Chapter 1: The Microbial World and You Flashcards
Define human microbiota and explain its role in human health
Human microbiota plays a large role in human health, for example, E. coli in the stomach acid aids digestion and synthesizing vitamins. Human microbiota also helps to prevent pathogenic bacteria from colonizing within the body.
Describe the characteristics of bacteria
unicellular, cell wall made of peptidoglycan, reproduces via binary fission
Describe characteristics of archaea
unicellular, mostly prokaryotes, cell wall NOT made of peptidoglycan, often extremophiles, not known to cause infectious disease
Describe characteristics of fungi
eukaryotes, multi or unicellular, cell wall made of chitin, yeast & mold
Describe characteristics of protozoa
eukaryotes, NO CELL WALL, move using pseudopodia, cilia, or flagella, can be free living or parasitic
Describe characteristics of algae
eukaryotes, cell wall made of cellulose (think about plants cell walls), photosynthetic
Describe characteristics of viruses
acellular (no cellular structure), very small, nucleic acid genome, capsid, sometimes has a lipid membrane envelope, repro. via other cells’ machinery (strictly parasites), considered not alive
List the three domains of life
Bacteria, Archaea, and Eukarya
eukarya= eukaryotes
Explain the importance of the observations of von Leeuwenhoek and Hooke
Hooke was the first to be able to see cells which started the cell theory; that all organisms are made of cells. Leeuwenhoek’s development of a high-powered microscope allowed him to see microbial cells and he drew them. His observations lead to debates over spontaneous generation of microbes or the theory of biogenesis- living cells only arise from other living cells.
Describe the experiments that provided support to biogenesis and discredited spontaneous generation
To disprove the theory of spontaneous generation, scientist Lazzaro Spallanzani sealed some chicken broth and heated it where he observed no microbes. However, some argued that due to the sealing, there was prevention of a “vital force” (oxygen) getting in. So, Louis Pasteur designed the swan-neck flask to avoid this problem. In his first experiment, he added the broth to an open flask, sterilized it by heating, let it sit for a few days and he observed microbes under a microscope. In his second and third experiments, he sealed the flask in one experiment resulting in no cells. In the other, he put the broth into a swan-neck flask, followed the previous steps, and still observed no cells. Thus, proving that cells can only develop from other living cells aka the theory of biogenesis.
Explain the Germ Theory of disease and the contribution of Koch’s postulates
The Germ Theory of disease is the idea that microbes cause infectious disease. Robert Koch discovered while dissecting an animal with anthrax rod-shaped bacteria in its blood. He collected some of the cells and grew them in the lab and then used them to inoculate another animal. when observing the newly infected animal he observed the same shaped bacteria in its blood. He developed 4 postulates that are steps for how to link a disease with the microbe that is responsible for said disease.
Describe how Jenner developed the first vaccine
Scientist Edward Jenner had noticed that milkmaids rarely developed smallpox but would have a milder form called cowpox. He hypothesized that somehow the development of cowpox prevented the development of smallpox. He tested this by scraping some pus from an infected individual and inoculating a young volunteer. The volunteer developed cowpox but was immune to smallpox. It was determined that cowpox is caused by a very similar virus that causes smallpox. The similarity between the 2 allows for the immune system to be trained against smallpox.
List Koch’s postulates
1) The same microbe must be present in every infected individual and absent in healthy individuals
2) The microbe must be grown from a pure culture by isolating the microbe from the diseased host
3)The microbe from the pure culture must cause disease when it’s inoculated into a healthy lab animal
4)The microbe must be isolated from the inoculated animal and shown to be the original microbe
Describe how Fleming discovered antibiotics
In 1928, Fleming was studying S. aureus and left for a week with some cultures still on his bench. When he returned, he saw that mold had grown on the cultures however, he noticed that the S. aureus colonies would not grow near the mold. Fleming hypothesized that the mold was releasing something that prevented the bacteria from growing. After isolating the compound, he called it penicillin.
List ways in which microbes are beneficial to humans
aid in digestion, prevent pathogenic bacteria from colonizing, produce mucous, protect stomach lining
Define and differentiate between “infectious disease” and “pathogen”
“infectious disease” describes a disease that is acquired from a disease-causing microbe. A pathogen IS the disease-causing microbe
Explain why pathogens cause disease
Since pathogens are parasitic, they infect the host and proceed to use resources inside of the host due to perfect environmental conditions which in turn damages the host. Pathogens also want to find a way to infect more organisms, so they come with symptoms that increase their chance of infecting a new host.
