I need more information as to why I and III are correct. Thank you O Chopin: Son
ID: 132539 • Letter: I
Question
I need more information as to why I and III are correct.
Thank you
O Chopin: Sonata No.3?× y, ? Dietary supplements for s i, e Chegg Study | Guided Su x ? | Secure! https://www.khanacademy.org/test-prep/mca ces-practice-tut/efarnino-acids-and-proteir MCAT> BIOLOGICAL AND DIOCHEMICAL FOUNDATIONS OF LIVING SYSTEMS PASSAGES Dietary supplements for building up muscles Biological sciences practice passage questions mutations resUitin Dictary branchcd chain amino acids (BCAmarkcted to athlctcs as a supplemcnt that stimulates protcin ormatiorn in muscle and reduces muscle breakdown. Brached-chain amino acids are those amio acicds thathave a side chain consisting of an aliphatic group with a branich point,including leucine, isoleucine, and valine Tigure 1). They account for 35% of the essential amino acids found in muscle proteins. Osteogenesis Practice: Dietary Figure 1. Branched chain amino acid propertics building up muscles pKa amino group 9.74 9.76 9.74 pKA carboxyl group 2.30 2.32 2.32 Amino Acid group Practice: Fighting the flu with Oseltamivir CHICH3) Valine Isoleucine CHICH3)CH2CH3 Leucine CH2CIHICIH) Practice: ACE inhibitors and the renal regulation of bload pressure The medication rapamycin has important immanosuppressive effects and its mechanism has been well studied. The mammalian target of rapamycin (mTOR, is aconserved serine/thrennine protein kinase that regulates protein metabolism. mTOR integrates intracellular inputs such as growth factors (in particular BCAA amino acids to promotc protcin translation. Activated mTOR results in the phosphorylation of a translation initiation protcin called elF-4EBP1.Unphosphorylated elF-4EBP1 blocks trarnslation by sequesterin a different tranislation initiation protein called eir4C which ri responible for binding the mRNA up and bringing th 'nRNA trar cr ipt to the ribonme Phosphorylation of elF-4FBP1 hy mTOR causeselF-4FP1 torelease elF4F. and results in the initiation of translation Practice: The discovery of leptin Practice: Disorders of theskeletal system and bone remodeling Practice: The only known case of an HIV Recently, studies in animal models havc sueecsted that certain BCAAs are more effective than others in activating mTOR (Fiure 2,gestin that nutritional supplerrients could be more ellectively largeted oward building muscde through this pathway. FiRure 2. Percerntage phosphurylated elF-4EUP1 Practice: Type 2 diabetes mellitus Show summary 4:06 PM O Type here to search ^??4:): 7/4/2018Explanation / Answer
The question and data indicates that the branched chain amino acids helps in building the body muscles and hence are added in supplements provided to athletes. The mechanism by which this happens is through the mTOR which is an enzyme (kinase) and is responsible for regulating metabolism in mammals. This protein can sense the levels of oxygen and nutrients in the cell as well as the energy available to the cell and hence adjusts the metabolic rate.
Another factor considered in the question is eIF-4EBP1 which is a protein associated with translation process. This protein prevents the assembly of 40S ribosomal subunit onto mRNA which is to be translated and hence blocks the initiation step of translation process. Now, because the translation is inhibited it limits the protein synthesis. So, in a way it prevents building muscle mass. To, inhibit this protein the phosphorylation occurs and then the normal translation can take place.
mTOR pathway which is involved in metabolism, on sensing the higher levels of branched chain amino acids (from supplements), will be initiated and causes the anabolic pathway to start and hence leads to rapid increase in cell formation by utilizing the substrate (branched chain amino acids in present case) and leads to body building. Formation of cells requires the proteins to be synthesized which in turn require translation process to take place. But for that and to initiate translation eIF-4EBP1 has to be inhibited (which is by phosphorylation).
Now, the MCQ addressed is If nutritional companies present data in figure 2, they are assuming that any increase in eIF-4EBP1 phosphorylation causes increase in protein levels (option III) and that increase in eIF-4EBP1 phosphorylation is due to mTOR pathway (Option I).
In figure 2, the increase in levels of branched chain amino acids are shown to increase the percentage of phosphorylated eIF-4EBP1. This is correct because initiation of mTOR and suppression of eIF-4EBP1, both are required together for new cell formation and hence body building. If only mTOR will be initiated the translation could not take place due to active eIF-4EBP1. As in option II, the BCAA's available can turn on mTOR but along with that inhibition of eIF-4EBP1 is also required. Alone activation of mTOR will not cause the building up process.