How is AMP "recharged" to become ATP in a cell?

Question

I understand that after the translation stage of ribosomal protein synthesis, tRNA molecules are floating in the cytoplasm without attached amino acids until they find the correct aminoacyl tRNA synthetase enzyme which revitalizes them. However, in this process the enzyme takes an ATP molecule and returns an AMP (not ADP) molecule. It's been my understanding that an ATP's energy is normally harnessed via removing a single phosphate group and leaving an ADP molecule. Processes like respiration and photosynthesis deal with the conversion of ATP to ADP and vice versa. I understand that in removing the extra phosphate group to get an AMP more energy is released, but that also means that more energy has to be used to convert the AMP to ATP. Does the cell convert the AMP to ADP, which will ultimately become ATP in respiration, or does the cell use some retrofitted respiration/metabolism to revitalize the AMP? I would expect the first option but it would take energy (most likely from an ATP) and I would expect the amount of energy released from an ATP becoming an ADP to be different from the amount of energy released from an ADP becoming an AMP (so an ATP becoming an ADP would take more or less energy than would be required to make an AMP become an ADP, leading to inefficiencies). The other possibility (that I can see) is that the AMP is just used as a nucleotide in DNA and RNA, but I don't think that the numbers add up there. I've looked around but I can't find an answer. So how do cells convert AMP to ATP? Also I was told that the ATP to ADP conversion is the general power-conversion. Is that not the case, or is this just some rare occurrence when AMPs are involved in power conversions?

Answer 1

AMP + ATP >2 ADP (adenylate kinase in the opposite direction)

2 ADP + 2 P_i >2 ATP (this step is most often performed in aerobes by the ATP synthase during oxidative phosphorylation) AMP can be converted into IMP by the enzyme myoadenylate deaminase, freeing an ammonia group.

Answer 2

AMP Molecule. Adenosine monophosphate, also known as AMP, is the product of adenosine condensation with a single phosphate group: AMP can be producedduring ATP synthesis by the enzyme adenylate kinase by combining two ADP molecules: 2 ADP > ATP + AMP.An enzyme called ATP synthase is embedded in the inner mitochondrial membrane. The protons diffuse through the ATP synthase, which uses the energy from the proton motive force to add a phosphate group to ADP molecules available in the matrix inside the inner membrane.Adenosine-5'-triphosphate (ATP) is comprised of an adenine ring, a ribose sugar, and three phosphate groups. ATP is often used for energy transfer in the cell. ATPsynthase produces ATP from ADP or AMP + P_i. ATP has many uses.