Exam 1 Flashcards
what is a microbe?
a microbe is a living organism that requires a microscope to be seen (most diverse group of science)
- viruses are grouped with microbes because they infect all forms of life
examples of microbes
bacteria, archea, and eukaryotes (fungi algae, protozoa)
Where are microbes found?
everywhere! hydrothermal vents, salines, arctic marine sediment
why is the human microbiome useful?
digestion, to see good from bad
why study microbes?
they have shaped human culture since our earliest civilizations
positively: microbes produce 50% of the world’s oxygen and all its fermented foods (bread, beer, cheese)
negatively: disease that causes death and suffering
how do we know about microbes?
most knowledge was accumulated after 1900, driven by advances in microscopy and molecular techniques
application of microbes in environmental health
knowledge: microbes are key players in most elemental cycles
manage: use of microbes in biodegradation of pollutants, wastewater treatment plants
application of microbes in health
knowledge: microbes supply essential nutrients to hosts, but can also cause disease
manage: fighting infectious disease managing microbiome for better health
application of microbes in industry
knowledge: microbial metabolism can enrich and spoil foods
manage: use/control microbes in food, medicine and biofuel production
louis pasteur (pasteurization)
broth was boiled to kill all microbes, after a year, none appeared.
the flask was tipped to allow the broth to reach the microbes, microbes quickly multiplied
(showed microbes were not appearing out of nowhere, disproved spontaneous generation)
culture independent approach: sequencing
data led to identify domains:
bacteria
archaea (first life on earth)
eukarya
bacteria + archaea = similar membrane composition
archaea + bacteria = no nucleas, gene expression machinery
germ theory of disease
many diseases are caused by microbes
central dogma: Koch’s postulates
ability to isolate and culture bacteria is essential
koch’s postulates
ordered set of criteria for establishing a causative link between an infectious agent and a disease
1. suspected microbe is always present in disease hosts and absent in healthy hosts
2. suspected microbe is grown in pure culture outside hosts - no other microbes present in culture
3. cultured microbe is introduced into healthy hosts- individuals become sick with same disease as original hosts
4. same microbial suspect is re-isolated from sick individuals
Edward jenner
typically credited with developing first vaccination approach: deliberately infected patients with material he collected from cowpox lesions
lady Mary Mantagu
introduced the practice of smallpox inoculation to Europe in 1717, learned from people in Turkey and Africa
Lynn Margulis
proposed that eukaryotic organelles, such as mitochondria and chloroplasts, evolved by endosymbiosis from prokaryotic cells engulfed by preeukaryotes (mitochondria)
why was the endosymbiosis theory highly controversial?
implied more complex ancestry of living species through lateral exchange of genetic material, instead of vertical decent with modification
microscopy has revealed:
- Earth is a microbial world. There are no unexpected places…
- We are just as microbial as we are human
- Bacteria are beautiful!
why bother observing microbial cells?
to understand why these organisms cause these phenomena, a closer look can help
to understand how microorganisms interact with each other
size at which objects can be distinguished depends on…
density of photoreceptors of observer’s eye
resolution
the smallest distance by which two objects can be separated and still distinguishes
human eye
about 100-200 µm resolution
detection
ability to determine the presence of an object
magnification
an increase in the apparent size of an image to resolve smaller separations between objects. we can detect microbes in a culture or environment, but only resolve single cells by magnification (see separated from one another)