Ch 1 History Flashcards
What is a microbe?
Microbes are minuscule organisms that require a microscope to be seen
What are the major different groups of prokaryotic microorganisms?
Bacteria and archaea
What are the defining characteristics of bacteria?
- Some bacteria have been identified as pathogens
- Cell walls contain peptidoglycan
- Can be photosynthetic or not photosynthetic
What are the defining characteristics of archaea?
- They have not been identified as pathogens
2. Cell wall is made up of psuedopeptidoglycan
What are the similarities between archaea and bacteria?
- Both can grow in various environments (can also live in the human body)
- unicellular, prokaryotic organisms
What are the major different groups of eukaryotic microorganisms?
Algae, protozoa, fungi, helminths
What are the defining characteristics of algae?
- Can be multicellular or unicellular
2. Derive their energy from photosynthesis
What are the defining characteristics of protozoa?
- They are unicellular
- Have complex cell structures
- Can move either through extensions of their cytoplasm or cell membrane or with the help of cilia and flagella
What are the defining characteristics of fungi?
- Can be multicellular or unicellular (mold)
2. Cell wall is made up of chitin, not photosynthetic
Mold
Multicellular fungi that is responsible for decomposing dead plants and animals
What are the defining characteristics of helminths?
They are multicellular parasitic worms that cause disease.
- technically they are not microorganisms since they can be seen with the naked eye
Van Leeuwenhoek
He was the first scientist to create a lens that was powerful enough to see microorganisms.
He invented the first microscope and discovered the first microorganisms.
Pasteur
1) He showed that microbes caused fermentation, invented pasteurization, and developed vaccines for the treatment of some diseases.
2) His swan neck flask experiment helped him irrefutably disprove the theory of spontaneous generation.
Why was the bend in the swan neck flask important?
The neck prevented airborne microorganisms from entering the flask and contaminating the broth. This also allowed air from the inside to be exchanged with the outside while keeping the broth sterile.
What was the purpose of the flask that had the neck broken off?
It was used as a control to show that when airborne microorganisms have access to the broth in the flask, microbial growth would be seen in the flask.
Linneaus
He developed a new way to categorize organisms into different levels based on their similarities.
He also developed the naming system known as binomial nomenclature.
How have phylogenetic trees changed since Linnaeus?
More kingdoms were added by other scientists. Haeckel proposed having four kingdoms, adding protists and monera which were for unicellular organisms with a nucleus, and for unicellular organisms that lack a nucleus respectively. After, Whittaker proposed adding a fifth kingdom to the tree of life, fungi, which was considered the standard for years. Later, Woese would create a phylogenetic tree that categorizes organisms based on the similarity of their gene sequences.
What is the correct naming of an organism using binomial nomenclature?
A two-word name that classifies an organism by its genus and specific epithet.
- Genus must be capitalized
- Specific epithet is lowercase
- The whole name must be italicized (typing) or underlined (writing)
Woese
He created a phylogenetic tree based on the differences and similarities in the small subunit rRNA gene sequences of different organisms.
He discovered a level above kingdoms known as domains (bacteria, eukarya, archaea)
What specific sequence allowed Woese to make his significant discovery?
small subunit rRNA gene sequences
What was Woese’s significant discovery?
Archaea
How have gene phylogenetic trees changed how we think about species?
It helped show that archaea, bacteria, and eukaryotes all evolved from a common ancestral cell type. Instead of thinking in terms of trees of life, we now think in terms of webs of life as scientists discover how closely evolutionarily related organisms are.
Redi
He was one of the first scientists to refute the idea of spontaneous generation through his experiment with meat and the appearance of maggots.
What is spontaneous generation?
When life can be produced from nonliving matter
What is the purpose of the open container in Redi’s experiment?
The open container was used as a control to show that meat left in the open air formed maggots. This helped his experiment by demonstrating that the meat inside closed containers will not form maggots as they are not exposed to open air.
Semmelweis
He showed that handwashing was effective at preventing the transmission of diseases.
Snow
He fought against the idea that disease was only caused by contaminated air. He demonstrated that contaminated drinking water was the cause of transmission of the cholera bacteria in London.
What field did snow develop through his work?
epidemiology
Lister
He proved that using carbolic acid as a disinfectant was effective at preventing postsurgical infections. His discovery became standard practice to prevent infections after surgery.
Koch
He assigned pathogens to diseases.
What are Koch’s 4 postulates?
- A suspected pathogen should not be found in healthy individuals but must be found in people who have the disease. (association)
- The suspected pathogen needs to be isolated and grown in pure culture. (isolation)
- Inject the healthy test subject with the suspected pathogen grown in pure culture. They need to develop the same symptoms of the disease. (causation)
- Take another sample of the same pathogen from the host and re-isolate it. This shows that the suspected pathogen causes the disease. (reisolation)
Will all diseases fit Koch’s postulates?
No
What are some examples that won’t fit all 4 postulates?
1) Healthy carriers
2) Organisms that can’t grow in pure culture (viruses, some bacteria)
3) Reinfecting a new host (some diseases have not fulfilled Koch’s postulates)
Ehlrich
After screening hundreds of compounds, he discovered compound 606, known as salvarsan, that targeted treponema pallidum, the bacteria that causes syphilis. This was then used to treat the disease in people. His screening method is still used today.
Fleming
He discovered the first natural antibiotic, penicillin. Through his research, he found that penicillin effectively fought against and inhibited staphylococcal growth.
Jenner
Developed the process of vaccination. He noticed that people who had cowpox did not get infected with smallpox. He used cowpox to protect people from smallpox.
What are viruses?
They are acellular microorganisms (not composed of cells, are only made up of proteins and genetic material DNA or RNA)
Can infect all types of cells (responsible for numerous diseases in humans although, many viruses do not cause disease )
