DNA Structure, the Genome and Genes — AQA GCSE Biology
DNA carries the genetic instructions for building and running an organism.
DNA and chromosomes
- The genetic material is DNA — a polymer made of two strands forming a double helix.
- DNA is contained in structures called chromosomes, found in the nucleus.
- A gene is a small section of DNA that codes for a particular sequence of amino acids, which makes a specific protein.
The genome
The genome of an organism is its entire genetic material. Understanding the human genome is important because it allows scientists to:
- search for genes linked to diseases,
- understand and treat inherited disorders, and
- trace human migration and ancestry.
DNA structure (Higher Tier / Separate)
- DNA is made of units called nucleotides, each containing a sugar, a phosphate and one of four bases (A, T, C, G).
- The bases pair up: A with T, and C with G (complementary base pairing).
- The order of the bases is the genetic code that determines which amino acids are joined together to make a protein.
Exam tips
- DNA is a polymer in a double helix, found in chromosomes.
- A gene codes for a sequence of amino acids (a protein).
- Define the genome as the entire genetic material; know why studying it is useful.
- Learn the base pairs: A–T and C–G.