Chapter 1- An invisible world Flashcards
Microorganisms/microbes
Very small organisms that are generally too small to see without a microscope (some parasites and fungi are exceptions). All microbes, even viruses and prions, can be considered forms of life even though they aren’t organisms
Fermented foods and beverages
Includes beer, wine, bread, yogurt, cheese, and pickled vegetables. Microbial fermentation is required to produce these foods. It can preserve or enhance the flavor of food
Microbial fermentation
A process that uses bacteria, mold, or yeast to convert carbohydrates to alcohol, gases, and organic acids
How did prehistoric people attempt to treat disease?
Through the use of fungi that had medicinal properties. There is some evidence that people made incisions filled with herbs and then burned the herbs to treat disease
When was quarantine used in ancient civilizations?
People with leprosy and some other diseases were often contained, indicating that people knew some diseases could be spread to others. However, leprosy progresses slowly, so people usually transmitted the disease before they were quarantined.
Miasma hypothesis
The Greeks and Romans believed that disease was caused by “bad air”, and their hygiene practices were based on this idea. The idea was that if the smell was sewage was present and people got sick, it was from the smell rather than contamination from the sewage. Also, lack of hygiene made people smell and this was thought to make people sick (due to the smell). The Romans built complex sanitation infrastructure, including aqueducts and sewers (including the Cloaca Maxima), also based on the miasma hypothesis. This may have protected them from waterborne illnesses
What did Hippocrates believe caused disease?
At the time, many people believed that disease was caused by supernatural forces. However, Hippocrates believed that diseases had natural causes from the patient’s body or the environment. Hippocrates wrote medical textbooks (the Hippocratus Corpus) and the Hippocratic Oath.
Thucydides
Greek philosopher- he advocated for evidence-based analysis of cause and effect reasoning. He demonstrated an early understanding of immunity by observing that survivors of the plague did not get re-infected.
Marcus Terentius Varro
Roman writer, was one of the first people to suggest that things we couldn’t see (microorganisms) could cause disease
Antonie van Leeuwenhoek
The first person to develop a lens powerful enough to view microbes in 1675. He was able to observe single celled organisms. He called them animalcules, although they were actually bacteria and protists.
Golden Age of microbiology
The time between 1857 and 1914, where there were many new discoveries in microbiology. This includes the findings of Louis Pasteur and Robert Koch
Louis Pasteur
Showed that individual microbial strains had unique properties. He also found that fermentation is caused by microorganisms. He invented pasteurization and developed vaccines to treat disease in animals and humans, including a vaccine for rabies
Pasteurization
A process used to kill microorganisms responsible for spoilage
Robert Koch
Demonstrated the connection between an isolated microbe and disease in humans. He discovered the bacteria that caused anthrax, cholera, and tuberculosis.
Microscopes
Produce magnified images of microorganisms, human cells and tissues, and many other types of specimens too small to be observed with the naked eye
Stains and dyes
Used to add color to microbes so they can be better observed under a microscope. Some dyes can be used on living microbes, while others require that the specimens be fixed with chemicals or heat before staining. Some stains only work on certain types of microbes because of differences in their cellular chemical composition.
Growth media
Used to grow microorganisms in a lab setting. Some media are liquids; others are more solid or gel-like. A growth medium provides nutrients, including water, various salts, a source of carbon (like glucose), and a source of nitrogen and amino acids (like yeast extract) so microorganisms can grow
and reproduce. Ingredients in a growth medium can be modified to grow unique types of microorganisms.
Petri dish
Flat-lidded dish that is typically 10–11 cm in diameter and 1–1.5 cm high. Petri dishes made out of either plastic or glass are used to hold growth media
Purpose of test tubes
Used to grow microbes in broth or solid/semi solid growth media
Microincinerators
Used for the same purpose as a Bunsen burner. They are generally replacing microincinerators because they don’t have the risk of an open flame
Inoculation loop
A tool that ends in a small wire loop. The loop can be used to streak microorganisms on agar in a Petri dish or to transfer them from one test tube to another. Before each use, the inoculation loop must be sterilized so cultures do not become contaminated.
Taxonomy
The classification, description, identification, and naming of living organisms
Classification
The practice of organizing organisms into different groups based on their shared characteristics
Carolus Linnaeus
Swedish zoologist and physician. He published Systema Naturae in 1735, which proposed the Linnaean taxonomy. This was a system of categorizing and naming organisms that scientists could use to name organisms with standardized terminology.
Linnaean taxonomy
Divided the natural world into animal, plant, and mineral kingdoms. Plant and animal organisms were grouped using a hierarchy of levels and sublevels based on their characteristics. The mineral kingdom was later removed
Levels in Linnaean taxonomy (6)
Kingdom, class, order, family, genus, species. Species is the most specific unit
Phylogenies
Evolutionary relationships between different species. Phylogenetic trees were used to depict these relationships. Modern phylogenic analyses include genetic, biochemical, and embryological comparisons
How did Linnaeus’ phylogenetic tree change over time?
His original tree contained 2 branches- plants and animals. Eventually, the kingdoms Protista were added for unicellular organisms, Monera for unicellular organisms whose cells lack nuclei (bacteria), and fungi. A superkingdom level was added to distinguish between eukaryotes and prokaryotes
Empire Prokaryota vs Empire Eukaryota
Distinguishes between organisms that have membrane bound nuclei and those that don’t. Prokaryotes only include the kingdom Monera, while eukaryotes include fungi, Protista, Plantae, and Animalia
Why aren’t viruses depicted in phylogenetic trees?
They aren’t made up of cells, so they don’t fit in any kingdoms
Why was the development of molecular genetics important to phylogeny?
It allowed for a standardized way to compare all living organisms without relying on observable characteristics, which can be subjective. Organisms are considered to be related if they have more similar nucleic acids and proteins
Carl Woese
In the 1970s, he created a phylogenetic tree based on gene sequences that coded for small subunit rRNA in different organisms. He discovered a type of bacteria called archaea was significantly different from other bacteria and eukaryotes based on its rRNA sequence. As a result, 3 domains were added above kingdoms- archaea, bacteria, and eukarya. These 3 domains evolved from a common ancestral cell type
