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7/27/2019 Biology - Microbes
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Microbes and
biotechnology
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F.1 Diversity of microbes
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The Three Domains
Eubacteria: true bacteria. Prokaryotes with no organized nucleus
and no membrane-bound organelles. Example: Escherichia coli
which is commonly found in animal waste products.
Archaea: ancient bacteria and are also prokaryotes. Most groups
live in extreme environments. Example: sulfur bacteria which
inhabits the hot springs of Yellowstone National Park in the US.
Eukarya: single-celled and multicellular organisms which all have
their DNA contained in a nucleus. Plants, animals, protists, and
fungi belong here.
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Reasons for Reclassification into Three Domains
The five-kingdom system was inaccurate.
Use rRNA as a basis for reclassification of the three domains.
Use rRNA because it is a molecule common to all organisms.
Perform the same function (making up the subunits of ribosomes).
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Characteristics of the Three Domains
Eukarya Archaea EubacteriaHistones: Protein cores aroundDNA. Keeps DNA fromtangling when cell is dividing.
Histones-likeproteins.
No histones.
Introns: Non-coding areas ifDNA. Do not carry any
messages.
Only present insome DNA.
No introns.
Ribosomes: Where proteins aremade. Made of rRNA. 80Sribosomes
Small subunits ofribosomes. 70Sribosomes.
Small subunits of ribosomes.70S ribosomes.
Cell membrane: Includeunbranched hydrocarbons.
Some of thehydrocarbons are
branched.
Cell membrane: Includeunbranched hydrocarbons.
Only plants and fungi has cellwalls.
Has cell wall. Nopeptidoglycan.
Has cell wall. Peptidoglycan isfound in the cell wall.
Has many membrane-boundorganelles.
No membrane-bound organelles.
No membrane-boundorganelles.
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Diversity of habitat of Archaeabacteria
Methanogens: Use carbon dioxide to make methane. Killed by oxygen.
Live in the guts of termites and cattle, Siberian tundra, swamps, rice
fields, and in the large intestine of dogs, pigs, and humans.
Thermophiles: Live in sulfur hot springs with pH between 1 and 5 and
temperatures are up to 90 C. Some live where optimal temperatures
are up to 105 C.
Halophiles: live in the saltiest places in the world (Dead Sea, the Great
Salt Lake, evaporated salt water ponds). The salt content where they
live is ten times higher than salt content of the ocean.
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Diversity of Eubacteria
Spheres (cocci): Singly, in pairs, in a chain, or in a cluster.
Staphylococcus: A group of cocci clustered together. Caused skin
infections. Streptococcus: A row of cocci. Caused throat infections.
Rods (bacilli): Singly or in a chain. Streptobacillus: A row of bacilli.
Streptobacillus: A row of bacilli. Helices (spirilla)
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Comparison of Gram-positive and Gram-negative bacteria
Cell wall structure Gram-positivebacteria
Gram-negative bacteria
Complexity Simple Complex
Amount ofpeptidoglycan
Large amount Small amount
Peptidoglycanplacement
In outer layer ofbacteria
Covered by outermembrane
Outer membrane Absent Present withlipopolysaccharidesattached
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Diversity of structure of viruses
Virus is not considered as a living thing since a virus cannotreproduce without the mechanism of another organism.
Basic structure of virus:
Nucleic acid (genetic material) Enzymes Protein coat
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Diversity of microscopic eukaryotes
Organism Nutrition Locomotion Cell wall Chloroplasts
Cilia orflagella
Saccharomyces Heterotroph Absent Made ofchitin
Absent Absent
Amoeba Heterotroph Slides usingpseudopodia Absent Absent Absent
Plasmodium Heterotroph Glides onsubstrate
Absent Absent Absent
Paramecium Heterotroph Swimming Absent Absent Cilia
Euglena Autotrophandheterotroph
Swimming Absent Present Flagellum
Chlorella Autotroph None Made ofcellulose
Present Absent
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F.2 Microbes and the Environment
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The Nitrogen Cycle
Bacteria convert nitrogen into ammonia Nitrification: Change ammonia intro nitrites. Change nitrites
intro nitrates (oxygen is needed) Use active transport to transport nitrates into the roots of the
plant Assimilation: Plants use nitrates to make proteins. Animals feed
on plant and make their own protein. Plants and animals die and excrete. Waste products and dead
bodies contain molecules of nitrogen. Putrefaction: decomposers break down complex protein then
release nitrogen. Denitrification: Bacteria remove nitrites and nitrates.
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Release of raw sewage and nitrate fertilizer intorivers
Pathogen could be found by releasing raw sewage into water
systems.
Disasters proceeding excess nitrates and phosphates in water
systems:
Fertilize the algae in the water
Increased growth of algae
Algae are decomposed by aerobic bacteria which use up the
oxygen in the water.
Water becomes low in oxygen and organisms which need oxygen
will die.
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Production of biofuels