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BOT 2100 Lecture Notes - Lecture 15: Root Nodule, Nitrogenase, Root Hair

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blueelk163
13 Apr 2018
School
University of Guelph
Department
Botany
Course
BOT 2100
Professor
Ian Tetlow

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Document Summary

Plants can only take up and use n in certain forms. These forms interact with soil particles and symbiotic organisms. N-n triple bond is unusable by plants, but hold a lot of energy. Nitrogen is readily available and can be used when in n-containing compounds. Nh3 and nh4+ are usable forms of n that can be uptaken by plants. No2 and no3 can be used by most plants, but are often leached. In order for n and n2 gasses in the atmosphere to become useful to plants, they must be converted into organic ammonia via nitrogenase in an anaerobic environment. Pla(cid:374)ts attra(cid:272)t free li(cid:448)i(cid:374)g (cid:373)i(cid:272)ro(cid:271)es to (cid:271)uild a (cid:862)rhizosphere(cid:863) around their roots. Carbs and mucilage from root caps support bacterial growth. Once the n is generated, it is made available to the plant when amoeba and fungi feed upon it. To maximize uptake, roots maximize surface area, and so does the symbiotic bacteria.

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Related Questions


Class 6: Viruses (and Cells, continued)


Making connections: viruses and microbes Match the cell biology concept (on page 1) with an important application of that concept (on page 2). Then answer the follow-up questions at the bottom of page 2.


Cell Biology concepts
1. Bacteria that cannot construct new cell wall material become fragile and break down.
2. During influenza infection, the viral enzyme neuraminidase is required to release new viruses from the host cell in which they were made. Once released, the new viruses can infect many additional cells.
3. Thermus aquaticus is a bacterium found in hot springs and can live at temperatures up to ~80°C (175°F). It has adapted so that its enzymes are most functional at the elevated temperatures, compared with many organisms’ enzymes that function best ~37°C (98°F).
4. Until the isolation and investigation of retroviruses, scientists thought that RNA could be copied from DNA, but DNA could not be copied from RNA. Research on this class of viruses led to an update to this “Central Dogma” of biology.
5. Some bacteria have adapted, so that the enzymes involved in making cell wall materials have a slightly different shape and can no longer be bound by certain drugs.
6. Rhizobia are bacteria that colonize the roots of certain plants (legumes, including beans and peas). The host plant benefits from the prokaryotes’ ability to “fix” nitrogen, converting N2 from the atmosphere into a form that is usable by the plant.
7. Many species of bacteria contain the enzyme cellulase. More than 10 billion such bacteria and other symbiotic microbes may be found in a single milliliter of material from inside the digestive system of ruminant mammals.
8. Fungi, including those that cause athlete’s foot, use ergosterol to maintain healthy membranes. Animal cells do not make ergosterol, they use a similar lipid – cholesterol.
9. During retrovirus infection, a DNA copy is made of the virus’s RNA genome. A cut is made in the host cell’s DNA and the DNA copy of the viral genome is pasted into the host chromosome by a viral enzyme called integrase.
10. Prokaryotic cells contain smaller ribosomes (“70S” ribosomes) than eukaryotic cells (“80S” ribosomes). Both types of ribosomes synthesize proteins, but the macromolecules they use to do it are somewhat different.



2
Applications
_______ Oseltamivir, also called Tamiflu, binds and inhibits the viral protein neuraminidase.
_______ Clotrimazole is a drug that is used to treat certain infections. It interferes with synthesis of ergosterol, a lipid involved in phospholipid membranes.
_______ Penicillin is a drug that interferes with synthesis of peptidoglycans (these are biological molecules that are part protein and part carbohydrate) that are present in certain cell walls.
_______ HIV is often treated with several drugs that inhibit different parts of the viral replicative cycle. Raltegravir is an example of a drug that interferes with the integration of viral genes into the host cell’s chromosome.
_______ Cows, like other vertebrates, lack the ability to breakdown cellulose. Yet they are able to live on a diet of grass and other vegetation high in cellulose.
_______ Enzymes isolated from extremophiles have been very useful in laboratory research. For example, Taq polymerase facilitates PCR, a revolutionary technique for production of DNAs of particular sequences, which requires cycling reactions through high temperatures.
_______ Plants and animals require nitrogen to make biological macromolecules, however they’re unable to convert atmospheric nitrogen (N2) into a biologically useful form.
_______ Azithromycin is a drug that binds to 70S ribosomes and blocks synthesis of any new proteins.
_______ Methicillin-Resistant Staphylococcus aureus (MRSA) can cause life-threatening infections of the skin and bloodstream. One of the reasons MRSA infections are so serious is that they are resistant to treatment by many antibiotics, including methicillin and penicillin.
_______ The enzyme reverse transcriptase, isolated from retroviruses, is an important tool in molecular biology research. Scientists interested in learning what genes are turned on in particular cells use it to make DNA copies of RNAs they are studying (The DNA copies are useful because they are more stable).


When you have completed the matching activity, answer these follow-up questions:
• What types of infections can be treated with the following drugs?
o Penicillin
o Clotrimazole
o Azithromycin
o Tamiflu
o Raltegravir
• Why are these drugs (above) safe for you to take? That is, why don’t they kill your cells?
• Cancer cells are your own human cells that have become deregulated so that they divide and pile up in an uncontrolled way. Many chemotherapy drugs treat cancer by interfering with cell division and other cell processes.
o Why are there so many more side effects for individuals undergoing chemotherapy than for individuals taking antibiotics?

True or False????? HELP

1. In the field of epidemiology, increased prevalence of a disease in a population is the universal signal that disease control and treatment are not effective.

2. Cytoplasmic membranes of prokaryotes typically contain more proteins than cytoplasmic membranes of eukaryotes microorganisms.
3. Sanger (or dideoxy) DNA sequencing produces relatively short DNA sequence data, but is by far the least expensive DNA sequencing method currently available.
4. The (italicizes) abbreviation lac Z refers explicitly to the beta galactosidase protein/ enzyme.
5. Archaeal pathogens have been linked to some of the most virulent infectious diseases. 6. A bacterial mutant that is unable to make an amino acid required for growth (relative to its wild-type strain is termed an auxotroph.
7. When counting plaques to enumerate phage particles (as in the BIOL2026 Laboratory), the plaque represents lacK, not presence, of bacterial growth.
8. Because of competition with plant roots for nutrients, microbial numbers in the rhizosphere are typically much lower than in surrounding bulk soil.
9. Chemolithoautotrophy is the strategy that facilitates the existence of biological communities deep beneath the earth’s surface and near hydrothermal vents.

10. In a primary treatment (1 °) system of a municipal sewage/ wastewater treatment plant, the main goal is to remove ammonium (NH4+) using specific bacterial enrichment cultures.
11. The small intestine in human is the main site of microbial breakdown of partially digested food.
12. Root nodules of legumes contain nitrogen fixing bacteria.
13. Anoxygenic photosynthesis involves using/ removing electrons from H2O.
14. Algae and Cyanobacteria utilize generally the same two-photosystem biochemical mechanisms in the light- reaction of photosynthesis.
15. In bacteria, the only known reason proton motive force is generated is to power ATP synthase in cellular respiration/ oxidative phosphorylation.
16. Anaerobic respiration is only carried out by prokaryotes, however fermentation can be carried out by both prokaryote and eukaryal microorganism.

17. The general structure and biochemical “motors” of flagella are similar between Bacteria and eukaryotic cells, but fundamentally different in the Archaea.
18. Antibiotic resistance genes appeared in microbes (for the first time ever) only after human .. producing and releasing massive amounts of antibiotics to the environment.
19. Experiment by Esther Lederberg, and then later by Luria and Delbruck (that won them a Nobel prize), illustrated that genetic mutations in bacteria arose in the absence of selective pressures, rather than in response to selection.
20. Quaternary sensing is a mechanism used by bacteria to sense other bacteria and regulate gene expression accordingly (e.g. In the case of expressing the liac operon or initiating EPS production in biofilms).