update: Winston has become infested with mould.
In class we completed an experiment in which you create two "worlds" with different levels of CO2, and then examine the effect which it has on the temperature of the "worlds" as time passes. Independent Variable: Time Dependent Variable: Temperature of the "world" in °C Controlled Variables: Concentration of hydrochloric acid, mass of calcium carbonate "chips", volume of distilled water, time left for the observation of the worlds T h e r e s u l t sThe results above show that even within a small period of time (45 minutes) a difference in the temperatures of the two worlds has appeared. The world with more CO2 has increased more in temperature in comparison to the control. This tiny experiment done on a small scale gives an indication as to what has happened to the world due to the extreme increase in CO2 levels. Although the increase is small, it is significant and supplies evidence that higher CO2 levels do result in temperature increase. E v a l u a t i o nFrom the experiment in class, many improvements could be made in order to make the experiment more reliable. For example, many variables were not controlled in the way of which they should be. The mass of the calcium carbonate was not weighed out but instead judged by the rough estimation in the beaker. Likewise when we measured the volume of water instead of precisely using a measuring cylinder we used a rough guess of what we thought "looked the same". The temperature of the water could have been controlled in order to guarantee a controlled and equal test (this can be the same with the hydrochloric acid). Likewise a better cover for the beakers could have been used rather than cling film as the cling film could have had a small tear in it or perhaps it didn't cover the top fully on one of the beakers. All of these inaccuracies should have been controlled which would have consequently made the results more reliable and valid.
Through somatic cell nuclear transfer and cloning animals treatment for regenerative diseases has been developed. New medicines have advanced and consequently resulted in a positive outcome in the understanding and treatment of diseases. Haemophilia is a bleeding disorder within the blood which does not allow for blood clots to form. Instead the haemophiliac experiences prolonged bleeding which can cause huge complications both internally and externally due to the fact that this prolonged bleeding can occur from something as little as a paper cut. There are two types of haemophilia, the mutation occurs on different genes resulting in different types A and B. Use of genetic modification in human medicineThe role of nuclear transfer in stem cell therapiesWhat is somatic cell nuclear transfer?Somatic cell nuclear transfer is a laboratory technique used for creating an ovum with a donor nucleus. It can be used in many different areas of research and for different types of medicine. It is often used in embryonic stem cell research and in regenerative medicine, where it is referred to as therapeutic cloning. Somatic cell nuclear transfer can also be used in the first step of reproductive cloning. In somatic cell nuclear transfer the nucleus which contains all of the organisms DNA is removed and the remainder of the cell is discarded. At the same time the nucleus of an egg cell is removed. The nucleus of the somatic cell is then inserted into the enucleated egg cell, so the egg cell now has the nucleus of the somatic cell. After this insertion, the the somatic cell nucleus is reprogrammed by the host cell. This cell is then given a shock which begins the process of division. After many mitotic cell divisions whilst the cell cultured, the single cell forms a blastocyst which is the early stage of an embryo containing roughly 100 cells with almost identical cells to the original organism. examples of somatic cell nuclear transferDolly the sheep is perhaps the most famous cloned animal of all time. She was cloned at the Roslin Institute in Scotland on the 5th of July 1996. Animal cloning from adult cells is far more difficult than from an embryonic cell. Which is why when Dolly was produced, the only lamb from 277 attempts it was a major step in science for the whole world. Scientists used an udder cell from a six year old Finn Dorset white sheep. The scientists had to find a way to reprogram the udder cells which was needed to keep them alive but to stop them from growing anymore, they did this by altering the growth medium (which is like the 'soup') in which the cells were kept. Then the scientists injected the cell into an unfertilised egg cell which was enucleated and made the cells fuse through electrical pulses. The egg cell was from a Scottish blackface ewe. When the cells from the white sheep and blackface ewe the team needed to make sure that the cells would develop into an embryo. The cell was cultured for 6/7 days to see whether it would divide and develop the way that a normal cell would before it was implanted into a surrogate mother which was another Scottish blackface ewe. Dolly was born 148 days later. Once Dolly was born she lived a very pampered life at the Roslin Institute in Scotland. Dolly mated and reproduced normal offspring proving that clones are able to reproduce. Although Dolly seemed like a normal sheep she aged much quicker due to the fact that the DNA in the nucleus wraps up in chromosomes and shortens with each replication and her DNA was not from an embryo but an older sheep. Nor was Dolly entirely identical to her genetic mother as the mitochondria which are kept out of the nucleus were inherited from the egg donor. Dolly suffered from terrible arthritis in a hind leg joint and also from sheep pulmonary adenomatosis, a virus induced lung tumour which is common amongst sheep raised indoors. Dolly was euthanised on the 14th February 2003 at the age of 6, sheep can live up to roughly 11/12 years of age. pros of cloningDolly was created at the Roslin Institute as part of research into producing medicine in the milk of farm animals. Researchers and scientists have been able to successfully transfer human genes which produce useful proteins into sheep and cows. An example of this would be the blood clotting agent factor IX to treat haemophilia or alpha -1- antitrypsin to treat cystic fibrosis, which is an inherited condition when the lungs and digestive system can be clogged with a thick, sticky mucus. Inserting these genes into animals is a difficult and laborious process; cloning allows researchers to only do this once and clone the resulting transgenic to build up a breeding stock. This research of cloning technology has led to new ways and developments in producing medicines and is thus furthering our understanding of development and genetics. cons of cloning and the ethical issuesAnimal cloning and cloning itself brings about many arguments and controversies. One main argument against cloning is into the argument of humans playing God. Just how far should humans be able to interfere with bringing about new life and altering organisms. Altering life forms is argued by many that humans are surpassing the laws of naturing thus consequently leading humans into works that become 'unnatural'.
Not only can it be argued that this is unnatural but it also brings back the fear of the unknown. Many people argue that playing with genetics is dangerous and a step into the unknown. If people can now clone animals what else will people soon start to clone? What will be the next step? Another large argument against cloning is the fact that the majority of cloning attempts end in failure, you do not know how the clone will deal with life or what sort of issues may arise when the clone develops further. A genetic argument against cloning is that a larger gene pool is good and cloning does not enlarge the gene pool. Genetic variation is good within the human race so if cloning were to advance into human cloning this would be bad. PCR is the polymerase chain reaction, this technique is used for the purpose of amplifying DNA, to create many copies of the DNA sequence. Only a very small amount of DNA is actually required for the process to begin. The process starts by a small amount of the DNA going into the PCR machine in which a series of steps doubles the quantity of the desired DNA. The double stranded DNA is separated into two single strands at one stage of the cycle and then these single strands combining to create one double stranded DNA. The double stranded DNA is held together through hydrogen bonds. For the double stranded DNA to become two single strands of DNA these bonds must be broken. The DNA is heated to a high temperature consequently causing the hydrogen bonds to eventually break down and the strands separate. When the temperature drops, the hydrogen bonds are able to form again bringing the two strands together this is known as re-annealing. The machine separates the two strands by heating the DNA to 95° heat for fifteen minutes and then is left to cool for a short period of time until the temperature reaches 54° hea. This would allow the parent strands to reform a single strand of double stranded DNA however this is unable to happen as primers are present. Primers are short sections of the single stranded DNA. These primers bind to target sequences of the DNA and thus prevent the re-annealing of the parent strands. The primers start the copying of the single parent strands. The next stage is the synthesis of the double stranded DNA, using the single strands with primers as templates. Taq DNA polymerase is used to do this. Taq DNA polymerase is the perfect enzyme for this process as the enzyme originates from a bacterium, Thermus aquaticus, which lived in very hot springs. The temperature of the springs ranged from 50°C to 80°C. Most enzymes would denature at such a high temperature however Taq polymerase has adapted to be able to withstand and work at a very high temperature in order to avoid denaturation. Taq polymerase is used as it is able to withstand the temperature of 95°C without denaturing. It would work at the lower temperature of 54°C however its optimum temperature is 72°C, which is why the mixture is heated to this temperature whilst Taq polymerase is working in order to quicken the reaction. When at the optimum temperature of 72°C Taq polymerase adds roughly 1,000 nucleotides per minute! The cycle is started by heating to 95°C, this is done when enough time has passed for the replications of the selected base sequence to be completed. A full cycle of PCR can be completed in less than two minutes. Thirty cycles, which amplify the DNA by a factor of a billion takes less than 1 hour. With the help of Taq polymerase, PCR enables the production of huge numbers of copies of a selected base sequence in a very short period of time. |
Professor Laura M TotterdellPhD in physiology and cake making as well as quantum physics. Archives
April 2016
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