Which is an optically inactive amino acid?

Serine $(HOCH_2CH(NH_2)COOH)$ is an amino acid. The correct Fischer projection of $L$-serine is:

At the isoelectric point:

Write a note on amino acids.

In the given pentapeptide, find out an essential amino acid $(Y)$ and the sequence present in the pentapeptide: Choose the correct answer from the options given below:

Which of the following metals forms a complex with insulin?