1. Wly would only \'most\' proteobacteria stain Gram-negative? Can you think of
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Question
1. Wly would only 'most' proteobacteria stain Gram-negative? Can you think of some that would either not stain or stain Gram-positive? Are these broad classifications useful?
2. Purple nonsulfur bacteria be photoheterotrophs or organoheterotrophs. what are the differences between those two?
a. What controls the appearance of purple nonsulfur bacteria?
b. Why would O2 inhibit the production of the pigments? What type of metabolism (photoheterotrophyo r organoheterotropy) happens under aerobic conditions? How do you know?
3. Agrobacterium tumefacians is commonly used to genetically transform plants in the laboratory. What type of horizontal gene transfer does this remind you of? Why?
4. Contrast the survival strategies of Gammaproteobacteria (E. coli), Deltaprotebacteria (M. xanthus), and Epsilonproteobacteria (H. pylori). How do they take advantage of their enviornments to grow?
5. Why do you think the vector-borne disease mostly localized to the Lyme Disease is still mostly localized to the northeastern US even now during frequent cross country travel? Use the transmission cycle in your answer.
6. One of the most commonly cited reasons viruses are not alive is that they cannot reproduce on their own. Given this, why are obligate intracellular pathogens like Rickettsia and Chlamydia considered alive?
7. Evaluate this statement: Cyanobacteria and myxobacteria can exhibit multicellularity.
Explanation / Answer
2. purple nonsulfur bacteria are photoheterotrphs.
photoheterotrophs - hetertrophic phototrophs - organisms that use light for energy but cannot use carbondioxide as their sole carbon source.
organotrophs : they obtain hydrogen or electrons from organic substances.Organotrophs exploit reduced carbon compounds as energy sources, like carbohydrates, fats, and proteins from plants and animals
a. They are pigmented with bacteriochlorophyll a or b, together with various carotenoids, which give them colours ranging between purple, red, brown, and orange.
b. purple bacteria do not produce oxygen, because the reducing agent (electron donor) involved in photosynthesis is not water.Purple non-sulfur bacteria do not release sulfur because instead of using hydrogen sulfide as its reducing agent, they use hydrogen. While these bacteria can tolerate small amounts of sulfur, they tolerate much less than purple or green sulfur bacteria, and too much hydrogen sulfide is toxic to them.
so, if there is oxygen, the pigments get lesser.
1. All "Proteobacteria" are Gram-negative, though some may stain Gram-positive or Gram-variable. The Firmicutes and Gram-negative Proteobacteria cell envelopes differ most notably by the presence or absence of an outer membrane.While many Firmicutes stain Gram-positive, some do not.
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