kitty_cat,
on a vegetarian diet, and by that I assume you mean a plant-based way of eating, then all the amino acids that you need to form human protein are contained within them (fruits and vegetables).

Protein needs....
"During the last sixty years, several researchers (Rose, Boyd, Berg, et al) all independently proved that between 3.7% and 4.65% of the total food intake was all the protein necessary to maintain good health. These percentages are equivalent to about 24 to 30 grams of protein.
Careful investigations by Dr. Max Rubner, director of the Hygienic Institute of the University of Berlin, showed that only 4% of the entire caloric intake had to be in the form of protein. On a 2,500 calorie diet, this is about 100 calories of protein or about 28 grams"................
http://www.rawfoodexplained.com/proteins/how-much-protein-do-we-need.html


Symptoms of protein deficiency include weakness resulting from a loss in muscle mass.
Other symptoms of protein deficiency include: weight loss, diarrhea, an accumulation of fluids (edema) in the legs and abdomen. Visible signs include hair loss, scaly skin, and lethargy due to a lack of energy.

On the other hand, excess protein places an excess burden on the Liver and Kidneys by the creation of too much uric acid.
http://www.rawfoodexplained.com/the-dangers-of-a-high-protein-diet/


Chrisb1.