Question

each amino acid has a different variable group. the amino group of one amino acid can bond with the carboxyl group of another amino acid. this bond is called a peptide bond. many amino acids that are joined by peptide bonds form a protein.
levels of protein structure
the order of amino acids in a protein is the proteins primary structure. the amino acids can interact to form coils and bends in the chain. this is the proteins secondary structure. the bent and coiled chain can further fold to form the proteins tertiary structure.
most proteins contain several chains of amino acids. the combination of different amino acid chains in a protein makes up its quaternary structure.
the structure of a protein affects its function. because amino acids can be joined in any order, proteins can have many different structures. this variety in structure allows proteins to perform many different functions.

Explanation:

For the first question, looking at the amino - acid structure diagram and the text, all amino acids have an amino group (\( - NH_2\)), a carboxyl group (\( - COOH\)), and a hydrogen atom (\( - H\)) attached to the central carbon atom.
For the second question, according to the text "The order of amino acids in a protein is the protein's primary structure".

Answer:

1. All amino acids have an amino group (\( - NH_2\)), a carboxyl group (\( - COOH\)), and a hydrogen atom (\( - H\)) attached to the central carbon atom.
2. The order of amino acids in a protein.