The bacterium methylophilus methylotrophus can use methanol and ammonia for protein synthesis. the glutamate dehydrogenase gene from e. coli was introduced into m. methylotrophus using recombinant dna techniques. under high ammonia conditions, the introduction of the glutamate dehydrogenase gene into m. methylotrophus resulted in an increase in protein yield. select the statements that are reasonable explanations for the increased protein yield in the modified m. methylotrophus. a. glutamate dehydrogenase catalyzes the formation of glutamate and glutamine in a two-step process. b. both glutamate and glutamine play a key role in amino acid synthesis, thus an increase in levels of glutamate and glutamine increase protein synthesis. c. glutamate dehydrogenase has a low affinity for nh^+_4, and can only catalyze the formation of glutamate from alpha-ketoglutarate and nh^+_4, when the concentration of nh^+_4 is high. d. glutamate dehydrogenase has a high affinity for nh^+_4, thus the rate of glutamate synthesis increases exponentially under high ammonia conditions. e. glutamate is the amino group donor for most transamination reactions involving amino acids, thus an increase in glutamate concentration increases protein synthesis.