DNA,生命的蓝图 年g年年年g年g年年年 31 cG G The two strands of the parental double helix unwind, and each specifies a new daughter strand by base-pairing rules Old Old -AT A CG New Minor Major ●●V groove -TA TA 5 3 B.DNA(B conformation) CGDNA， 生命的蓝图