L1-Intro to microorganisms Flashcards
Explain 3 ways that microorganisms are central to our world.
1–Oxygen is produced by microbial activity
2–Microbes are used in production of antibiotics and human proteins
3–They recycle key nutrients and degrade matter
How did the evolution of bacteria change the world?
--First 2 billion years-surface of earth was mainly composed of N2, CO2, and a few other gasses (anoxic/O2 absent) First phototrophs develop (eg. Purple bacteria) and they are anoxygenic (photosynthesize but don’t produce oxygen) Oxygenic phototrophs (eg. Cyanobacteria) evolved and oxygenated the atmosphere This eventually lead to the support of multicellular life (aerobic respiration=more ATP
Describe at least five environments in which microbes exist and what they contribute to that environment
1) Nodules on roots of legumes-bacteria convert atmospheric nitrogen (N2) into ammonia, which plants use as a nitrogen source for growth.
2) Rumen of ruminant animals (eg. Cattle, sheep etc.) microbes digest and ferment cellulose at neutral pH. Give more nutrients to the animal
3) foods-Dairy products depend on microbe activities/fermentation (ex. Cheeses, yogurt and butter). Baked goods and alcoholic beverages rely on fermentation of yeast which generates CO2.
4) feedstocks such as sugarcane or cornstarch-microbial fermentation of glucose creates biofuels
5) swamps-anaerobic degradation of organic matter creates natural gas (methane
How did the Pasteur flask revolutionize microbiology?
–It was used to disprove the belief of spontaneous generation (organisms sprung from nonliving materials)
Experiment:
–Poured nonsterile liquid into flask, flask neck extended with heating. Liquid was sterilized by heating
–Liquid cooled slowly and dust and microorganisms became stuck in the bend. Liquid could remain sterile indefinitely
–If the flask is tipped, then the liquid putrefies/organisms grow
What were the top cases of death in 1900 vs. today? Why?
Infectious diseases were the leading causes of death in 1900. However, today infectious diseases are less deadly/there is better control due to increased understanding of disease processes, improved sanitary and public health practices, and use of antimicrobial agents (ex. Antibiotics). Today, nonmicrobial diseases are the leading causes of death.
What are Koch’s postulates?
1) CORRELATION-The disease-causing organism must always be present in animals suffering from the disease but not in healthy animals
2) CULTIVATION-The organism must be cultivated in a pure culture away from the animal body
3) CAUSATION-The isolated organism must cause the disease when inoculated into healthy susceptible animals.
4) VERIFICATION-The organism must be isolated from the newly infected animals and cultured again in the library, after which it should be seen to be the same as the original organism.
What is a pure culture? How do you obtain a pure culture? Why is it important to obtain a pure culture?
A pure culture-A culture containing a single type of microorganism
To obtain a pure culture, you streak a sample on a plate and isolate a colony.
It is important to obtain a pure culture to definitively say that microorganism is causing the disease
Describe all the lines of evidence that Robert Koch used to associate Mycobacterium tuberculosis with the disease tuberculosis.
Koch found blue, rod-shaped cells of M. tuberculosis in tubercular tissues but not in healthy tissues
M. tuberculosis was cultured and isolated on agar plates
M. tuberculosis readily infected healthy guinea pigs
Cultures from lung samples of these infected guinea pigs transmitted the disease to other uninfected guinea pigs. Cultures from these animals showed M. tuberculosis.
Why is it difficult to apply all of Koch postulates to modern day medical microbiology?
Lack of an animal model for the disease Some diseases (such as rickettsias and chlamydias) only live within cells
How did Koch’s postulates influence the development of microbiology?
How did Koch’s postulates influence the development of microbiology
Koch’s postulates are now considered the “gold standard” in medical microbiology in linking a microorganism with a disease. However, it has been impossible to satisfy all of his postulates for every human infectious disease.
What important contributions of Beijerinck and Winogradsky revolutionized our understanding of microbial diversity?
Beijerinck-Enrichment culture technique-microorganisms can be isolated from natural samples by adjusting nutrient and incubation conditions to favor a particular metabolic group of organisms.
Winogradsky-chemolithotrophy-organisms use this process-oxidation of inorganic compounds (ex. to make energy/ATP and reducing power/NADH)-to yield energy. Also, bacteria are autotrophs like plants.
Beijerinck-Enrichment culture technique-microorganisms can be isolated from natural samples by adjusting nutrient and incubation conditions to favor a particular metabolic group of organisms.
Winogradsky-chemolithotrophy-organisms use this process-oxidation of inorganic compounds (ex. to make energy/ATP and reducing power/NADH)-to yield energy. Also, bacteria are autotrophs like plants.
Rapid progress in DNA sequencing technology, increased computational power and other advances in genomics has stimulated new subdisciplines of molecular microbiology: transcriptomics, proteomics, and metabolomics.
