Cell Respiration Lab Ap Bio

A person who is going to hike an omelette prepared using egg farm. The tortilla is prepared the night before. Unfortunately, these eggs are contaminated in the shell with Salmonella enterica . By break to beat them there is an inoculation of these microorganisms in food. That person likes the tortilla curd is not everything, so that cooking does not end with the pathogenic bacteria found in the innermost part of the tortilla. When finished it, that person leaves the tortilla to cool to room temperature. At 9 am the next day, put the tortilla in a pan that you enter in your backpack and hiking.

Data: Number of

S. enterica in the shell: 1,000 cells per square millimeter. Eggs
used: 6 eggs
Inoculation: shows 25% of bacteria in 1 cm egg box for

Maximum cooking temperature reached inside the tortilla: 60 º C
actual cooking time inside the tortilla: 2 minutes
Decimal Reduction Time Salmonella under these conditions: 0.5 minutes

temperature overnight (12 hours time): 15 º C
specific growth rate at 15 ° C. μ = 0.23 h-1

average temperature during the trip: 28 º C

specific growth rate at 28 ° C. μ = 0.87 h-1

minimum inoculum should be taken to S. enteric infection occurs: 1 million bacteria.

Question: estimate the time that the intake of a spike of the tortilla will cause salmonellosis with 100% certainty.

Note for non-English speaking: 1 skewer tortilla is a quarter (approx.) of it

Dry Tongue During Sleep

hound

genetically engineered a group has constructed a mutant Escherichia coli in the biosensor system that triggers the movement of the flagellum.

If inoculated wild type, call-1 strain in semisolid agar the bacteria can "Swim" and spread around:

wild strain:

(*) click on image to view larger

In the mutant strain, called strain-2, has the deleted gene chez encoding the protein Chez. Without this protein the flagellum movement control is lost.

First question: How do you behave the mutant? Does semisolid agar diffusion will be higher or lower than in the wild strain?

A the research team then takes the strain lacking Chez and I introduced a plasmid containing the gene for this protein, but under the control of a ribointerruptor (riboswitch) . This new strain is called strain-3.

The ribointerruptor works as follows:

• In the absence of a molecule, let's call it molecule A, the gene messenger mRNA chez can not be translated by ribosomes.


• In the presence of the molecule A, the mRNA of the gene chez can be translated by ribosomes.

Researchers Strain-3 inoculated in a semisolid agar plate where it has added a drop containing the molecule A in one side of the plate.

Second question: How will behave Strain-3 at the plate? Do or get closer to the molecule A?


This research group also introduced the gene for Green Fluorescent Protein or GFP ( F G reen luorescent P rotein ) in the strain-3, thus the strain-4. This bacterium emits green fluorescence by the protein

Third question: What practical use could be strain-4?

(*) Figure produced from the book " Brock. Biology of microorganisms " Pearson Publishing

Famous American Chapstick

Biodeterioration of cultural heritage

A large number of caves containing prehistoric paintings ( Altamira Cave of the Bats, ...) have been closed to public visits to avoid damaging them. Despite the darkness and lack of nutrients from the environment, microorganisms can grow. The combination of carbon dioxide produced by the visitors and the microbes living on the surface of the rock lead to the degradation of paintings. In a first phase sought to avoid such degradation by using chemical biocides but these proved to be much more aggressive against the paintings against microorganisms. It was observed that the first stage of biodeterioration of a painting usually begins with the appearance of a blue-green stain. On this blue-green stain becomes available a biofilm composed of a variety of bacteria and fungi that will attack the paint.

Recently, the European Community has initiated a project that aims to prevent degradation and allow resumption of visits. There several research groups and each has developed a specific strategy to solve the problem. Here we describe the two most promising in terms of its preliminary findings and has failed:

• Strategy A: Lighting the caves with a blue-green light. It was observed that avoids the appearance of spots of the same color and therefore no subsequent biofilm develops.

• Strategy B: Use of synthetic siderophores. Siderophores are molecules for iron chelators. This strategy is used both in the initial stages of biofilm formation, as in the more advanced. It is observed reduced biofilm growth and even their disappearance.

• Strategy C: Use of specific antibiotics. The use of fungicides, bactericides or only attacked a certain group of microorganisms (antibiotics against Gram + or against Gram -) decreases the population of these microorganisms in the biofilm. However, the treatment does not appear to be effective or even initially, it is not observed any decrease in the growth of biofilm during treatment. To make matters worse, in the long term appear microorganisms resistant to these compounds, so that the treatment stops be fully realizable.

Questions:

1. What kind of organisms are affected by the strategy A?


2. Considering the answer to question 1, explain why they are the first organisms in the biofilm and how can these organisms live and reproduce in an environment like a dark cavern


3. Why is treatment with antibiotics ineffective even initially?


4. Why synthetic siderophores are effective in inhibiting the growth of the biofilm?


5. you show microorganisms resistant to siderophores?

Red Dot Scope Magnifier

biofertilization

A company that produces bio-fertilizers is testing the potential of two species of cyanobacteria as nitrogen fixers. One species in the genus Oscillatoria and other gender Anabaena. Below shows a graph comparing the efficiency of nitrogen fixation in both species over the day-night cycles.




explains why the behavior of both species is so different.