Example Answers to Aseptic Technique and Streak Isolation Questions PDF

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lab micro 234 example homework questions and answers...

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Aseptic Technique Questions 1.

What is the purpose of aseptic technique? Aseptic technique is used to decrease the probability of contaminating plates, tubes, and cultures with unwanted microorganisms.

2.

Describe the procedures that are part of aseptic technique. The procedures used in aseptic technique all serve to minimize the chance of contamination. These procedures include: Handwashing – this reduces the microbes found on hands Disinfecting the benchtop – this reduces the microbes found on the work surface Keeping plates closed when not in use – if a plate is closed, microbes in the environment cannot fall onto/into the medium Work with plates with lid side down – this is a reminder to close the plate, and prevents the medium from prolonged exposure with the environment Don’t place caps or loops on bench – this prevents contamination of the bench surface and prevents contamination of sterile loops and caps Sterilization of loops and needles – sterilize the loop/needle before beginning and exercise, and whenever it is required

3.

What should be done with tube caps when using proper aseptic technique? Caps should be held in the hand; caps should not be placed on the bench

4.

How much time is required to properly sterilize inoculating loops and needles? Inoculating loops and inoculating needs should be incinerated for at least five seconds to achieve sterility

5.

Where should inoculating loops and needles be stored during use? Loops and needles can be stored by placing the handle in the incinerator base during use.

Streak Isolation Technique Questions 1.

What is the function of the streak isolation technique? The streak isolation technique is used to produce individual colonies of bacteria on the surface of solid medium. These individual colonies are used to create and maintain pure bacterial cultures.

2.

How does the streak isolation technique work? Each streak reduces the concentration of cells as the loop is dragged across the surface. As the density decreases, individual CFUs are separated from others.

3.

What is a CFU? CFU stands for colony forming unit. A colony forming unit is a cell or small group of viable cells that gives rise to a colony.

4.

What is a colony? A colony is a discrete population of bacteria (culture) on the surface of solid medium.

5.

What is a pure culture? A pure culture is a bacterial sample that contains only a single species of bacteria. (microorganism)

6.

How can you ensure that your loop is cool when streaking between quadrants? The incinerated loop is touched to a sterile area of the medium prior to performing a streak. Any residual heat in the loop is transferred to the medium, cooling the loop sufficiently so that it will not kill bacteria....