In the citric acid cycle, how many molecules of ATP are produced per molecule of acetyl CoA that enters the cycle?
This is a typical MCAT question in which you need to be very careful not to get tricked. Instinctively, you might want to say 34 ATP since you've passed glycolysis at this point so you know the ATP be result should be higher than the 2 ATP expected from glycolysis. However, the question is specifically asking about the products of the citric acid cycle. In that context, the Acetyl-CoA molecule will produce 1 GTP, 3 NADH, and 1 FAHD2 per molecule along with 2 CO2 molecules. The GTP is easily converted to ATP and that's the answer: the citric acid cycle produces 1 molecule of ATP per each molecule of Acetyl-CoA. The traditional 34 ATP production comes from the electron transport chain which will use the electron carriers NADH and FAHD2 to produce the additional ATP molecules associated with aerobic respiration through oxidative phosphorylation.
What are the differences and similarities of Hemoglobin and Myoglobin?
Hemoglobin and Myoglobin are both proteins that can bind to oxygen via a prosthetic group called heme. An Iron atom along with Histidine amino acids within the protein structure stabilize the oxygen molecules. The major similarity between the two is the protein 3D structure which has a globular shape, hence their names. However, hemoglobin is composed of two dimers(two structural units) which makes it a tetrameter(4 structural unit) while myoglobin is a monomer(one structural unit). When it come to function, hemoglobin is used in the bloodstream to transport oxygen throughout the body while myoglobin is used to store oxygen in muscle tissue to be use for energy production. A good way to remember the difference in function is by knowing the meaning of prefixes. In this case, as you might imagine, HEM- usually referes to blood while MYO- refers to muscle.
What aspects should I work on through my high school career to stand out as a college applicant?
Applying to college is a balance between many areas. You need to maintain a consistently positive academic performance by getting mostly A's and B's, specially during your final years of high school. You also need to challenge yourself through your class selections. Furthermore, it is important to prepare yourself and perform well on a standardized exam such as the SAT or the ACT. Finally, an often overlooked aspect is the importance of fostering extracurricular activities and personal interests outside of academic setting. This is an area where you will have great potential to stand out from the crowd and strengthen your application by becoming an interesting and well-rounded candidate. Another important thing to keep in mind is to invest in activities that will highlight desirable traits such as leadership roles and volunteering. Untimely, be yourself, invest in your interests and make sure you check all the boxes when it comes to academic standards.