A6-year-old child ate a peanut butter sandwich at snack time in school. five minutes later, her throat became swollen and she collapsed. this allergic reaction occurred because her body (1) recognized an antigen in peanut butter and produced antibiotics against it (2) digested the white blood cells that can recognize an antigen in peanut butter (3) did not recognize an antigen in peanut butter and could not produce antibodies against it (4) recognized an antigen in peanut butter and produced an immune response

The empty trna moves off and picks up another matching amino acid from the cytoplasm in the cell. the anticodon of the trna, with its attached amino acid, pairs to the codon of the mrna, which is attached to a ribosome. this sequence is repeated until the ribosome reaches a stop codon on the mrna, which signals the end of protein synthesis. the ribosome forms a peptide bond between the amino acids, and an amino acid chain begins to form. when a second trna with its specific amino acid pairs to the next codon in sequence, the attached amino acid breaks from the first trna and is bonded to the amino acid of the second trna.