Typed lecture notes covering chapter 1 of Microbiology: An Evolving Science, the textbook used in the "General Microbiology" course (BioM122) at UCI. Aligns with lecture 1.
Intro to Microbiology (Ch. 1, Lec1)
Friday, October 2, 2020 1:25 PM
• Microbes are diverse, ancient, and everywhere. 10/5/20 live lecture
• Bacteria and Archaea are microbes! Eukaryotes are the only ones no microbial. • Pastuer's expt: testing if there was something in the air (ie oxygen) that causes
○ Some single-celled eukaryotes called protists that are considered microbes. spontaneous generation. Purpose from curved flask was to prevent
microorganisms from entering the flask.
• Reading: chp1 in txtbk.
• Marine microbes first life forms on earth, dominated the planet for 2bil years. Ex. • *Resolution of a light microscope is limited by wave nature of a light.
Prochlorococcus produces oxygen via photosynthesis. ○ Smaller the wavelength, the smaller the objects need to be to be resolved.
• Sec1.1: Microbe: a living organism that requires a microscope to be seen.
○ Most consist of a single cell. Range from 0.2um to few mm.
○ Each microbe contains in its genome the capacity to reproduce.
• *Key postulates of microbial ecology: 1) microbes are found in every Earth environment, and
2) every molecule can be used by a microbe.
• Microbes include many different types of organisms:
○ Prokaryotes (cells lacking a nucleus): bacteria, archaea.
○ Some eukaryotes (cells w/ a nucleus): algae, fungi, protists.
○ Viruses and prions (acellular entities)
• Bacteria, archaea and eukaryote domains evolved from a common ancestral cell.
• Genome: comprises the total genetic info of an organism.
○ 1st DNA sequencing method fast enough to sequence large genomes developed by Fred
Sanger.
• Metagenomes: environmentally-derived collections of sequences from diverse populations of
microbes. Ex. Sequencing of gut tissue.
• A lot of genes within a genome is unknown in function.
• Microbial diseases: 14th century bubonic plague caused by Yersinia pestis. TB, AIDS, SARS-
COVID2.
• Spontaneous generation: theory that living creatures could arise w/o parents.
• **Pasteur produced data that refuted spontaneous generation-- swan-neck flask expt.
○ Showed that broth boiled in said flask remained free of microbial growth, despite being
exposed to air.
• 1.3: Medical Micro
• Germ theory of disease: many diseases are caused by microbes.
• **Koch: chain of infection/transmission of disease. Postulates established that infectious
agents cause disease.
1. Suspected microbe is always present in diseased hosts. (Absent in healthy hosts.)
2. Suspected microbe is grown in pure culture outside of hosts. (No other microbes present in
culture)
3. Culture microbe is introduced into healthy hosts. (Individuals become sick w/ the same disease
as orig hosts)
4. Same microbial suspect is re-isolated from sick individuals.
• Immunization: stimulation of an immune response by deliberate inoculation w/ an attenuated
pathogen.
• Penicillin mold generated a substance that kills bacteria; penicillin became first antibiotic.
• Lithotrophs: organisms that feed on inorganic material; discovered by Winogradsky.
• Ex of an endosymbiont: yeast cells in vaginal tract, bacteriode biofilms in digestive tract.
• 16S rRNA sequences show that archaea are as distant from bacteria as they are from
eukaryotes.
• Ex of archaea: single-celled organism that lacks a nucleus and cell walls are NOT composed
of peptidoglycan.
• Ruska-> built electron microscope. Svedberg-> built ultracentrifuge.
• Scientists that contributed to the structure of genetic material: Crick, Franklin, Watson, Griffith.
• CHAPTER SUMMARY
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