BIOT 505 Lecture Notes - Lecture 8: Nitrogen Fixation, Root Nodule, Genistein

80 views4 pages

limewildebeest336

2 Jan 2018

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Exploitation for imprroved crop gowth donald l. smith. After carbon, o2 and hydrogen, it is the most abundant element in living systems. C, g, and o come as gases and are easily replenished. N is the element most likely to limiting on field scale. It comes from the earth and microbes in the soil put it into the air. If no chemical equilibrium with the surface, then there is probably life on planet. If there is, then most likely no life! So can tell if there is life on other planets from the earth. Nitrogen fixation: 80% of the atmosphere is n2, but plants cannot access this. Some prokaryotes have nitrogenase, which allows them to take the n from the air. Legumes, like soybean, enter into a symbiosis with soil bacteria (rhizobia). Evolution in the absence of n limitation has made legumes high in protein. (most proteins are made from rubisco)

Related Questions

1. Deep sea thermal vents are characterized by extremepressures, very high water temp (exceeding 100 celsius) and veryhigh concentrations of minerals. What type of prokaryotic organismsare most likely to be found there and why?

Archaea; tetraethers are morethermally stable.

Archaea; the partial membranessurrounding the DNA provide more protection.

Bacteria; the peptidoglycans in thecell walls keep them from overheating.

Bacteria; they use the energy from the minerals to power theirchloroplasts.

2. Farmers often practice crop rotation to help enrichagricultural fields. Why are beans and other legumes often used inthe rotations?

Legumes remove toxins from thesoil.

Less carbon dioxide.

Bacteria in legume root nodules arenitrifiers.

Legumes enrich the soil by formingheterocysts.

Beans fix nitrogen.

3. The fungus Penicillium produces a compound thatblocks peptidoglycan assembly. Why is a fungus trying to killbacteria?

The compound produced by the fungusis used for nitrogen fixation, the antibacterial properties areaccidental.

The fungal compound is produced inresponse to a bacterial invasion of the fungal hyphae.

Fungi and bacteria are bothdecomposers and compete for resources.

Fungi eat bacteria.

4. If Chlamydia is often asymptomatic, why is it necessary totreat it?

Pelvic inflammatory disease is apotential complication and can render women sterile.

Tertiary chlamydia causesneurological problems.

Chlamydia infection is a major riskfactor for cervical cancer.

Vertical transmission of chlamydia causes birth defects.

5. A mutant strain and the wild-type have different growthrequirements, they are given below.

Wild-type growth factors: A,B,C,D
Mutant growth factors: A,B,C,D,E

Select all the true statements concerning this situation.

It is possible to formulate a mediathat will allow the mutant to grow but not the wild-type.

A minimal medium will allow themutant to grow.

The mutant is auxotrophic.

Replica plating would be used toidentify the mutant.

An early stop codon may have occurred in the mutant.

6. Cell X has 45% adenine in it's genome and a thickpeptidoglycan cell wall. It is most likely a(n)

cyanobacteria

fungal endospore

low CG Bacteria

thermophilic archaean

actinobacteria

7. Are transformation and transduction the same process?

No; only transformation passes ongenes for pathogenicity.

Yes; they both involve theacquisition of viral genes.

Yes; both processes transferspecific gene products to a specific bacterium.

No; although both involve gene transfer the sources of thegenetic material differ.

8. In terrestrial environments, nitrogen fixation only occurs insoils. Why is this the case?

	Free oxygen acts and atranscription inhibitor of nif genes.
	The enzymatic activity of thenitrogenase complex is inhibited by oxygen.
	UV-radiation denatures thenitogenase enzyme complex.
	nif genes are sensitive tolight.

raspberrylouse321

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 ~80Â°C (175Â°F). It has adapted so that its enzymes are most functional at the elevated temperatures, compared with many organismsâ enzymes that function best ~37Â°C (98Â°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 âCentral Dogmaâ 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 prokaryotesâ ability to âfixâ 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 athleteâs foot, use ergosterol to maintain healthy membranes. Animal cells do not make ergosterol, they use a similar lipid â cholesterol.
9. During retrovirus infection, a DNA copy is made of the virusâs RNA genome. A cut is made in the host cellâs 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 (â70Sâ ribosomes) than eukaryotic cells (â80Sâ 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 cellâs 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 theyâre 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:
â¢ What types of infections can be treated with the following drugs?
o Penicillin
o Clotrimazole
o Azithromycin
o Tamiflu
o Raltegravir
â¢ Why are these drugs (above) safe for you to take? That is, why donât they kill your cells?
â¢ 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?