Ornithine serves three metabolically important roles, but is not found in proteins. what is one of the important roles of ornithine?
a. amine donor for many transamination reactions
b. an intermediate in the urea cycle
c. involved in the synthesis of serine, which serves as a precursor for glycine and cysteine
d. its reaction with methenyl tetrahydrofolate produces lysine
e. none of the above

Astudent made the lewis dot diagram of a compound as shown. mg is written with two dots shown on its top. an o is written on each side of mg. each o has six dots around it. an arrow is shown from one dot on mg toward the vacant space around the o on the right. another arrow is shown from the other dot on mg toward the vacant space around the o on the left. the title of the art is students lewis dot model. what is the error in the lewis dot diagram? an o atom should transfer all its six electrons to mg because the formula is mgo. both electrons of mg should be transferred to one o atom because the formula is mgo. the electrons should be transferred from each o atom to mg because mg has fewer electrons. the number of dots around mg should be four because it has to transfer two electrons to each o.