MicroBio Mod. 1

How microorganisms effect humans:

Positive:

• maintain balanced in our environment

• decompose waste

• recycle chemical elements among the soil, water, other organisms, and the air

• photosynthesis

• synthesis of vitamins, organic acids, enzymes (which can be used to make insulin and proteins for vaccines), alcohol, and drugs.

• Produce industrial chemicals such as ethyl alcohol and acetone

• Produce fermented foods such as vinegar, cheese,

  and bread

Negative:

• only a small percent of microorganisms are harmful and can make us sick.

What percentage of all cells in the human

body are bacterial cells?

~ 56%

Human Microbiome (Microbiota)

Microbes that live stably in and on the human body

Normal Microbiota

Microbes indefinitely colonized in the body

Transient Microbiota

Microbes only temporarily part of the microbiome (fleeting member of the community)

Basis for scientific names

Each organism has two names:

• the genus (broader, closely related group of organisms)

• the specific epithet (exact species within the genus)

The genus is capitalized while the species name is not, and all are underlined or italicized.

Organims classification

• Bacteria (Prokaryote)

• Archaea (Prokaryote)

• Eukaryote - Fungi, plants, animals, protists, Algae

Prokaryotes: Bacteria

• peptidoglycan cell wall

• reproduce through binary fission

• use organic chemicals, inorganic chemicals, and photosynthesis for energy

• no nucleus or membrane-bound organelles

• single chromosome

Prokaryotes: Archaes

• lack peptidoglycan in their cell walls (if they have a cell wall, not all of them do)

• live in extreme environments

• Include methanogens, extreme halophiles (salt), and extreme thermophiles (temperature)

• no nucleus or membrane-bound organelles

• single chromosomes

Eukaryotes: Fungi, Plants, Animals, Algae, Protozoa

• most are multicellular

• multiple chromosomes

• internal membrane-bound organelles

Fungi

• chitin cell walls

• use organic chemicals as energy

• molds and mushrooms are multicellular consisting of masses of mycelia, composed of filaments called hyphae

• yeasts are unicellular

Algae

• use photosynthesis for energy

• produce molecular oxygen and organic compounds

Protozoa

• absorb or ingest inorganic chemicals

• may be motile via pseudopods, cilia, or flagella

Multicellular Animal Parasites

• multicellular animals

• parasitic flatworms and round worms are called helminths

• microscopic stages in life cycles

Viruses

• acellular

• consist of DNA or RNA

• core is surrounded by a protein coat

• coat may be enclosed in a lipid envelope

• viruses are replicated only when they are in a living host cell

Cell Theory

The theory that all living things are composed of cells and come from existing cells (Hooke’s discovery marked the beginning of this theory)

Hooke and Leeuwenhoek

• Hooke reported that living things were composed of little boxes, or cells

• Leeuwenhoek described live microorganisms that he observed in teeth scrapings, rain water, and peppercorn infusions.

Spontaneous generation vs biogenesis

Spontaneous generation:

• The hypothesis that living organisms arise from nonliving matter is called spontaneous generation. According to spontaneous generation, a “vital force’ forms life.

Biogenesis:

• living organisms arise from preexisting life

Experiment supporting Biogenesis!

• Louis Pasteur demonstrated that microorganisms are present in the air

• He had two flasks, one with heated nutrient broth that was sealed, and one with nutrient broth that was unsealed.

• The sealed flask had no microbial growth, suggesting that microbes don’t come from nothing

• The unsealed flask had growth, suggesting microbes are already present in the air

• Pasteur also has S-shaped flasks that he bent in such a way that air could still enter but microbes could not. The heated and cooled broth was left in the flasks for months with no signs of microbial growth, further proving his theory. (The bend in the necks trapped any microbes that may have entered in the air)

Needham’s contributions

• first to suggest spontaneous generation by finding that broth boiled, cooled, and placed into covered flasks was soon teeming with microorganisms

• claimed that the “vital force” necessary for spontaneous generation was destroyed by heat applied to the flask after sealing it, shutting down Spallanzani’s theory of biogenesis

Spallanzani’s contributions

• suggested microbes from the air had entered Needham’s flasks during his experiments for spontaneous generation

• he proved this by showing that broth heated after they were already sealed in flasks did not have ay microbial growth

Virchow’s contributions

• challenged the case for spontaneous generation with the concept of biogenesis, hypothesizing that living cells arise only from preexisting living cells.

• Wasn’t proven until a few years later by Pasteur

Pasteur’s contributions

• proving biogenesis

• fermentation (converting sugar to alcohol in the absence of air) and pasteurization: Pasteur discovered that bacteria are responsible for fermentation and food spoilage. He demonstrated that heating wine just long enough to kill the bacteria without evaporating the alcohol. This process was applied to many other things and called Pasteurization.

The Germ theory of Disease

• The idea that microorganisms cause disease

Pasteur’s Influence: Lister

• used a chemical disinfectant to prevent surgical wound infections after looking at Pasteur’s work showing microbes are in the air, can spoil food, and cause animal diseases

• proved that microorganisms can cause surgical wound infections

Pasteur’s Influence: Koch

• provided proof that a bacterium causes anthrax and provided the experimental steps, Koch’s postulates, used to prove that a specific microbe causes a specific disease.

• was Pasteur’s rival in the race to discover the cause of Anthrax and provided the first real proof that bacteria caused disease.

Koch’s Postulates

• were invaluable in investigations proving that specific microorganisms cause many diseases

Steps:

• culture the bacteria on nutrients

• inject into healthy subject

• once the subject becomes sick and dies, isolate the bacteria in the blood and compare it to the original isolated bacteria.

Steps from Google:

• Association: The suspected pathogen must be found in all cases of the disease and absent from healthy subjects.

• Isolation: The pathogen must be isolated from the diseased host and grown in pure culture.

• Inoculation: A healthy, susceptible host infected with the cultured pathogen must develop the same signs and symptoms of the disease.

• Re-isolation: The pathogen must be re-isolated from the new host and shown to be identical to the original pathogen

Jenner’s discovery

Vaccinations and Immunity:

• Observation: Dairymaids who had mild cowpox infections

  were protected from smallpox

  Hypothesis: Cowpox infection provides protection against

  smallpox

  Experiment (1798): Inoculated boy with cowpox fluid and

  later challenged with smallpox fluid

  Result: Boy did not get smallpox

  Called vaccination from vacca for cow

Ehrlich’s contributions

• jumpstarted the idea for modern chemotherapy by developing a synthetic arsenic drug, salvarsan, to treat syphilis.

• came up with the “Magic Bullet” which could hunt down and destroy a pathogen without harming the infected host.

Fleming’s contribution

• Discovered the first antibiotic, Penicillin

• noticed that some culture plates contaminated by mold had a clear area where bacterial growth had been inhibited encircling the mold.

• Became what know as Penicillin, and he used it to kill S. aureus.

• Today, it’s used to kill many types of bacteria

Bacteriology

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