Edexcel International A Level Biology

Revision Notes

2.12 How Bases Code for a Polypeptide Chain

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Crick's Central Dogma

  • A gene is a sequence of nucleotides that forms part of a DNA molecule (one DNA molecule contains many genes)
  • This sequence of nucleotides (the gene) codes for the production of a specific polypeptide (protein)
  • Protein molecules are made up of a series of amino acids bonded together
  • The shape and behaviour of a protein molecule depends on the exact sequence of these amino acids (the initial sequence of amino acids is known as the primary structure of the protein molecule)
  • The genes in DNA molecules, therefore, control protein structure (and as a result, protein function) as they determine the exact sequence in which the amino acids join together when proteins are synthesised in a cell

From gene to polypeptide

A gene is a sequence of nucleotides that codes for the production of a specific protein molecule (polypeptide)

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Author: Marlene

Marlene graduated from Stellenbosch University, South Africa, in 2002 with a degree in Biodiversity and Ecology. After completing a PGCE (Postgraduate certificate in education) in 2003 she taught high school Biology for over 10 years at various schools across South Africa before returning to Stellenbosch University in 2014 to obtain an Honours degree in Biological Sciences. With over 16 years of teaching experience, of which the past 3 years were spent teaching IGCSE and A level Biology, Marlene is passionate about Biology and making it more approachable to her students.