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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