What Duration of Ultraviolet Exposure Kills Bacteria - Lab Report Example

This has lead to modification of the law by replacing the speed of reaction constant by the growth rate constant. The modification proved not to be ideal since the graph s obtained after plotting the logarithm growth rate constant against reciprocal absolute temperature results into curves instead of a straight line. It is good to note that the same relationship is applicable to the breakdown of nucleotide and the growth of yeasts and mould (Pommerville, 2007). Ultra violet light is an electromagnetic radiation whose wavelength is less than that of visible light but more than that of X-rays and falls within the range of 10 nm to 400nm with energies of between3eV and 124Ev.

My study Hypothesis is that; any amount of UV light exposure will kill bacteria in culture media. Numerous for both. Numerous for both Numerous for both 30 and 23 137 and None Numerous for both Numerous for both Numerous for both 110 and 178 159 and 240 Line chart with the breakdown of the results obtained from the experiment. LINE GRAPH Figure; Showing number of counted bacteria against time. Discussion A change in the DNA base sequence can be referred to as mutation. This change can be beneficial or of neutrality to an organism but in most cases it does turn out to be harmful due to the fact that it results into loss of useful function of a cell.

Mutation in the case of bacteria is natural and does happen at a speed of 107-108/base pair in one round of replication. This speed increases in the presence of mutagens. These mutagens can be in the form of chemicals likes nicotine or also in the form of electromagnetic radiation. For the electromagnetic radiations considered as mutagen, they are broadly divided into two types; ionizing radiation and non-ionizing radiation. Ionizing ones carry a lot of energy that can remove electrons from molecules in a cell like DNA or RNA.

They include x-rays or gamma radiations. Ultra-violet (UV) radiations on the other hand form part of the non-ionizing radiation. Its mutagenic effect comes by it exciting the electrons in the DNA molecules leading to the formation of an extra bond between adjacent pyramidine bonds and for this reason, it is called pyrimidine dimer (Pommerville,2007)UV light is invisible to the naked yes and has high energy than the normal light. The light is absorbed by the double in pyrimidine base, opening the bond and allows it to react with the surrounding molecules.

In case the next molecules are a pyrimidine, the two reacts to form a direct covalent bond. The sole reason for wrapping with aluminum foil is to protect the bacterial DNA from the effect of ultra-violet highlighted above. The exposure time which led to visible realization of death was after 48 Hrs 10 Minutes. At this time the number of the remaining bacteria could be counted, meaning that most of them had succumbed due to the effect of the UV on them. It was evident that not all the bacteria died as a result of exposure to the UV radiation.

Like any other microorganism, bacteria can sense and is capable of adapting to the changes in its immediate environment. Bacteria forms endospores (proteinaceous coat surrounding the spore and provides resistance to harsh external conditions).With this the bacteria is capable of surviving harsh environmental conditions that would kill them. The stress of which UV radiation is part of can therefore be overcome through endospore formation which was the case for those that survived after the massive death.

According to (Pommerville,2007)Spores lacking the