weirdfacts

DNA is a double helix of nucleotide chains. Adenine pairs with thymine and cytosine pairs with guanine. The sequence stores information used to produce RNA and proteins.

During semiconservative replication, the strands separate and each acts as a template. Each new DNA molecule contains one original strand and one newly synthesised strand. Replication errors can create mutations.

INTERACTIVE MODEL

DNA base pairing

ATTemplate New strandA pairs with T in DNA

Explore: Choose a template sequence and build its complementary copy.

ATCGA\leftrightarrow T\qquad C\leftrightarrow G
WORKED EXAMPLE

Find the complementary strand for A–C–G–T.

  1. Pair A with T and C with G.
  2. The complementary sequence is T–G–C–A.
Assumed knowledge

Molecules and information.

Learning checkpoints & sourceYOUR LEARNING CHECKPOINT
  • Apply complementary base pairing.
  • Explain semiconservative DNA replication.
QCAA Biology · Unit 4 · Genetics and heredity
READY TO TRY IT?

Put the idea to work.

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