Protein synthesis takes place in every single living cells. All 20 amino acids are needed for protein synthesis. Protein degradation involves many different proteases, such as calpains and cathepsins. The exact mechanisms are not known. The former will release ammonia which must be disposed of through urea cycle.
Transamination is a process which nonessential AA are made.
Only two AA are strictly ketogenic. Four AA are both glucogenic and ketogenic. These include isoleucine, phenylalanine, tyrosine and tryptophan. All other AA are glucogenic. Urea cycle requires the coordination of two different tissues.