Ch 9: Cellular Respiration and Fermentation Three people are murdered. The first
ID: 212518 • Letter: C
Question
Ch 9: Cellular Respiration and Fermentation Three people are murdered. The first is poisoned with cyanide, a toxin that mimics oxygen. The next is fed a peanut that he is allergic to. The third is shot with a magic laser that causes all of the ATP in the body to dephosphorylate. Explain why the three deaths feel similar to each other, some physiological effects the cells are experiencing that leads to death in each case, and which stages of cellular respiration are/aren't impacted for each assaination.Explanation / Answer
In cellular respiration, oxygen acts as a final electron acceptor in the electron transport chain (ETC). The ETC has series of molecules present on inner mitochondrial membrane. These accept electrons and protons from the Krebs or TCA cycle. The electrons are passed through these molecules and combine with protons (H+) and oxygen to form water. In this process, ATP is generated by ATP synthase. Electrons cannot be transferred if oxygen is absent. Cyanide prevents binding of oxygen to the electron, there preventing formation of water and ATP. Hence, these individual will die of oxygen deprivation despite adequate oxygen being present in the cells. Thus, cyanide affects the electron transport chain in mitochondria by mimicking oxygen. As less ATP is available, muscles will contract faster and cannot relax, affecting breathing.
Peanut allergy is due to binding of the allergen to IgE that activates mast cells and/or basophils, inducing an immune response. Mast cells and basophils release histamine when activated, resulting in anaphylaxis. Anaphylaxis is an allergic reaction that results in release of molecules by the immune system that decreases blood pressure and blocks the airways to stop breathing. Breathing is blocked due to effect on smooth muscle contraction. It causes vasoconstriction due to contraction of muscle wall.
Histamine release requires energy input in form of ATP. Hence, release of histamine is inhibited by cyanide. Uncoupling of oxidative phosphorylation is the mechanism by which cyanide inhibits histamine release during anaphylaxis.
When ATP is continuously dephosphoryaled, it is converted to ADP and Pi. Hence, all ATP will be used up by the cells. As a result, the body no longer has ATP to carry out catabolic processes that required ATP. Muscle contraction is affected and the myosin and actin will remain in bound state, causing continuous muscle contraction. This will cause stiffening of the muscle. Hence, respiration will be affected as the respiratory tract muscle will be affected, affecting breathing. Cellular respiration will slow down in functioning as ATP is not available for breakdown of glucose.
The three deaths feel similar to each other, because all of them affect cellular respiration. All three deaths will also be a result of declined breathing due to effects on muscle contraction. The magic laser affects glycolysis and cyanide affects the electron transport chain. Peanut allergen will increase oxidative phosphorylation for increased histamine release.