This key facts covers Structure of DNA within DNA Genome for GCSE Biology. DNA structure, function, and the human genome It is section 2 of 13 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 2 of 13
Practice
25 questions
Recall
25 flashcards
Structure of DNA
- DNA is a double helix — two strands twisted together
- Made of nucleotides — each has a sugar, phosphate, and base
- Four bases: Adenine (A), Thymine (T), Cytosine (C), Guanine (G)
- Complementary base pairing: A-T and C-G always pair together
- The order of bases is the genetic code — it determines which proteins are made
DNA is your body's recipe book. The genome is the whole book. Chromosomes are chapters. Genes are individual recipes. The bases (A, T, C, G) are the letters that spell out each recipe. Different recipes (genes) make different proteins!
Just like English uses 26 letters to write every book ever written, DNA uses only 4 "letters" (A, T, C, G) to code for every living thing! The order of letters creates meaning — "CAT" is different from "ACT".