Microbiology Uv Light Lab Report

1487 WordsApr 17, 20176 Pages
Name: Shannon Kelly Microbiology UV Light Lab Report Introduction: - Why does Ultra Violet light at 260nm cause the most damage to DNA? Does damage caused by UV light affect DNA in both prokaryotic and eukaryotic cells alike? UV light at 260nm causes the most damage to DNA because that is the amount of light that DNA absorbs the most light. No, UV light does not affect both prokaryotic and eukaryotic cells the same way. For example, in eukaryotic cells there are three different ways DNA can be repaired (photoreactivation, post-replication repair & excision repair), whereas in prokaryotes excision repair mechanism is used. - Explain how do pyrimidine dimers form. Pyrimidine dimers form when DNA is damaged by UV light and they form…show more content…
The damaged part of the DNA strand is nicked out by endonucleases that contain the dimer, which is then released from the DNA. After the fragment is released, DNA polymerase fills in the gap with a new strand and DNA ligase will close up the repaired strand. - Are endospores more or less resistant to UV light than vegetative cells? What accounts for this increased or decreased resistance to UV light? Endospores are more resistant to UV light than vegetative cells. Endospores have an increased resistance to UV light because of the structure (exosporium) as well as the small acid-soluble proteins found inside, which tightly bind and condense the DNA in the endospore. - Develop a hypothesis for the experiment conducted. Be sure to include how the length of exposure to UV light and the ability to form endospores affects a cells susceptibility to UV light. (If it is easier you can form two hypotheses one about how lethality is connected to length of exposure to UV light, and another about how the susceptibility of endospores and vegetative cells to UV light. 1. If there is a longer length of time the bacteria is exposed to UV light, then more cells will be killed. 2. If the bacteria exposed to UV light can form endospores, then they are less susceptible to the effects of the UV light and can survive the conditions. Methods: - Create/insert a table that includes the exposure times for each microbe used (like table 1
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