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An investigation to find out about the features of mitosis in the root tip of garlic (allium)

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Introduction

An investigation to find out about the features of mitosis in the root tip of garlic (allium) Introduction I have performed an experiment aiming to find out whether or not there are any defining characteristics in the mitosis cycle of a garlic root tip (or area of cell division). Mitosis is an essential part of any organism with eukaryotic cells life because it is how the organism grows and repairs itself. Mitosis is not required in some prokaryotic organisms such as bacteria because they divide by a process called binary fission where the D.N.A is attached to the cell membrane and duplicates itself and is pulled apart when the new cell splits from the old one. The process is very complicated because it requires the cell to split the duplicated D.N.A (which forms pairs of chromatids connected by the centomere called chromosomes) into exact pairs or one cell will have more of a gene than it is supposed to and can this can lead to problems. There are four stages or phases in the process of mitosis, they are named and what can be seen is described below * Prophase - The D.N.A coils up to become chromosomes, the nuclear envelope disappears and centrioles duplicate themselves. * Metaphase - The chromosomes line up across the equator (centre) of the cell and the centrioles move to opposite poles of the cell * Anaphase - The centrioles release microtubules (spindle fibres) and then they attach to the centomere of each chromosome and pull them apart into the chromatids. ...read more.

Middle

A null hypothesis Null hypothesis I believe that the amount of cells seen in each stage of mitosis will be evenly distributed between the four stages of mitosis (around 125 each), therefore meaning that each stage of mitosis takes an equal amount of time. To work out the chi squared we need to use this formula: x2 = (O - E)2 E E = expected data O = observed data I am going to use my average results to calculate my chi squared value. To work out the shi squared I will use a table like this: Stage of mitosis Expected (E) Observed (O) O - E (O - E)2 (O - E) 2 E Prophase 12.500 22.600 10.100 102.010 8.161 Metaphase 12.500 10.500 -2.000 4.000 0.320 Anaphase 12.500 8.900 -3.600 12.960 1.037 Telophase 12.500 8.000 -4.500 20.250 1.620 X2 11.138 This means that my chi squared value is 11.138 We then have to put the result into an x2 table; we have the DF so we can calculate the probability that the difference between the expected and the observed is due to chance or some other factor. Table 2 (below) is the chi squared table for DF 1 to 4. Table 2: A chi squared chart for the first 4 degrees of freedom DF 0.25 0.2 0.15 0.1 0.05 0.025 0.02 0.01 0.005 0.0025 0.001 0.0005 1 1.32 1.64 2.07 2.71 3.84 5.02 5.41 6.63 7.88 9.14 10.83 12.12 2 2.77 3.22 3.79 4.61 5.99 7.38 7.82 9.21 10.6 11.98 13.82 15.2 3 4.11 4.64 5.32 6.25 7.81 9.35 9.84 11.34 ...read more.

Conclusion

39 34 19 14 31 23 20 226 22.6 Metaphase 12 12 10 7 8 14 12 7 12 11 105 10.5 Anaphase 11 14 12 3 2 11 13 7 6 10 89 8.9 Telophase 13 11 9 1 6 6 11 5 9 9 80 8 The anomalous results are ones which I believe are unusually high or unusually low. These may be due to many of the factors I explained in my analysis of the results earlier in the investigation. I believe that the anomalous prophase results are due to the exclusion of the interphase stage and the anomalous results in the metaphase anaphase and telophase are due to the anomalous prophase results and in other cases due to mix ups between each of the mitosis stages. In my table the entire rows 3, 4 and 8 are highlighted this means that these people may have counted the cells incorrectly or had a lot more cells that appeared to be prophase but were actually in interphase. Conclusion In conclusion, I believe that although my results are not accurate enough to reach a correct assumption about the differences (or similarities) between the times taken for a garlic root tip cell to complete each stage of the mitosis. This is due to the likely fact that many of the cells recorded to be in the prophase stage were in the interphase stage, which led to the large differences between the results for each mitosis stage. ?? ?? ?? ?? Robert Henderson 12D2 - 1 - Robert Henderson 12D2 - 1 - ...read more.

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