chromosomes Chromosomes are arranged in order of size from largest to smallest. This is called a karyotype.   DNA Replication DNA must make a copy of itself prior to cell division. The cell cycle diagram labels this time in the life of the cell, the "S" phase. The S is for synthesis.   DNA transcription The DNA must stay in the nucleus for safekeeping of the code. A temporary copy of a gene is made, called mRNA.   DNA translation tRNA is the adaptor molecule, bringing the correct amino acid for the three letter codon of the mRNA      Dolan DNA Learning Center - Gene Almanac  DNA from the Beginning  Your Genes, Your Health  Image Archive of the American Eugenics Movement  Access Excellence  Biointeractive     More...