Blueprint MCAT (formerly Next Step Test Prep) That said, memorize the Krebs cycle backwards and forwards first and then remember all the key steps in all the other reactions. You don’t have to list every single step in glycolysis on the MCAT. You should be able to list every enzyme in the Krebs cycle, every substrate that gets acted on by the enzyme, and all the coenzymes and cofactors, all the inputs and the outputs.Īs for any pathway in the body, just generally know the inputs and outputs and the regulatory steps. In terms of the Krebs cycle and all the different energy pathways, you have to know them backwards-forwards, upside-down. Contextualize it.ĭon’t skip this first step because just from the names of the molecules, and recognizing the general situation, you can take a pretty good crack at the question. But when it comes to actually answering questions on test day, just put it in the big picture. Quick Tips for Answering Biochemistry Questionsįirst, understand what the question is asking since students get very hung up in metabolism and biochemistry, trying to memorize a million names of enzymes, substrates, etc. You would want to activate that whole chain of connections. If you have tons of energy and you want to store that energy, you would actually bump up your ATP citrate lyase. The enzyme basically converts the citrate to acetyl CoA, which goes over and the body makes fat molecules out of it for storage. Hence, you switch off glycolysis by switching off pyruvate kinase, the enzyme in the end.ĪTP citrate lyase is a key enzyme that links carbohydrate metabolism (the Krebs cycle) to fat anabolism (making fat). If you shut that off in the end and if you have tons of ATP floating around, you don’t need to make more energy. Remember that pyruvate is that last step in glycolysis so the key regulatory point when you wrap up glycolysis before you head over to the pyruvate dehydrogenase complex or Krebs cycle, you regulate glycolysis right at the end there. So you don’t want to pick the activation choices, leaving us here with A and C. In response, you slow your Krebs cycle and all that mechanics down. The cell is in a really high energy state, which means you don’t need to make any more. (B) Activation of phosphofructokinase 1.Question 47: ATP/ADP RatioĪ cell in which an elevated ATP/ADP ratio exists is most likely to demonstrate which allosteric effect resulting for this elevation? So you have to go to the periodic table and see what’s element number 8 and you would see that it’s Oxygen. Fluorine which had 9 protons went down to only 8 protons. If shot off a positive charge, it means that one of it is positive, so the proton became a neutron. So if Fluorine starts with a mass of 18, shooting out a positron is not going to change the 18 at all because it didn’t give out any mass. Relative to a proton, you can treat beta decay as having a zero mass. So beta- is an electron while beta+ is a positively charged electron. It’s a position which is a fancy name for a positively charged electron. It doesn’t give you much except for the atomic number and then the element itself.įirst, you need to know the weight of a beta+ particle. The test would give you a periodic table where you click on the button in the corner of the screen. What does 18F become after a beta+ decay? In fact, in the Next Step Full Length analysis, about 65% get this question right while the other 35% all pick the aorta. If you’re not reading this question very carefully, you might pick (A) Aorta. So it’s in the capillaries that the blood flows the slowest that it almost comes to a standstill so that your oxygen and carbon dioxide can get exchanged. The blood in the aorta and the arterioles is just rushing along because of all that pressure from the heart. The question also says lowest fluid velocity. There are tens of thousands of capillaries for every arteriole, much less for the aorta and vena cava in the body. Within the body, which of the following blood vessels is expected to have the greatest total cross-sectional area and the lowest fluid velocity? Chylomicrons are the little clumpy bits that are used to transport fatty acids throughout the blood. So a glycerol backbone plus three fatty acids make up a full classic E-shaped triacylglycerol or just just fat molecule. Glycerol is the three-carbon backbone and fatty acids are the little tails that get tagged onto the glycerol. Also check out all our other podcasts on MedEd Media.Ĭlick Here to Download Handout Question 44: Fat Moleculesįats are stored in adipose tissues primarily as: We are once again joined by Bryan Schnedeker from Blueprint MCAT (formerly Next Step Test Prep). ATP, blood vessels, fat stores and beta decay are the topics we cover in the next set of discrete questions from Blueprint MCAT (formerly Next Step Test Prep) Full-length 10.
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