Which 2 amino acids donate amino groups to other compounds for nitrogen metabolism? What citric acid cycle intermediate can be converted to aspartic acid upon acceptance of an amino group? What coenzyme shared by pentose phosphate pathway and by lipid biosynthesis is also used to make glutamate? What citric acid cycle intermediate is produced during the urea cycle? Name 3 standard amino acids found in the urea cycle and indicate if they are a) polar neutral, b) acidic, c) basic, d) hydrophobic. What are the 2 nonstandard amino acids in the urea cycle?