Evidence for Semi-conservative Replication (AQA A-Level Biology): Flashcards
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Semi-conservative replication definition
Semi-conservative replication definition
Each new DNA molecule has 1 original strand + 1 newly synthesized strand
Conservative model of DNA replication
Conservative model of DNA replication
Original DNA intact, new copy made from entirely new material
Nitrogen isotopes used in Meselson-Stahl experiment
Nitrogen isotopes used in Meselson-Stahl experiment
N (light) and N (heavy)
Method to separate DNA by density
Method to separate DNA by density
Density gradient centrifugation
Meselson-Stahl generation 1 DNA density result
Meselson-Stahl generation 1 DNA density result
All DNA showed intermediate density (hybrid)
Meselson-Stahl generation 2 DNA density result
Meselson-Stahl generation 2 DNA density result
50% intermediate, 50% light
Why intermediate density disproves conservative model
Why intermediate density disproves conservative model
Conservative would show 2 distinct bands, not 1 intermediate
Element in DNA bases tracked in Meselson-Stahl
Element in DNA bases tracked in Meselson-Stahl
Nitrogen
Complementary base pairs in DNA
Complementary base pairs in DNA
A with T, G with C
Where bacteria get nitrogen for DNA synthesis
Where bacteria get nitrogen for DNA synthesis
From their growth medium