proving DNA replication is semi conservative

• DNA replication is semi conservative

  each new strand is made of one original strand and one new strand
• Messhelson and Stahl came up with this
• they ran expirements using bacteria to cultivate generation in nitrogen 15
• after 1 replication the DNA band was intermediate it was twice the thickeness- twice as much DNA
• after two replications in light nitrogen intermediate and light bands were observed which preoves that DNA replication is semi conservative
• DNA contains lots of nitrogen
• when drawing the strands add the old ones to the outside