Dna replication

What type of replication is DNA replication

Semi-conservative replication

Why does DNA replicate

DNA copies itself before cell division so each new cell can get the full amount of DNA

What makes replication semi-conservative

Half of the strands in each new DNA molecule are from the original DNA molecule meaning cells produced inherit genes from their parent cells creating genetic continuity between generations of cells

3 main steps to dna replication

.Separating the strands

.Forming new strands

.Joining strands

How do dna strands separate

The enzyme dna helicase breaks the hydrogen bonds between the bases of the 2 polynucleotide DNA strands making the helix unwind to form 2 single strands

How are new strands formed

Each original strand acts as a template for a new strand and complementary base pairing means the free floating DNA nucleotides are attracted to their complementary exposed bases on each original template strand

How are the nucleotides and strands joined

Condensation reactions join the nucleotides of the new strands together – a reaction catalyzed by the enzyme DNA polymerase with hydrogen bonds forming between the bases on the original and new strands

What are the 2 ends of every dna strand and how are they arranged

Each strand has a 3’ (3 prime) and a 5’ (5 prime) end and in a double helix the two strands are antiparallel, so they run in opposite directions

How does dna polymerase interact with the ends of dna strands

The active site of DNA polymerase is only complementary to 3’ so nucleotides can only be added to the 3’ end so new strands are made in a 5’ to 3’ direction and templates are red in a 3’ to 5’ direction