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BIOL 1353 Midterm: Exam 1 Review

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BIOL 1353
Study Guide

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Exam 1 Review
A. Chapter 1 (The Microbial World)
a. Defining what a microbe is
i. What are they? How are they defined? Microbial size ranges. What are
generally not considered microbes? Where are they found? Where did they
come from? Who discovered them? etc.
Microbes are also called microorganisms and are minute living things that
individually are usually too small to be seen with the unaided eye. This includes
bacteria, fungi, protozoa, viruses, and microscopic algae.
Eukaryotic Microbes 20-100m
Prokaryotes 1-10m
Viruses 0.02-0.9m
Antoine van Leeuwenhoek was the first to observe single-celled microbes
Microbes are found everywhere
ii. Origins: when did microbes evolve?
b. Taxonomic groupings: microbes in Domains Bacteria & Archaea (both are
prokaryotes), Domain Eukarya fungi, algae, protozoans
i. Classifying microbes - Kingdom System (historical: from 2 to 3 to 4 to 5 to 6
Kingdoms, now all in 3 Domains
1. Kingdom Protista (once contained all microbes) prokaryotes removed
from Protista and become Kingdom Monera (all prokaryotes); Protista
retains eukaryotic microbes only
2. Domains: based on comparison of 16S ribosomal RNA genes 3
domains (Eukarya, and two prokaryote domains Archaea & Bacteria
ii. Features of: bacteria & archaea; fungi (molds & yeast); protists (protozoa &
Bacteria: lack a nucles, no organellses, similarity in gene structure, metabolism
and environmental niches. Cell wall contains peptidoglycan. They also derive
nutrition from organic or inorganic sources or conduct photosynthesis
Archaea: extremophiles. Not typically associated with human disease.
Prokaryotes, and cell walls lack peptidoglycan. Thermophiles grow and live in
extreme temps of 70-110C. Methanogens produce methane gas, are anaerobic,
and are found in sewage plants, bogs, and intestinal tracts of ruminants.
Halophiles require NaCl, aerobic, and grow photosynthetically
Fungi: eukaryotic, can be unicellular or multicellular. Cell wall composed of

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Protozoa: unicellular eukaryotic microbe. Move by pseudopods, flagella, or cilia.
Live as free entities or parasites
iii. Similarities & differences: eukaryotic & prokaryotic cells
Eukaryotes: larger, has a nucleus, has organelles. Reproduces sexually or
asexually. There are unicellular and multicellular types. Fungi and protists fall
under this category.
Prokaryotes: do not have a nucleus or organelles. Single circular chromosome.
Reproduces asexually. Tend to have non-cellulosic cell walls. Diverse metabolic
types. Bacteria and archaea fall under this category.
iv. Viruses: features
RNA or DNA containing acellular particles; require host cell. Viruses take over
host metabolism to replication. Can only be seen with an electron microscope.
Core is surrounded by a protein coat
c. Impact of microbiology on our lives
i. Ecology, public health, biotechnology, knowledge of cell biology and genetics
The knowledge of life’s basic processes came from studying microbes
Biotechnology: recombinant DNA tech, applications in agriculture, textiles,
medicine, food production, chemical industry, energy
Ecology: the study of the relationship between microorganisms and their
ii. Benefits of microbes: advances in biotechnology, agriculture,
energy/environment (bioremediation), water treatment, human
Bioremediation: bacteria can be used to remove toxins from underground wells,
chemical spills, toxic waste sites, and oil spills. Also used to in drain cleaners to
remove clogs
Biotechnology has led to gene therapy. Also in agriculture, altered strains of
bacteria have been developed to protect fruit from insects and frost and drought.
Sewage treatment plants use microbes to convert liquid and organic products into
carbo dioxide, nitrates, phosphates, sulfates, ammonia, and methane.
d. Historical perspective of microbiology
i. Microscopy: van Leeuwenhoek, Hooke
Robert Hooke was the first to report life’s smallest structures (cells).
Leeuwenhoek used a higher magnification microscope and found microbes.
ii. Spontaneous generation

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The idea that some forms of life could arise spontaneously from nonliving matter
iii. Pasteur’s contributions disproved spontaneous generation; germ theory of
He used a swan-neck design that excluded dust and microbes, but allowed entry
of air. Growth only occurred when contaminated. This showed that microbes are
present in non-living matter; food spoilage. Led to later development os aseptic
iv. Robert Koch’s contributions: pure culture technique, Koch’s postulates;
Germ Theory of Disease
Koch was the first to establish scientific principles for linking a specific microbe
to a specific disease; in the process he established a chain of infection. He did this
v. Immunization & vaccination; concept of immunity; attenuation (attenuated
Vaccinations: protect individual against disease by inoculation with a less virulent
form of the pathogen -> basis for attenuation
Attenuated vaccines are created by reducing the virulence of a pathogen but still
keeping it viable
Smallpox vaccination, 1790s -> Edward Jenner (cowpox)
Pasteur: attenuated vaccines for fowl cholera and rabies
vi. Chemical & physical agents of control: Antiseptics/disinfectants - how do
they differ? Synthetic drugsDiscovery of antibiotics
Antiseptics are used to kill microorganisms on living things. Disinfectants are
used to kill microorganisms on nonliving surfaces like countertops.
Synthetic drugs: discovered by Elrich on accident as he was looking for a “magic
bullet” and found an agent against syphilis. A synthetic drug is a chemical
compound produced in a lab
Antibiotics are produced naturally by many microbes. Discovered by Alexander
Fleming in 1929; penicillin. Gotta be careful bc of antibiotic resistance
vii. Microbial ecology: importance of microbes in ecosystems & geochemical
cycling; autotrophs, heterotrophs, lithotrophs; nitrogen cycle; decomposition
Normal Microbiota are generally harmless microbes that live on and in our
bodies. We share a Commensalistic and mutualistic relationship with our
Microbes play a huge part in ecology. Prokaryotes are especially important in
converting inorganic and organic forms of N, S, P, C, and other minerals into
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