acid adenine background biochemistry biology biotechnology blue cell chemistry chromosome clone cloning cytosine dark deoxyribonucleic dna double education evolution gene genetics guanine health helix human illustration lab life medical medicine microscopic molecular molecule organic pharmaceutical pharmacy research ribonucleic science scientific spiral stem strand symbol technologies technology test therapy thymine concept bushes dog Florida labrador palmettos portrait retriever trees yellow carnivore collar Companion dog Dog breed Dog collar fawn snout snow whiskers circle grass green groundcover plant bite casting crown dentistry fixture gums impression jaw molar mold molded molding plaster repair teeth tooth