondria: ATP production.

  • Chloroplasts: Photosynthesis.

  • Peroxisomes: Oxidative reactions.

  • Centrosomes: Cell division.

Chapter 10: Classification of Microorganisms

Introduction

This chapter covers the principles and methods used to classify and identify microorganisms, including taxonomy, phylogeny, and molecular techniques.

• Taxonomy: Science of classification; taxon is a group of organisms; phylogeny is evolutionary history.

• Two-Kingdom System: Limited; does not account for prokaryotes or molecular differences.

• Key Contributors:

  • Linnaeus: Binomial nomenclature.

  • Whittaker: Five-kingdom system.

  • Woese: Three-domain system based on rRNA.

• Three-Domain System: Bacteria, Archaea, Eukarya; reflects genetic relationships.

• Major Taxa: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

• Culture, Clone, Strain: Culture is a population of microbes; clone is a population from a single cell; strain is a genetic variant.

• Multicellular Eukarya: Differentiated by cell structure, nutrition, and reproduction.

• Protist: Unicellular eukaryote not classified as plant, animal, or fungus.

• Species Definitions: Eukaryotic species can reproduce; prokaryotic species are defined by genetic similarity; viral species by host range and genetics.

• Classification vs. Identification: Classification groups organisms; identification determines identity of an unknown.

• Bergey's Manual: Reference for bacterial classification and identification.

• Identification Methods:

  • Staining and biochemical tests.

  • Serological tests (antibody-based).

  • Phage typing (bacteriophage susceptibility).

  • DNA-based methods: Sequencing, fingerprinting, PCR, nucleic acid hybridization, DNA chips, ribotyping, FISH.

• Western vs. Southern Blotting: Western detects proteins; Southern detects DNA.

• Dichotomous Key vs. Cladogram: Dichotomous key is a stepwise identification tool; cladogram shows evolutionary relationships.

Chapter 12: The Eukaryotes: Fungi, Algae, Protozoa, and Helminths

Introduction

This chapter examines the diversity, structure, and significance of eukaryotic microorganisms, including fungi, algae, protozoa, and helminths.

• Fungi: Eukaryotic, chitin cell walls, absorb nutrients.

• Mold vs. Yeast: Molds are multicellular, filamentous; yeasts are unicellular, non-filamentous.

• Mold Structure: Thallus (body), hyphae (filaments), mycelium (mass of hyphae).

• Dimorphic Fungi: Can exist as mold or yeast forms.

• Fungal Reproduction: Asexual (spores by mitosis), sexual (spores by meiosis and fusion).

• Adaptations: Tolerate low pH, high osmotic pressure, low moisture.

• Types of Fungal Infections: Superficial, cutaneous, subcutaneous, systemic, opportunistic.

• Pathogenic Fungi:

  • Rhizopus: Systemic infection.

  • Aspergillus: Systemic infection.

  • Trichophyton: Cutaneous infection.

  • Cryptococcus: Systemic infection.

  • Pneumocystis: Opportunistic infection.

  • Candida: Opportunistic infection.

• Beneficial Fungi: Saccharomyces cerevisiae (baking, brewing), Aspergillus niger (citric acid), Penicillium (antibiotics).

• Algae: Domain Eukarya, Kingdom Protista; photosynthetic, aquatic, cellulose cell walls.

• Beneficial Algae: Brown algae (algin), red algae (agar, carrageenan).

• Harmful Algae: Diatoms (domoic acid), dinoflagellates (red tides, toxins).

• Protozoa: Unicellular, eukaryotic, lack cell walls, motile.

• Trophozoite: Active, feeding stage; Cyst: Dormant, resistant stage.

• Amoeba vs. Apicomplexa: Amoebas move by pseudopods; apicomplexa are non-motile, obligate intracellular parasites.

• Protozoan Diseases:

  • Entamoeba: Amoebic dysentery.

  • Toxoplasma: Toxoplasmosis.

  • Plasmodium: Malaria.

• Hosts: Intermediate host harbors larval stage; definitive host harbors adult stage.

• Slime Molds: Cellular (individual cells), plasmodial (multinucleate mass).

• Parasitic Helminths: Multicellular, reduced digestive and nervous systems, complex life cycles.

• Platyhelminthes vs. Nematodes: Flatworms vs. roundworms.

• Trematodes (Flukes): Leaf-shaped, suckers; Cestodes (Tapeworms): Segmented, absorb nutrients.

• Nematode Eggs Infective to Humans: Ascaris lumbricoides, Enterobius vermicularis.

• Arthropod Vector: Animal that transmits pathogens (e.g., insects, ticks).

• Common Arthropod Vectors:

  • Lyme disease: Tick

  • Malaria: Mosquito

  • African Trypanosomiasis: Tsetse fly

  • Chaga’s Disease: Kissing bug