Top Ten Reasons that Biology 211 Students Think itʼs BORING to Learn About Organisms that You Canʼt Even SEE Without a Microscope

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1 Announcements There are NO assignments for points in this class on Mastering Biology - this is intended as a study resource for you Powerpoint files are in the Learning Modules on WebCT Exam over Unit 1 will become available on 15 September Top Ten Reasons that Biology 211 Students Think itʼs BORING to Learn About Organisms that You Canʼt Even SEE Without a Microscope 10. If itʼs that much work to just look at something, I donʼt want to know about it. 9. because itʼs information the average person doesnʼt need to know 8. I think those objects that canʼt be seen with a naked eye donʼt exist, i.e., theyʼre FAKE & made up things 7. You canʼt actually see them. (Reality) Only virtually. 6. It doesnʼt seem like those little organisms affect me. 5. because they are all similar looking and gross 4. because they have big words associated with them that I donʼt always understand 3. Because they are small, simple & do not really do anything 2. They arenʼt as interesting as maybe a cougar or a snake and theyʼre complex 1. because you canʼt point them out to others without a microscope Alternative Views - I have to be honest, I donʼt think itʼs boring at all. I love it! - It actually fascinates me how something so small and invisible to the naked eye can be so destructive. Yeah, I guess Iʼm kind of a geek. - I donʼt think itʼs boring to learn about tiny organisms because itʼs a necessity for the career I now have as a nurse and for the career I plan to have someday as a doctor

2 Theyʼre little and theyʼre (almost) everywhere!! The Prokaryotes Important Concept Prokaryotes are quite numerous How many prokaryotic cells are present in your mouth? Million Million 3. 1 Billion Billion Billion Estimated to be more bacteria in your mouth than all the humans who have ever lived i.e., > ~ 100,000,000,000 [100 billion] according to the Population Reference Bureau Your body has ~ 10X more bacterial cells than human cells How many distinct prokaryotic species are known to be present in the human mouth? , , ,400 About 400 distinct bacterial species known to be present in the human mouth 500 to 1,000 known to be present in the human intestine

3 Essential to ALL life on Earth (including YOURS) Minority of known species cause diseases in animals (including humans) and plants Found in very diverse habitats Some species are able to tolerate remarkable environmental extremes Extreme Prokaryotes Deinococcus radiodurans - can survive exposure to 3 million rads of radiation - 3,000 times the amount required to kill a human Picrophilus oshimae - can grow at ph acidic enough to dissolve metal Prokaryote Morphology Prokaryote Shapes (27.2) Most are unicellular Some colonial species A few have simple multicellularity Three common shapes: - spheres (cocci) - rods (bacilli) - spiral (spirilla) Prokaryote Cell Size Generally smaller than eukaryotic cells, but there are exceptions Typical eukaryotic cell size Fig Exceptionally small eukaryotic cells Typical prokaryotic cell size Prokaryote Motility About one half of all known prokaryotic species are motile The most common mechanism for motility is the prokaryotic flagellum Some can move as fast as 50 times their body length per second Equivalent to a human running the length of a pointy-ball field in ONE second! (~ 190 mph)

4 Prokaryotic Nutritional Modes (Table 27.1) Chemoautotrophs Some prokaryotic species live in association with Pogonophoran worms surrounding deep-sea thermal vents Oxygen - Not everything needs it Prokaryote species vary with respect to their use of oxygen in metabolism: - Obligate aerobes (this is what we are) - Obligate anaerobes (poisoned by oxygen) - Facultative anaerobes (can use oxygen, if available, but donʼt require it) Ecological Roles Chemical recycling - i.e., many prokaryotes are decomposers Symbioses - e.g., nitrogen fixation, digestion of cellulose, bioluminesence Bioluminescent Fish (27.20) Photoblepharon palpebratus flashlight fish Flashlight Fish Blue Planet - The Deep: Headlights - 16:00 Organ containing bioluminescent bacteria

5 Prokaryote Phylogeny About 6,300 species named BUT - estimates indicate that a single handful of soil might contain 10,000 distinct species of prokaryotes Nucleotide sequences have proven to be quite useful in beginning to have a better understanding of prokaryotic diversity - but weʼve got a LOT left to learn Two Domains of Prokaryotes Fig Carl Woese Person responsible for first recognizing the fundamental distinction between Bacteria and Archaea WebCT Question What prompted Woese to create the three domains used for classification and how did he get to this conclusion? Evidence for two Domains of Prokaryotes: Comparison of ribosomal RNA sequences among various prokaryotes Table 27.2 Archaea share some features with bacteria and some with eukaryotes (cells with nuclei) Table 27.2

6 What is a clade? Prokaryote Diversity A group of related organisms Can be at any taxonomic level (i.e., a Genus is a clade, an Order is a clade, a Domain is a clade) Clade is often used when there is not agreement amongst biologists regarding what taxonomic level a particular group of organisms should be assigned Domain Archaea Many, though not all, species of Archaea live in extreme environments Four Clades (Kingdoms?): Euryarcheotes Crenarcheotes Korarcheotes Nanoarcheota Clade Euryarcheota All known methanogens, many halophiles, some thermophiles Methanogens Metabolism leads to production of methane (CH4) Live in anaerobic ( no O2) environments e.g., swamps and marshes, guts of some animals O2 is poisonous to these organisms - they are obligate anaerobes Methanogens Aiding herbivores (e.g., bison, termites) in the digestion of cellulose Sewage treatment Conversion of garbage to methane

7 Salt lover Extreme Halophiles May require an environment 10 times saltier than sea water for growth Found in the Great Salt Lake and Dead Sea Ponds used for salt production Salinity of 15-20% Bacteriorhodopsin Extreme Halophiles Extreme Thermophiles Clade Crenarcheota Most thermophiles Heat lover Grow optimally in high temperature environments o C Often metabolize sulfur Extreme Thermophiles Not all members of the Domain Archaea are extreme Recent studies have found euryarcheotes and crenarcheotes in environments including farm soils, lake sediments, and surface waters of the ocean Geyser in Nevada (Fig )

8 Domain Bacteria Includes most named (i.e., currently known to science) prokaryotes Most have peptidoglycan in their cell walls Peptidoglycan not present in archaean cell walls Bacteria Five major clades (Kingdoms?) (Fig ): Proteobacteria Chlamydias Spirochetes Cyanobacteria Gram-positive bacteria Proteobacteria Bdellovibrio - a tiny predator Most diverse group All types of nutritional modes represented Photosynthesis, when present, doesnʼt produce oxygen Escherichia coli, Salmonella spp., Agrobacterium spp., Vibrio cholerae Symbiotic Nitrogen Fixation Rhizobium (Fig ) Chlamydias Obligate intracellular parasites Lack peptidoglycan in their cell walls Chlamydia trachomatis most common cause of blindness world-wide most common STD - nongonococcal urethritis - in the USA

9 Spirochetes Lyme Disease (Fig ) Chemoheterotrophs Can be quite long (0.25 mm) Treponema pallidum - cause of syphilis Borrelia burgdorferi - cause of Lyme disease Cyanobacteria Pond scum ; pond moss Photoautotrophs Produce oxygen during photosynthesis like plants and photosynthetic protists ( algae ) Single-celled and colonial species Some fix nitrogen Announcements Did you leave your clicker in class on Thursday? One was turned in to me. Seminar of potential interest: Dr. Robert Constanza (University of Vermont) Ecological Economics: Creating a Sustainable and Desirable Future Thursday 11 September, 7:00 PM, Great Hall, Memorial Union What makes farts smell? Biology you can USE! Sulfur containing compounds such as hydrogen sulfide gas and mercaptans Nitrogen containing compounds such as skatole and indole

10 How do we produce these chemicals? Ethyl mercaptan Benzyl mercaptan Furfuryl mercaptan Trick question - WE donʼt, the prokaryotes living in our large intestine do Skatole Indole Why do some peopleʼs farts smell worse than others? Depends on: What theyʼve been eating - sulfur-rich foods (e.g., eggs) produce the worst smelling farts What particular species of prokaryotes inhabit their large intestine So.. Itʼs NOT your fault - itʼs the fault of the prokaryotes living inside of you! Organisms you canʼt see without a microscope effect every one of us Cyanobacteria Anabaena (Fig ) Anabaena Quite independent: carries out photosynthesis (i.e., obtains carbon from CO 2 the air) fixes nitrogen (i.e., obtains nitrogen from N 2 in the air) in its heterocytes

11 Nostoc - Another Genus of Cyanobacteria Sometimes turns Lake LaVerneʼs water green... Gram-positive Bacteria Most are chemoheterotrophs Clostridium, Mycobacterium, Streptococcus Some produce resistant endospores Bacillus anthracis (Fig. 27.9) Gram-positive Bacteria Mycoplasmas smallest known cells lack cell walls walking pneumonia Actinomycetes sources of antibiotics (e.g., streptomycin) Mycoplasma (Fig 27.18) Bacteria for Dinner? I found prokaryotes to be More boring than I thought possible 2. About as dull as I expected 3. About as interesting as I expected 4. Far more interesting and diverse than I imagined