5. The neurotransmitter acetylcholine (ACh) is made in the cytosol and then tran

Question

5. The neurotransmitter acetylcholine (ACh) is made in the cytosol and then transported into synaptic vesicles, where its concentration is more than 100-fold higher than in the cytosol. Synaptic vesicles taken from neurons can take up additional ACh if it is added to the solution in which they are suspended, but only in the presence of ATP. Na+ ions are not required for ACh uptake, but raising the pH of the solution increases ACh uptake. Furthermore, transport is inhibited in the presence of drugs that make the membrane permeable to H+ ions. Suggest a mechanism for ACh transport that is consistent with all these observations.

6. The second law of thermodynamics states that systems will change spontaneously toward arrangements with greater entropy (disorder). Living cells are intricately ordered, however, that it seems they must violate the second law. Explain briefly, and in a way your friends and family can understand, how life is fully compatible with the laws of thermodynamics.

7. The electron transport chain is relatively inaccessible to experimental manipulation in intact mitochondria. After disrupting mitochondria with ultrasound, it is possible to isolate functional sub-mitochondrial particles, which consist of broken cristae that have resealed inside out into small closed vesicles. In these vesicles the components that originally faced the matrix are now exposed to the surrounding medium. How could such an arrangement aid in the study of electron transport and ATP synthesis?

Explanation / Answer

5. Vesicilar acetylcholine transferase transports ACh from the cytosol into the synaptoc vesicles against its concnetration gradient (means it needs active transport). Given that this transport needs ATP and is inhibite in the prsence of drugs hat make the membrane permeable to H+ ions. So, this tranport requires "proton- pumping ATPase (counter transport of H+ and ACh occurs)."

Related Questions

Navigate

• Browse (All)
• Browse 5
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.