Method:
Aseptic techniques to follow:
My results table: From this table I have decided to discard a number of the results because they are anomalies. The anomalous results are due to human error combined with misuse of the colorimeter. Prior to the experiment my group didn’t know that the colorimeter gave out two different readings; one of absorbance of light and the other transmission of light. This meant that when I recorded our results, it was hard to spot a trend due to a clear difference between those which were transmission (i.e. negative) and those of absorbance (between 0 and 1). Therefore, to overcome this problem, I inverted those negative values and plotted them on the graph. On top of this, other anomalies were generated which I believe could be easily improved upon. Firstly, I would take more care in ensuring the liquid broth was agitated and cloudy before taking a sample from it. This could be done by swirling the broth to allow the yeast cells to be more evenly distributed in the liquid. After removing the significant anomalies, I generated a new table and then plotted a graph of absorbance of light against time in hours. This graph demonstrates a general trend of upward growth. To begin with the growth is more rapid but as the time increases the gradient of the curve becomes less steep.
Evaluating the results there is a trend in the growth of the yeast, despite a number of anomalies, there is still general upward growth. To begin with the yeast cells are adapting to their environment in the growth medium and have not yet reached their maximum rate of reproduction. This is not shown on the graph due to the fact that the earliest recording we took was after 18 hours of incubation. I believe that if we took earlier readings and replotted the graph, the gradient would have resembled the typical lag phase of growth. This would be a key area for improvement. However, because this was not the case, the graph I created began with the exponential growth phase. As the curve continues at a steep gradient, the exponential phase of growth is very clear to see. This phase is where yeast reproduction is at its highest due to availability of nutrients and an optimum temperature. The gradient eventually becomes less steep demonstrating the stationary phase where the number of yeast cells produced is not increasing. This is shown on the graph as the gradient begins to level off. This may be due to competition over space or nutrients as it reaches its carrying capacity.
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Aseptic technique is to carry out laboratory procedures with sterile equipment and to prevent microbial contamination. Equipment:
The aim of this experiment was to move a sample of the monoculture from the test tube into the nutrient agar medium whilst avoiding contamination from foreign microorganisms. Many techniques were carried out to prevent contamination from occurring. The method:
This method requires the aseptic techniques to be carried out carefully. Another aseptic technique would be that during the experiment it is best not to place the equipment down as that could cause further contamination and the longer the instruments are exposed to the air the more bacteria are likely to build up and cause microbial contamination. We recently looked into the basics of synthetic biology and I learnt about how living organisms can be so easily manipulated in the lab by interfering with the natural processes such as protein synthesis. I found it interesting what synthetic biologists have predicted will be possible in the near future such as creating bullet-proof flies. The possibilities are endless and it's weird to think how synthetic biology is the gateway to creating new species with abilities that were previously thought to be beyond our reach. The advancement in technology and equipment has enabled progress in synthetics. Through understanding the way in which transcription and translation works, scientists have the ability to manipulate parts of the genetic code and assemble it in any way. This creates new sequences which will lead to coding for different proteins, therefore it will be able to carry out different functions.
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Ciara Branagan
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October 2016
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