Question Answer
Micro biology Scientific study of (mostly) living things that can’t be seen directly, must be analyzed through indirect methods in addition to using microscopes
Pro-kary: pre nucleus Bacteria and archaea do not have a nucleus and have been traditionally classified as prokaryotes
About 10x smaller than eukaryotic cells
Single celled
Lack organelles: small, double-membrane-bound structures that perform specific functions
Eu-kary: true nucleus Cells with a nucleus are classified as eukaryotes
Bacteria and Archaea Prokaryotes
Unicellular, lack nuclei
Smaller than eukaryotes
Some extreme envs
Reproduce asexually
Bacterial cell walls vs Archaeal cell walls
Protozoa Single-celled eukaryotes
Similar to animals in nutrient needs and cellular structure
Live in water or animal hosts
Asexual (most) and sexual reproduction
Most are capable of locomotion
Pseudopods, Cilia, Flagella
How Are Microbes Classified? Protozoa, Bacteria and Archaea, algae, fungi
algae Unicellular or multicellular eukaryotes
Simple reproductive structures
composition of cell wall
fungi Eukaryotic
Obtain food from other organisms
cell walls
Molds – multicellular; grow as long filaments; reproduce by sexual and asexual spores
Yeasts – unicellular; reproduce asexually by budding
Parasitic worms (helminths) Eukaryotic, multicellular
Complex life cycles, intermediate hosts
Many macroscopic (except for eggs)
Many ways of entry, disrupt variety of tissues
viruses Not living
Acellular (proteins and nucleic acids)
Must have living cell to reproduce
No metabolism
Bacteria are ubiquitous!
bacteria Global estimate of:
5 1030 cells
They are found:
Deep in the earth’s crust
Polar ice caps
Hot springs & geysers
Inside & outside the bodies of plants and animals
You have more bacterial than human cells!
The Impact of Microorganisms
on Humans 1
Microorganisms inhabiting humans outnumber human cells 10 to 1
Does not include red blood cells
Make up 1-3% of body mass (2-6 lbs)

The Impact of Microorganisms
on Humans 2
More than 10,000 species identified
360x more bacterial genes (8 million unique protein-coding genes) than human genes (30,000)
And we have 37% genetic similarity to bacteria!
Microorganisms can be both beneficial and harmful to humans
Viruses in Nature Total prokaryotic cells on Earth = 1030
Total viruses on Earth = 1031
Most of the genetic diversity on Earth is thought to reside in viruses
Evolution and the Extent of Microbial Life 1 Life on Earth through the Ages
Earth is 4.6 billion years old
First cells: 3.8 billion years ago

Evolution and the Extent of Microbial Life 2 Life was exclusively microbial until ~1 billion years ago
Microbial biomass is significant and cells are key reservoirs of essential nutrients (e.g., C, P, N)
Photosynthetic microorganisms (bacteria and algae) account for more than 70% of the earth’s photosynthesis, contributing the majority of the oxygen to the atmosphere
Pathogen: any agent such as a virus, bacterium, fungus, protozoan, or helminth that causes disease.
Nearly ______ different microbes can cause disease 2,000
Disease: collection of signs and symptoms that alters homeostasis in a host in a negative way
The Impact of Microorganisms on Humans Emphasis typically on harmful microorganisms (infectious disease agents, or pathogens)
Control of infectious disease during last century
Characteristics of Effective Scientists Curiosity
Readiness to revise their views of natural processes as new discoveries are made
1500s Fracastoro “germs of contagion” in epidemic diseases, can be transferred by direct/indirect contact
Robert Hooke: First observations of microbes in the 1600’s
Antone van Leeuwenhoek 1700s: Made a crude microscope to examine threads in fabrics
Made drawings of what he called “animalcules” in rainwater and scraped from his teeth
Louis Pasteur (1822–1895) and the Defeat of Spontaneous Generation
Louis Pasteur (1822–1895) Disproved theory of spontaneous generation
Living things can originate from anything non-living
Sterile: completely free of all life forms including endospores and virus particles.
Louis Pasteur Discovered that living organisms discriminate between optical isomers
Discovered that alcoholic fermentation was a biologically mediated process (originally thought to be purely chemical)
Developed vaccines for anthrax, fowl cholera, and rabies
Scientific method: Scientific method: General approach taken by scientists to explain a natural phenomenon
If experimentation supports the hypothesis, it is not immediately accepted as fact
The hypothesis must be tested and retested
Leads to a THEORY if continually validated
Robert Koch (1843–1910) Infectious Disease, and the Rise of Pure Cultures 1 causative agents of disease (etiology)
Simple staining techniques
First photomicrograph of bacteria
First photomicrograph of bacteria in diseased tissue
Techniques for estimating CFU/ml
Robert Koch (1843–1910) Infectious Disease, and the Rise of Pure Cultures 2 steam to sterilize media
Petri dishes
Aseptic Techniques to transfer bacteria
Bacteria as distinct species
Robert Koch (1843–1910) Infectious Disease, and the Rise of Pure Cultures 3 Microbial growth: Began with potato slices, but eventually devised uniform and reproducible nutrient solutions solidified with gelatin and agar
1970 Discovery of restriction enzymes
1980 The invention of the PCR technique
2000 The importance of small RNAs

2010 The role of the human microbiome
Molecular Microbiology: Fueled by the genomics revolution
Genomics: study of all of the genetic material (DNA) in living cells
Genetic Engineering: manipulates the genetics to create new products useful products (insulin)
Recombinant DNA technology:

transfer of genetic material from one organism to another and deliberately alter DNA
Chemotherapy Penicillin, sulfa drugs, antibiotics
Environment: Environment: Role of microbes in biofuel production and bioremediation (cleaning up pollutants)
Food: Negative impacts Food spoilage by microorganisms
requires specialized preservation
Food: Positive impacts Microbial transformations (typically fermentations) yield
dairy products (e.g., cheeses, yogurt, buttermilk)
other food products (e.g., sauerkraut, pickles, leavened breads, beer)
Nomenclature: Naming living things appropriately
Taxonomy: The science of classifying living beings
Phylogeny: The taxonomic scheme that represents the natural relatedness between groups of living things
Carl Woese and George Fox: Studied the small subunit of the ribosome (rRNA) to find genetic relatedness between organisms
Binomial system: A combination of the genus and species name
genus name = capitalized
species = lower case
Both names should be italicized when in print or underlined when written by hand
Abbreviations: The genus name can be abbreviated to save space or if the genus name has already been stated.

Example: Staphylococcus aureus can be abbreviated S. aureus

Louis Pasteur quote “The role of the infinitely small in nature is infinitely large”