B3 - DNA Replication

The steps that DNA takes to replicate itself. Needed for your biology ocr exam.

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Step 1

DNA needs to replicate itself every time a cell divides. This is because that cell needs the full amount of DNA.

The first step is;

The double helix "unzips" itself. This forms two single strands.

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Step 2

New nucleotides, which float freely in the nucleus, join on using complementary base pairing.

This is where A always goes with T, and G always goes with C.

This means that you get an exact copy of the DNA on the other strand that it was split with in step 1.

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Step 3

Cross links form between the old DNA strand and the bases, so that the nucleotides are joined together.

This forms double strands.

Now, the DNA strands are identical to what they started out as, meaning that the DNA has replicated itself.

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The Key Words From This Section

  • DNA (made up of genes)
  • Double helix (double stranded spiral)
  • Nucleotides (contain bases)
  • Bases (A, T, C, G)
  • Complementary base pairing (A with T, C with G)
  • DNA replication (where DNA copies itself)
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