Answer is 56 protons and 56 electrons.
<em>Explanation;</em>
Atomic number is equal to number of protons. Hence, when the atomic number is 56, it means that atom has 56 protons.
When the element is in neutral state, number of protons = number of electrons. Hence, we can say that barium atom has 56 electrons.
But same element can have different number of neutrons. Those are called isotopes. Hence, we cannot say that there are 56 neutrons in barium atom without having its mass number. (Mass number = number of protons + number of neutrons)
The building blocks of protein are amino acids.
Amino acids are a class of organic compounds that contain at least one amino group, -NH2, and carboxyl group, -COOH.
Alpha amino acids , RCH(NH2)COOH, are the building blocks from which proteins are constructed.
The NH group of one amino acid and the COOH group of the other amino acid are joined together and a peptide bond -CONH- is formed between the two amino acids and the product is called a dipeptide.