Question

main product of protein and carbohydrates after digestion

Answer 1

Protein consists of a series of Amino Acids that are linked together with peptide bonds to form a complete protein. 

When you eat food, an enzyme in your stomach called pepsin breaks the peptide bonds to separate the proteins into smaller groups of amino acids called polypeptides, which are broken down further by other enzymes: trypsin, chymotrypsin, carboxypeptidase, throughout their journey through your stomach and small intestines.

These amino acids are the final product of protein digestion.[2]

There are 22 amino acids that our bodies make use of to make proteins and other molecules.

Essential amino acids cannot be synthesized by our body and to get them we must get them from foods:

Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine

Nonessential amino acids can be synthesized in humans from other compounds:

Alanine
Arginine
Aparagine
Aspartic Acid
Cysteine
Glutamic Acid
Glutamine
Glycine
Proline
selenocysteine
Serine
Tyrosine

After protein is broken down into polypeptides, then peptides, then amino acids, the amino acid molecules are small enough to be absorbed into the lining of the small intestine and enter the blood stream.