Afight-or-flight response is to humans because it

The fight or flight response results in certain physiological responses that would be of benefit in a situation of life or death.  The neural response results in the adrenal gland releasing the hormone epinephrine. This results in the release of additional energy, which provides a temporary energy boost. Other changes to facilitate violent muscle reactions include:  heart acceleration, diversion of blood to the most important organs, liberation of excess energy, and dilation of blood vessels for muscles. It is arguable that in a situation of violence, such as self defence, previous exposure to controlled violence, such as martial arts training, would be of more benefit, as these physiological changes can be controlled and channeled for the best results. 

Proteins are the workhorses of the cell, controlling virtually every reaction within as well as providing structure and serving as signals to other cells. proteins are long chains of  amino acids  , and the exact sequence of the amino acids determines the final structure and function of the protein. instructions for that sequence are encoded in  genes  . to make a particular protein, a messenger ribonucleic acid (mrna) copy is made from the gene (in the process called  transcription  ), and the mrna is transported to the  ribosome  . protein synthesis, also called  translation  , begins when the two ribosomal subunits link onto the mrna. this step, called initiation, is followed by elongation, in which successive amino acids are added to the growing chain, brought in by transfer rnas (trnas). in this step, the ribosome reads the  nucleotides  of mrna three by three, in units called  codons  , and matches each to three nucleotides on the trna, called the anticodon. finally, during termination, the ribosome unbinds from the mrna, and the  amino acid  chain goes on to be processed and folded to make the final, functional protein