Microbio Exam 2

a eukaryote that grows at moderate temperatures, low water activity, and uses oxidation of chitin (organic molecule in insect shells) as an electron source would be considered

a mesophile, xerophilic, and an organotroph

synergistic symbiont

chlorobium, a photosynthetic, sultfur-oxidizing, green bacterium is able to survive in the ocean benthos because

green sulfer bacteria can absorb heat energy from hydrothermal vents to drive photosystems I

You find a colony of E. coli floating in your can of olives (2M NaCl). What mechanisms might E. coli use to withstand the high salt environment

Using sodium/potassium ion pumps to replace Na with K+

Marine dead zone, because heterotrophic bacteria initially catabolized the excess carbon from the wastewater runoff using aerobic respiration, consuming most of the O2 in the water column

No electron transport chain is used, so microbes compensate for low ATP production in the cell by fermentating large amounts of glycolysis products that can regenerate NAD+ for glycolysis

Which of the following factors most likely contributes to genome contraction (loss of genes)

Transition to an obligate human pathogen

Professor Jeff Marlow is doing another deep sea expedition this year where he will be collecting corals from turneff atoll. upon return, he reports that all of the corals had bleached (or lost their algal symbionts, Zooxanthellae) this year. This year was exceptionally warm, so you suspect that the corals likely bleached because:

high temperature damage the reaction center of the photosystem in Zooxanthellae

Chemical energy from redox of external molecules, electrons from H2S, carbon from carbonates (ex. CaCO3)

The thioautotrophic gammaproteobacteria can regulate many intracellular factors in order to survive near the hydrothermal vent at the bottom of the ocean. However, the bacteria cannot regulate

intracellular pressure

high concentrations of one subunit (AccB) of acetyl-coA carboxylase

Clostridium difficile can cause disease in the colon, but it can be treated with fecal transplant because:

c. difficile is outcompeted for nutrients by the highly diverse microbial community present

Neither mutant would glow

antibiotic resistance in tetracycline-resistant bacteria involves regulating the expression of genes that remove antibiotics

de-repressing transcription when tetracycline binds to a repressor as an inducer

which process always results in a net consumption of energy (ie, consume more ATP than it produces) in a bacterial cell?

calvin cycle

the top bacteria probably couple glucose oxidation (ie glysolysis) with o2 reduction, a reaction that has a very negative delta g value and so produces more free energy to use in bio synthesis than the anaerobic respiration conducted by the bottom bacteria

the sugar transport genes have multiple promoters, which are recognized by different sigma factors and begin transcription at different distances from the start codon of the genes

Secreting proteases that damage the host tissue, initiating an attack by the host immune system

Which group of organisms is most likely to fix CO2 via the reverse TCA cycle, rather than the Calvin cycle

green sulfur bacteria (ex chlorobium)

it produces carotenoid pigments that absorb UV light

For the plant-fungus-virus endophyte system discovered in extremely heat-tolerant tropical panic grass, what is the virus to the plant?

mutualistic symbiont