Wednesday, April 18, 2012

Bacterial ID Lab and Questions


Completing this virtual lab and answering the following questions helps meet Standard 3: Lab Skills.

First, go to:



In this virtual lab you will assume the role of a lab technician in a modern molecular biology laboratory.  As such, you are responsible for providing lab results to medical doctors for use in diagnosing their patients.  Be sure to follow the steps of the procedure in order and to make use of the notes on the right side of the computer screen.  As you work through the lab, answer the following questions:


1. As the medical technician in charge of this investigation, what are you trying to determine about the tissue sample provided to you?
I am trying to determine if I can grow bacterial colonies on a solid medium culture dish.

2. How did you prepare the DNA to be used in this investigation?
            You take a wire loop and extract the bacterial colony from the dish. Then you transfer the bacterial colony into the microcentrifuge tube. From here you add digestive enzymes to your sample. You add digestive buffer to the same tube. Once that is done you let the tube sit for several hours. Once the hours are done and your sample is ready you heat-inactivate the digestive enzymes. Now you will spin down cellular debris for removal from your sample.  You then transfer the superantant to the PCR tubes. Then your sample preparation is complete.

3. Describe how PCR is used to make copies of DNA sequences. Use the animation and notebook entries in the PCR Amplification step to guide your answer. Note that you may replay the animation as needed.
The PCR separates the strands of DNA, annealing the primer to the template, and the synthesis of new strands. This takes less than two minutes. Each step is carried out in the same vial. At the end of a cycle, each piece of DNA in the vial has been duplicated. The cycle can be repeated 30 or more times, and each newly synthesized DNA piece acts as a new template.

4. Summarize the technique used to purify the PCR product.
            First you set up the microconcentrator column. You add buffer solution the the column. Now add the PCR product of the column. Now place the tubes on ice. Then load the column into the cenrifuge. Now you need a new tube to invert the column. Now add buffer solution to the inverted column. Discard the first collection tube.Load the inverted column into the centrifuge. The column is no longer needed, so discard it. The PCR product had been purified.

5. What is produced during the sequencing prep PCR run? Use the animation and notebook as needed in thinking through your answer.
            Copies/ sequences of DNA will be produced.


6. Describe how the automatic sequencer determines the sequences of the PCR products.
            They stop the sequence at a certain point and then continue to the next section. They repeat this process thousands of times.


7. What does BLAST stand for?
            BLAST stands for Basic Local Alignment Search Tool.


8. What conclusions did you make using the results of the BLAST search?  Did these conclusions support a clinical diagnosis for the patient (what disease did they have)?
            It was very easy to find what was mutated in the DNA. Yes and they had Bartonella henselae.

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