The Surplus Capacity of Enzymes in the Glycolytic Pathway - Lab Report Example

According to the paper en d ‘Flux control and excess capa in the enzymes of glycolysis and their relationship to flight metabolism in Drosophila melanogaster’ written by Walter F. Eanes, variation of enzymes in the catabolic cytoplasmic process glycolysis does influence flight performance. It is evident that Drosophila is widely and extensively studied laboratory model so its glycolytic pathway is also comprehensively considered to be the focus of the study. Glycolysis is a catabolic process so the energy released is utilized by D. melanogaster to thump or beat enabling the fruit fly D. melanogaster to employ wing muscles to beat (Sackeor, 1976). The fact is therefore established that glycolysis generates energy rich molecules called ATP which provides energy to the wing muscles to fly. Therefore, a relationship is depicted between glycolysis and flight performance. Furthermore, the study focuses on the surplus capacity of enzymes in glycolytic pathway. The key terms used in the paper encompass- WBF which denotes Wing Beat Frequency of D. melanogaster. P- element, a transposon that is capable of mutating and hence creating alteration in genome of the D. melanogaster, thereby generating modified organisms to perform genetic studies. Thus the product, protein molecule that is formed is also altered. The focus of the study encompasses- Is there a canalization of the flight performance even when there is a reduction in glycolytic enzyme activities? Does glycolytic pathway displays the excess capacity of the enzymes at its steps? The researchers pointed out about the truth flight metabolism holds in the literature, although physiologists assumed that the metabolism was fully discovered, monitoring the oxygen consumption. They even questioned about physiologists’ argument that some enzyme in the glycolysis pathway exists in the body as compared to the number of enzymes needed in the process. However, it was the explanation without any experiment which perturbs activities of enzymes in glycolysis. Therefore, to readdress this explanation in the way of the genetics with modern approach, the researchers began to have a question about the fact that was disputable between physiologists and biologists. Taking the advantage of advanced technological tools and the adequate research background, the researchers can design the experiments. Initially, they did not have high tech tools to study flight performance. This could be one of the reasons why the flight metabolism in the textbooks was not elaborated effectively. With the development of high speed camera, they decided to video record the flight performance of D. melanogaster. They also did the background research for the D. melanogaster and P-element to use them in the experiments. They established that D. melanogaster was the best to execute the above experiment. Also, they knew P-element can be used to modify the genes which result in mutation of proteins. With information mentioned, the researcher addressed the same questions. First, they wanted to find out if there would be any significant influence on glycolysis when they varied the expression of the enzyme activity. Also they wanted to find out if there would be more quantity of enzyme appearance than required for normal state of pathway, changing the activities in each enzyme. The researchers tested the questions with experimental steps. They first used P-element to modify genes of D. melanogaster, reducing the level of enzymes to 50% - 10%. Enzymes that they varied were the PGI (Phosphoglucose isomerase), PGM (Phosphoglucomutase), TPI (Triosephosphate isomerase), HEX-A (muscle specific Hexokinase), PYK (Pyruvate kinase), TREH (Trehalase) and GLYP (Glycogen phosphorylase). They decreased the activities of each enzyme to distinguish which enzyme can control the flux of glycolysis. With a view that if there is a significant decrease in flight performance, the enzyme is critical for the pathway. They placed and tethered D. melanogaster to the transparent box to video record the flight at different levels of enzymes. Finally, they counted the number of wing movement to measure the WBF (Wing Beat Frequency). Table 1 Statistical analysis for 16 experiments on flight performance As depicted in table 1, 3 out of 7 enzymes showed significant drop of WBC when the researcher decreased the activities of each enzymes. Reduction of GLYP and PGM showed significant reduction of WBF. Furthermore, reduction of HEX-A showed not only reduction of WBC but also reduced flying time and distance. Therefore, the steps in which these enzymes were involved were critical in the glycolytic pathway. This also means that these are the rate limiting steps in glycolysis. Also, as explained in the textbook even before this experiment, we can assume that HEX-A is particularly imperative enzyme to run the pathway because it showed other results that GLYP and PGM did not show. Furthermore, enzymes, except for PGM, GLYP, and HEX-A, showed no or little difference in flight performance even if the researchers decreased the activities of enzymes, as shown in the table 1. With this data, we also can conclude that muscle fibers have much more amount of glycolysis. Fig 1. Layout of glycolysis and Changes of WBF enzymes than they would need to run according to enzymes with different Glycolysis activity. The figure 1 shows layout of the glycolysis and the graphs in Figure 1 shows the changes in WBF according to varied activity of enzymes. The y-axis is the percent of WBF and x-axis is the activity of enzymes. As shown in figure 1, GYLP, PGM, and HEX-A showed significant decrease in WBF. Even if the changes made in percentages are quite small, but such alterations are capable of bringing big differences in WBC. That’s because the y-axis is representing the value of standard deviation and this small changes in standard deviation showed poor performance in flying. The questions about critical steps and excess capacity in glycolysis were well supported by the data shown above. The researchers can find out the steps with GLYP, HEX-A, and PGM were critical in glycolysis as it showed reduction of flight performance when their activity were decreased by P-element. HEX-A is also considered as a key regulation step since it showed decreased ability of flying time and distance when its activity was knocked down to low level. Furthermore, the researchers found that excess capacity of enzymes existed since most of enzymes down-expressed to low level showed normal flight performances, meaning that enzymes in glycolysis exist in excess than required by the pathway. This question gave rise to further research work, stating that we can find out the amount of enzymes stored in the body as an excess capacity, varying the enzyme activity. Also, since the D. melanogaster is the ectotherm as their metabolic rate depends upon different temperatures, we can conduct this experiment with different temperatures. Whole process of project for 2 weeks was valuable enough to change the way to interpret the papers. The process also taught me how to approach the complex biological topics by following the steps explained in lab manual. To be honest, the first time I read the papers I was completely lost because the terms shown in the paper were just hard to understand and I did not even know from where to procure the required information about the topic. I also was little nervous that I had to present this without thorough understanding of the topic. However, the steps explained in manual and podcast for interviews were extremely helpful to understand the topic with much ease. The professor who did the research also explained key terms in his paper in truly explicit manner with elaborated discussion on each criterion, the purpose, result, and conclusion of the paper. After watching the video, I read the paper again and I could understand what each paragraph was trying to imply. Before this project, I tried to focus on each tree instead of broadly focusing on the entire forest to understand the purpose and focus of the paper. I think that this was the reason why I had a hard time to read the paper for the first time. However, I could learn the way to understand the focus and issues which are discussed in the paper. This is going to be a great help to me in my entire future endeavor. I am really thankful that I was provided with the lab manual that really paved the way towards an understanding about the research and how to correlate the data and develop an indulgent with a broad perspective and a deeper outlook. With time I am sure I will develop more thoughtful ways to have a better understanding about the research in the field of Genetics. References Knisely, Karin. Marven H. O’Neal III. 2008. A Student Handbook for Writing in Biology. U.S.A: Sinauer Associates, Inc. 221 p. Sackeor B. 1976. Biochem Soc Symp Walt Eanes, Podcast #7, 2010-02-28 Read More