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Esterification and IR Spectroscopy

Submitted by mrmoy on Thu, 04/12/2018 - 19:56

To a 5 mL round-bottomed flask was added propanoic acid (0.975 mL), 1-propanol (0.82 mL), 4 drops of concentrated sulfuric acid, and a few boiling chips. After being mixed thoroughly, the solution was brought to a gentle boil after the apparatus was set up to a 45˚ angle. After the solution was refluxed for 15 minutes, the apparatus was removed from the heat and was tipped back so about ½ to ¾ of the upper organic phase in the side arm returned back into the flask.

Medical Ethics

Submitted by lgorman on Thu, 04/12/2018 - 18:59

Thomson takes it a step further by saying if the woman has bars installed but the robber still gets in through her open windows, it would be absurd to call it her fault that the robber got in. However, when women get pregnant because of malfunctioning birth control, they are often seen as voluntarily getting pregnant. Thomson also brings up the people-seed scenario, where there are people-seeds floating around outside, so you install very fine mesh screens to prevent them from getting in once you open your window. However, when one gets past the screen and takes root in your house, Thomson asks if it is your responsibility to keep the plant. The only way to really prevent those seeds from getting in, is to never open your windows in the first place. In summary, Thomson is saying that there are scenarios where the fetus has right to its mother body, and some scenarios where it doesn’t. It is impossible to make a blanket statement specifying when a pregnancy is voluntary or involuntary and when an abortion is just or unjust.  

 

Medical Ethics Draft

Submitted by lgorman on Thu, 04/12/2018 - 18:58

On pages 58-59, Thomson writes about how some opponents of abortion support the independence of the fetus, and how the fetus has a right to the mother’s body when it was conceived through voluntary intercourse. People often say the only case of involuntary pregnancy comes from rape. However, Thomson writes that it is a slippery slope to choose when a woman voluntarily or involuntarily becomes pregnant, as details can make a huge difference. First, Thomson describes a scenario where a woman opens her window because her room is stuffy, which allows a burglar to get in. Thomson then says how absurd it would be to say that the burglar has a right to stay in the room now that they have gotten in, even though the women technically allowed him to get in by opening her window. Although that may be absurd, a parallel could be drawn between this situation and woman becoming pregnant.

Isolation of trimyristin from nutmeg discussion part 2

Submitted by jonathanrubi on Thu, 04/12/2018 - 17:25

Melting point of the once recrystallized product was determined to be 53-55oC. The melting point of the twice recrystallized product was determined to be 54oC. In literature, the melting point of trimyristin was 57oC. The narrowing melting point range after each recrystallization indicated a relatively pure product formed from recrystallization. The slightly lower melting point obtained versus in literature indicates some soluble impurities present. The product of the hydrolysis and acidification of trimyristin was determined to be myristic acid using melting point analysis. Melting point of the myristic acid was determined to be 51-52oC and the literature value of expected melting point of myristic acid was 54oC. The slightly lower melting point obtained as well as the narrow melting point range indicate subtle impurities.

Isolation of trimyristin from nutmeg discussion part 1

Submitted by jonathanrubi on Thu, 04/12/2018 - 17:24

In this lab trimyristin was isolated from the organic compound nutmeg in the presence of tert-methyl butyl ether. The crude trimyristin product was then recrystallized in the presence of acetone and hydrolyzed in the presence of sodium hydroxide and 95% ethanol and then acidified in the presence of hydrochloric acid. Recrystallized trimyristin was recrystallized a second time in the presence of acetone. The recrystallized product was determined to be trimyristin using melting point analysis with a yield of 23.7% after the first recrystallization and 6.0% after the second recrystallization based on the original amount of nutmeg used in the reaction.

Isolation of trimyristin from nutmeg procedure

Submitted by jonathanrubi on Thu, 04/12/2018 - 17:23

         To a round-bottom flask was added nutmeg (1.00g) and tert-butyl methyl ether (3mL). Heating at boiling point was performed to the solution for 10 minutes. Micro-scale filtration was performed on the solution. Crude product was recrystallized from acetone (2mL) and cooled. To a round-bottom flask was added recrystallized trimyristin (60mg), 6M NaOH (2mL) and 95% ethanol (2mL). The solution was refluxed for 45 minutes. The solution was allowed to cool and poured in a beaker containing water (8mL). To the solution was added HCl (2mL) dropwise and stirred while cooled. Remaining recrystallized trimyristin was recrystallized from acetone (2mL). Melting point of product and both recrystallized trimyristin was determined.

 

The end replication problem - conclusion

Submitted by jonathanrubi on Thu, 04/12/2018 - 17:22

In contrast, experiments have shown that a reduction in telomerase activity and the shorting of telomeres has been associated with aging. This highlights the importance of the maintenance of telomere length and protection in control of the cell cycle life span. Further research on the mechanism of telomere maintenance and shortening could provide important information regarding the development of cancer treatment, anti-aging strategies, and hereditary disease function. As the average life span of humans rapidly increases, research in this field will become even more important. 

The end replication problem - cancer and aging

Submitted by jonathanrubi on Thu, 04/12/2018 - 17:22

More insight into the mechanism behind telomere maintenance and replication shed light on its role in cancer as well as aging. It was discovered that in 80-90% of cancers, an increase in telomerase activity can be shown. This indicates the role telomere shortening may play in preventing unwanted mutations and cancer. Once cells divide a certain number of times in healthy cells, unprotected and shortened telomeres trigger senescence and apoptosis. With overactive telomerase, this shortening is prevented and cells would be able to proliferate uncontrollable and an unlimited number of times.  This mechanism of induced senescence and apoptosis in cells with improper telomere function appears to be regulated by the tumor suppressor gene p53, which acts by binding damaged DNA and promotes p21 activity, a CDK inhibitor which induces cell arrest pathways. Since p53 function is inhibited in 70-80% of cancers, this provides a major hurdle for biologists moving forward in targeting drug therapies towards cancer cells with impaired telomeres.

The end replication problem

Submitted by jonathanrubi on Thu, 04/12/2018 - 17:21

The “end-replication problem” is one that puzzled many molecular biologists and biochemists for decades. Since a free 3’ OH group is needed for DNA replication and a new strand of DNA to be synthesized, this creates a problem for the ends of linear DNA molecules, such as those we see in eukaryotic cells. Investigation into this mystery began when Blackburn and Szostak sequenced the ends of linear DNA molecules from Tetrahymena and were able to ligate to the ends of yeast cells DNA. These experiments showed evolutionarily conserved properties of Tetrahymena rDNA end sequences with those similar sequences in yeast cells that led to functional telomeres. They were also able to identify repeated C1-3A sequences in telomeres of both organisms. As a graduate student in Blackburn’s laboratory, Greider was able to identify G-rich rDNA molecules in Tetrahymena that contained the necessary 3-OH group for DNA replication that was complementary to the repeats seen in the telomere sequences. The addition of the G-rich oligonucleotide were also shown in vitro to enzymatically be added to yeast telomeric DNA. At this point, the scientists were able to establish a mechanism for telomere synthesis and maintenance involving the enzyme telomerase as a unique reverse transcriptase with an RNA template and protein components, the mystery had been solved.

End Replication Problem Intro

Submitted by jonathanrubi on Thu, 04/12/2018 - 17:20

In 2009 the Nobel Prize in Physiology or Medicine was awarded to three scientists for their discovery and research in telomeres and the enzyme telomerase. Since Watson and Crick published the structure of our DNA and Meselson and Stahl discovered the mechanism by which our DNA is replicated, a mechanism for how the ends of chromosomes can be replicated and maintained. 

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