Foundations of Biology: Microbiology and Germ Theory

Microbiology

The branch of science that deals with microorganisms/microbes

Microbes

Organisms typically seen with a microscope (with exceptions)

Hippocrates

Greek physician known as father of western medicine; hypothesized that disease had natural causes from within or outside patients

Marco Terenzio Varrone

Roman writer of Rusticae (On Farming) who mentioned minute creatures causing diseases

Aristotle

First to theorize spontaneous generation, believed life could arise from nonliving matter if it contained 'pneuma'

Galileo Galilei

Introduced the scientific method: Observation/Question, Research, Hypothesis, Experiment, Analysis, Conclusion

Robert Hooke

First to describe Microbes and coined the term 'cell'

Antoni Van Leeuwenhoek

Father of microbiology; first to observe protozoa/bacteria

Francesco Redi

Conducted experiments refuting spontaneous generation theory for visible living things

Needham V Spallanzani

Conducted experiments on spontaneous generation in boiled broths

Louis Pasteur

Disproved spontaneous generation, concluded microorganisms came from pre-existing microorganisms

Miasma Theory

Theory that disease comes from unhealthy or polluted air or decomposing material

Ignaz Semmelwas

First to suggest disease transmission via handwashing, reducing mortality rates

John Snow

Linked London cholera outbreaks to water contaminated by sewage

Germ Theory of Disease

Theory stating 'One microbe, one disease'; revolutionized medical practices

Endosymbiotic Theory

Idea that eukaryotic cells originated from one cell engulfing another, forming a beneficial partnership

Mutual Benefits

Engulfed cells living inside larger cells, providing functions like energy production or photosynthesis.

Evolution of New Cells

Swallowed cells evolving into specialized organelles within larger cells over time.

Clinical Microbiology

Microbiology career focusing on diagnosing and treating diseases in clinical settings.

Environmental Biology

Microbiology career studying microbes' roles in natural environments and ecosystems.

Applied Microbiology

Microbiology career applying microbial knowledge to practical fields like biotechnology or agriculture.

Food Microbiology

Microbiology career focusing on studying microbes in food production and safety.

Prokaryotes

Simple, unicellular organisms lacking a nucleus and membrane-bound organelles, replicating via binary fission.

Eukaryotes

Organisms with complex structures, membrane-bound organelles, and nucleus, replicating via mitosis and meiosis.

Viruses

Acellular entities replicating inside host cells, impacting human health and biotechnology.

Light Microscope

Uses light to visualize images, with simple microscopes passing light through one lens and compound microscopes through two lenses.

Magnification

The ability of a lens to enlarge an image compared to the real object, calculated by multiplying objective and ocular lens magnifications.

Resolution

The ability to distinguish two points as separate, influenced by numerical aperture and immersion oil in microscopy.

Bright Field Microscopy

Light focused on specimen, magnified image viewed, limited to observing dead specimens.

Darkfield Microscopy

Viewing unstained, live specimens under a microscope.

Fluorescence Microscopy

Visualizing bright-colored protein structures using fluorophores, suitable for viewing specific molecules in live specimens.

Electron Microscopy (EM)

Uses electrons instead of visible light for high-resolution imaging of small cell structures, with types like TEM and SEM.

Simple Staining

Using basic dyes like Crystal Violet or Methylene Blue to color entire cells for better visibility.

Differential Staining

Technique like Gram staining that highlights specific cell components or characteristics.

Gram Stain

Distinguishes bacteria based on cell wall composition, with Gram-positive bacteria having thick peptidoglycan layers.

Acid-Fast Stain

Differentiates bacteria based on lipid content in the cell wall, with acid-fast bacteria appearing red.

Endospore Stain

Differentiates endospores from vegetative cells, with endospores appearing green.

General Bacteria Characteristics

Unicellular organisms with circular DNA, lacking a nucleus, and having peptidoglycan cell walls.

Cytoplasm

Contains water, essential ions, small organic molecules, and macromolecules in a cell.

Capsule

Protective structure in bacteria that adheres to surfaces and aids in evading immune cells.

Membrane Proteins

Provide structural support, signal detection/release, virulence factor secretion, and ion transport in cells.

Cell Wall

Shapes and protects the cell, with peptidoglycan as a key component for rigidity.

Genus Mycobacterium

Contains mycolic acid in the waxy outer membrane for protection against toxic substances.

Pili vs Fimbriae

Pili are involved in DNA transfer and motility, while fimbriae aid in attachment and motility in bacteria.

Nucleoid

Region in a cell where DNA is organized, serving as the genetic control center.

Ribosomes

Sites for protein synthesis in cells, translating mRNA into proteins, with prokaryotic ribosomes consisting of small and large subunits.

Plasmids

Circular double-stranded DNA replicating independently, carrying genes for antibiotic resistance and toxins.

Inclusions

Store excess nutrients, energy, and waste products, aiding in cell survival under limited conditions.

Endospore

Dormant form of bacteria for survival under harsh conditions, formed from vegetative cells.

Flagellum

External filament propelling cell movement, composed of filament, hook, and basal body.

Flagellar Structure and Function

Flagella are crucial for bacterial motility, with a filament, hook, and basal body driving movement.

Patterns of Flagella Distribution

Polar flagella at cell ends, with variations like monotrichous, amphitrichous, lophotrichous, and peritrichous.

Bacterial Movement - Chemotaxis

Bacteria movement in response to chemical gradients, classified as positive or negative chemotaxis based on chemical stimuli.

Prokaryote

No membrane-bound organelles, primordial nucleus

Eukaryote

Contains a nucleus and membrane-bound organelles

Plasma Membrane

Cholesterol stabilizes animal cell membranes, while hopanoids stabilize bacterial cell membranes

Eukaryotic Flagella and Cilia

Present in eukaryotes, bend back and forth, requiring ATP for movement

Microtubules

Hollow tubes formed from tubulin dimers, involved in cell structure and movement

Intermediate Filament

Strong fiber anchoring nuclear position in cells, composed of intermediate filament protein subunits

Microfilament

Double helix of actin monomers, involved in cell movement and division

Protists

Include water molds, protozoa, and algae, with various structures like cilia, flagella, pseudopodia, and filopodia

Mitochondria

Contains 70s bacterial ribosomes, two lipid membranes, and a mitochondrial matrix

Nucleus

Contains multiple linear DNA chromosomes, a nuclear envelope, pores, lamina, and nucleolus for rRNA synthesis and ribosome assembly

Peroxisome

Organelle involved in hydrogen peroxide metabolism, amino acid and fatty acid breakdown, and lipid synthesis

Endomembrane System

Comprised of membranes like lysosomes, ER, and Golgi apparatus for various cellular functions

ER

Lipid bilayer structure with rough regions for protein synthesis and smooth regions for lipid metabolism and detoxification

Golgi Apparatus

Processes and packages proteins, adding carbohydrates to glycolipids/proteins and proteoglycans

Taxonomy

Science of biological classification, involving distinct classification protocols like phenetic, phylogenetic, and genotypic methods

Binomial Nomenclature

Naming system using genus and species names, following specific rules for formatting and abbreviation

Phenetic Comparison

Comparing organisms based on observable characteristics or phenotype

Phylogenetic Characterization

Organizing organisms based on evolutionary relationships, combining phenotypic and genetic information

Genotypic Characterization

Analyzing genetic sequences to classify organisms, with high similarity indicating relatedness

G+C Content

Measure of guanine and cytosine content in DNA, influencing DNA stability and organism relatedness

Gram Positive Bacteria

Includes Actinomycetes, Streptomycetes, and Micrococcineae, characterized by high G+C content and unique morphology

Firmicutes

Bacteria with low G+C content, diverse shapes, and some important pathogens like Bacillus and Lactobacillus

Mollicutes (mycoplasmas)

Class of bacteria lacking cell walls, with small genomes and unique motility mechanisms

Clostridia

Strict anaerobes forming endospores, known for stickland fermentation and distinct metabolism

Bacilli

Bacteria with diverse shapes, including endospore formers like Bacillus cereus and Bacillus subtilis

Lactobacillales

Order of non-motile, non-spore-forming lactic acid bacteria, used in food fermentation

Proteobacterium Lineages

Includes Alphaproteobacteria and Gammaproteobacteria, with various human pathogens like Escherichia coli

Phylum Thermotogota

Contains thermophiles with high mutation rates and unique growth temperatures

Phylum Cyanobacteria

Oxygenic photosynthetic bacteria producing oxygen, with diverse structures like heterocysts for nitrogen fixation