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Every cell contains a complete copy of “the blueprint of life” DNA consists of two strands of nucleotides - 4 bases (A,G,T,C) 23 pairs of chromosomes If unwound and tied together, human DNA in one cell would stretch ~ 5 feet, but would be only 50 trillionths of an inch wide! Genes are specific sequences of DNA, each of which “codes” for a protein with a specific function Genes are copied each time a cell divides, passing on the blueprint