More than amino acids linked together is considered a protein.

Over 50 amino acids in a chain are considered a protein.

More than 100 amino acids linked together is considered a protein.

Explanation:

The scientists categorize the links of amino acids based on the number of aminoacids:

Peptides: two to ten amino acids  

Polypeptides: 11 to 100 amino acids

Proteins are 100  and more of 100 amino acids.

A protein is a chain of amino acids linked by peptide bonds.  They are responsible of the biochemical reaction of cells.

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.