Viable Cell Counting In Yeast Suspension Biology Essay

Viable Cell Counting In Yeast Suspension Biology Essay The aim of this experiment was to estimate the number of viable cells in a yeast suspension that was already provided. Estimations of the viable yeast cells were taken via two methods of plating; pour plating and spread plating, of which hot agar was used with the pour plate technique. The results that were obtained for this experiment show that overall; the spread plate method gives a higher yield of viable yeast cells compared to the total count value of 2.8 x 10^7. This experiment was conducted to estimate the number of viable cells in a yeast suspension, already provided. The definition of a viable cell, as stated in the Collins English Dictionary, 2008, p991 is capable of growth. Therefore, the definition of a viable yeast cell is a yeast cell capable of living and being able to grow. In industrial and research settings, there is a need to quantify the microbe content of microbial products. The method for doing this varies for different types of microbes. Traditionally, the first microbes to be used commercially were bacteria and yeasts. These are typically single-celled species that can be grown in natural and artificial media, and are well-suited to growth in agar gels on Petri plates. Using this method, individual cells or clumps of cells will form discrete colonies, which become visible to the naked eye as the colony grows. Counting the number of colonies provides a direct way to track the original number of discrete microbial units. A count determined this way been dubbed the number of Colony-Forming Units or CFU for short. CFUs are only applicable to single-celled microbes that can be grown on nutrient media, such as bacteria, yeasts, or spore-forming moulds. As the total count for the number of yeast cells was so vast (2.8 x 10^7) dilutions were made in order for a characteristic estimate of the total count of yeast cells to be made. Having diluted the sample enabled the human eye to count an estimate of the yeast cells. If dilutions had not been carried out, the sample of yeast cells would have been far too large and it would have been extremely time consuming and impossible to count the number of yeast cells. A haemocytometer enables for an estimate of the total number of yeast cells present. It has a known volume of chamber and area which is etched on the glass. A cell suspension is able to be above the known area. The chamber is then filled with a yeast suspension then covered with a cover slip. An average number of microbes can then be counted in the ruled area to give the number of yeast cells per cm ³. The aim of this experiment was essentially, to estimate the total number of yeast cells in a culture and to estimate the number of living (viable) yeast cells. Materials and Methods The total count of the yeast cells originally estimated by the haemocytometer was 3.8 x 10^7, however, it was later concluded that this was incorrect due to a mix up from another class. The new result for the estimated total count of the yeast cells was 2.8 x 10^7. This number was clearly too large and a series of ten fold dilutions were carried out in order to make it easier to estimate and investigate the viable yeast cells. A series of ten fold dilutions were needed as this is an important technique in identifying the viable cells. As a figure of 2.8 x 10^7 was established and it is vital that the number of colonies attained remains within the range of 30-300. So the dilution for a range of 30 300 is 1/100 (10^-2), however, it is essential that further dilutions, both above and below 1/100 are used; 1/10 (10^-1) and 1/1000 (10^-3). To make the estimation more accurate, dilutions of 10^-4, 10^-5 and 10^-6 were also used for both pour and spread plates. For full method, please refer to introduction to biology, microbiology and pharmacology practical booklet, pp 13-14. Results The results obtained for the pour plate and spread plate methods were as follow: 10^-1 10^-2 10^-3 10^-4 10^-5 10^-6 Pour plate (ml) TNTC TNTC TNTC TNTC 83 8 Spread plate (ml) TNTC TNTC TNTC 100 10 1 Key: TNTC Too numerous to count To determine the number of colony forming units (CFU) cm^-3 this calculation was used: Counts on plate x (1/dilution) x (1/volume inoculated (ml)) The calculations that were carried in order to determine the number of colony forming units (CFU) cm^-3 of the original culture for the pour plate and spread plate are shown below: Calculations for pour plate method: 83 x 1/10^-5 a 1/1 = 8.3 x 10^6 CFU, ml Calculations for spread plate method: 100 x 1/10^-4 x 1/0.1 = 1.0 x 10^7 CFU, ml The volumes inoculated for the pour and spread plate were different, the pour plate was inoculated with 1.0cm^-3 and the spread plate with 0.1micrometer. Discussion The table in the results sections shows that the values of the colonies that were counted for each of the plating techniques show good continuation, especially with the spread plate as the figures are increasing by a factor of ten each time. The figure obtained for the total count was 2.8 x 10^7, comparing this to the figure calculated for the pour plate method, 8.3 x 10^6 CFU, ml there has been a loss in the number of viable cells using this method, there has been a decrease of 1.97 x 10^7 of viable yeast cells. Comparing the total count value to the spread plate figure of 1.0 x 10^7 there was also a loss of viable yeast cells, with a loss of 1.8 x 10^7. This decrease in viable yeast cells compared to the pour plate loss is lower. The hot agar used in the pour plate technique may injure or kill sensitive cells; thus spread plates sometimes give higher counts than pour plates.(p 130, Microbiology, Seventh Edition, Joanne M. Willey et al) The above statement backs up the results of the experiment, as the spread plate technique has given a considerable higher count of viable yeast cells. Other factors that may have resulted in the smaller number of viable yeast cells in the pour plate method could have been that there is a much higher likelihood that clumps of the colonies may have formed together in portions of the plate, making it much more difficult to count. This occurs less in spread plating, as the clumps are broken up, and therefore there is a better distribution of the cells. Other factors that may have affected the results obtained for this experiment were the techniques used for the serial dilutions. With each sequential serial dilution step, there may have been transfer inaccuracies that lead to less accurate and less precise dispensing. This meant that the highest dilutions had the highest number of inaccuracies. Also, after every inoculation, the dilution must be thoroughly mixed; this was not carried during any of the dilutions, so this may have also affected the number of viable yeast cells. Finally, when doing viable counts, the higher dilution is, the more error is found in estimating the count of the original volume. For example, there were 10 colonies growing on the 10^-5 spread plate, and it was estimated that there were approximately 500000 colonies in the original suspension, but this was only an estimation to the closest hundred thousand. Likewise, with higher dilutions, such as the 10^6 on the pour plate, it was only estimated to the closest million. There were some limitations to the experiment, which may have altered the results slightly. Not having much experience in using the Gilson pipettes may have had an impact on the accuracy of the pipetting that was done during the serial dilutions.

Visiting Mountain City :: Descriptive Essay About A Place

Visiting Mountain City Mountain City, Tennessee, is my hometown. I have lived in this small town located in East Tennessee all my life. It has many attractions, shopping places, and great places to eat. Most people don’t realize what the town has to offer--everything from shopping in the downtown area to relaxing in one of the numerous parks. There are also several creeks and camping facilities for the outdoor man. This makes Mountain City a great place to go and forget about all your troubles. Mountain City was established in 1885; the town was first called Talyorsville. The town has grown tremendously since its establishment. Located about 45 miles from Johnson City, it’s a perfect place to visit for a day. The drive is only about an hour from E.T.S.U. Mountain City is also located about 30 miles from Boone, North Carolina, where skiing’s a major attraction. Since I have lived in Mountain City all my life, in my opinion, the fall season is the best time to go. The trees all around are full of color. This time of year is a perfect time to hike on one of the various trails, which will lead you deep into the Appalachian Mountains. Some of the trails lead to spectacular views of the town. The Deer Run Trail is a wonderful trail to hike in order to view the small town. The trail is about a mile long and very challenging. During the fall season, the weather seems warm during the day and cool throughout the night. I’d suggest taking some short sleeve shirts for the day and some long sleeved shirts for the chilly nights. If the outdoors does not interest you, then Mountain City offers several stores to shop at. Downtown Mountain City is packed full of little stores filled with all kinds of treasures. There’s a variety of stores and wide selection of items to choose from. Some stores located in the downtown area are the City Shoe Store, Cornet Furniture, Auto Zone, Downtown Antiques, Hidden Treasures Antiques, and for the young people, Corner Pocket Arcade. The downtown area is not the only place to shop. I learned from my visit that there is a Dollar Store, Family Dollar, Tumbleweed Western Wear, Family Book and Card, and a Stanley Knitting Mill Outlet store. Some of my favorite places to shop are the little booths set up along side of the road, that feature crafts and different selections of souvenirs.

Bottled Water Essay

Bottled water is one of the easiest ways for getting â€Å"good† water. Bottled water is every where in offices, airplanes, stores, homes and restaurants across the country. People think that bottled water is the best option for their health instead of drinking tap water because they say tap water is not completely pure. What they don’t know is that tap water is the same as drinking bottled water because industries like Nestle gives us tap water in plastic bottles. Plastic bottles contain many chemicals that damage our system by giving us different diseases. This increases the risk of people getting diseases while years pass. People don’t research enough about how is bottled water is made and how they are just taking away our money in this type of products. Before watching the video about bottled water, I realized how bottled water affects our system like a person and how it affects our environment. After watching the video I really didn’t drank bottled water because I am an ecologic person. I have always recycled bottles and in my old school I promoted ways to recycle bottles, and why to recycle. I realized all the pollution is going on in the earth and I like to keep it clean. Even if I am the only person who is recycling one person makes some how some difference for the planet to breath at least a little bit. It makes me sad how people don’t care about our planet knowing all the struggles and the lack of resources we now have. I have my personal plastic bottled to refill to drink water. This is some how good for the planet because we can use one water bottled and drink tap water and recycle. If industries like Nestle are giving us tap water in their fancy plastic bottles to make us believe that they are giving us pure water, why not drink tap water if it is the same. In reality, bottled water is just water. Bottle water means garbage, plastic bottles just makes more garbage in the planet and not all of them are recycled as the recycled industries say they are. Most of them end in the Pacific Ocean, rivers, lakes, etc. Plastic bottles besides killing us with their chemicals they also kill animals. This plastic bottles end up in lakes and in natural environments. Fish, birds, and other animals end up eating some how plastic because it is in their environment, this increases the percentage of animals dying in our natural environment; causing endangered animals. It makes me sad how people knowing how plastic bottles or even in my Earth Science class know how tap water is the same as bottled water are the same and they keep buying them. Why not buy your own plastic water and drink tap water if it is going to be the same kind of product and this way we can recycle by using the same water bottle many times, and drinking the same product that industries like Nestle are providing us in bottled water. I hope that with this critical analysis some of my classmates realize how bottled water is bad for their health and how bottled water damage not only us but also our environment. There are many things going on besides bottled water polluting our environment and damage other living animals. Lets no be selfish and take in consideration all of this information. http://www.epa.gov/ogwdw/faq/pdfs/fs_healthseries_bottlewater.pdf http://www.rd.com/health/rethink-what-you-drink/ http://www.chem.duke.edu/~jds/cruise_chem/water/wattap.html http://topdocumentaryfilms.com/tapped/

The Ethical Theories Of Duty Ethics And Virtue Ethics Essay

â€Å"I would rather be a good man than a great king† said the character Thor in Thor: The Dark World. In these words we find a frightening tension. Almost everyone agrees that it is good to be ethical; this is an easy affirmation. It is much more difficult, though, when ethics is in direct opposition to success. This dichotomy- between ethics and success- will no doubt confront an engineer during a professional career of any substantial length. Can you say that you would rather be a good man than rich? Or popular? Or a successful engineer? What should happen when an engineer faces this question? One real world example that can shed some light on this problem is what is known as bid shopping. This essay will provide a thorough definition of the problem of bid shopping and the ethical dilemma surrounding it. It will then apply the ethical theories of Duty Ethics and Virtue Ethics to the question. And seek to show that bid shopping is unethical according to both ethical theories . 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