ASBiologyCambridge (CIE)Revision Notes6. Nucleic Acids & Protein SynthesisProtein SynthesisFrom Gene to Polypeptide

From Gene to Polypeptide (Cambridge (CIE) AS Biology): Revision Note

Exam code: 9700

Marlene

Written by: Marlene

Reviewed by: Alistair Marjot

Updated on

From gene to polypeptide

  • A gene is a sequence of nucleotides that forms part of a DNA molecule

    • One DNA molecule contains many genes

  • This sequence of nucleotide bases (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 depend on the exact sequence of these amino acids

    • This means that the genes in DNA molecules control protein structure (and as a result, protein function)

    • This is because genes determine the exact sequence in which the amino acids join together when proteins are synthesised in a cell

Diagram showing a cell with a nucleus containing chromosomes. DNA is depicted, with genes coded as nucleotide sequences, leading to protein formation.
A gene is a sequence of nucleotides that codes for the production of a specific protein molecule (polypeptide)

Examiner Tips and Tricks

One gene codes for one mRNA molecule, which codes for one polypeptide.

Remember—each chromosome in a human cell nucleus contains one very long DNA molecule.

This DNA molecule is made up of thousands of specific nucleotide sequences called genes that code for specific proteins.

Even though these genes are all found within the same DNA molecule and are therefore all linked up, each individual gene has a specific start and stop point.

This ensures that the DNA is read correctly and that the correct protein molecules are produced that are required by the cell to function properly.

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    Author
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    Marlene

    Author: Marlene

    Expertise: Biology Content Creator

    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.

    Alistair Marjot

    Reviewer: Alistair Marjot

    Expertise: Environmental Systems and Societies & Biology Content Creator

    Alistair graduated from Oxford University with a degree in Biological Sciences. He has taught GCSE/IGCSE Biology, as well as Biology and Environmental Systems & Societies for the International Baccalaureate Diploma Programme. While teaching in Oxford, Alistair completed his MA Education as Head of Department for Environmental Systems & Societies. Alistair has continued to pursue his interests in ecology and environmental science, recently gaining an MSc in Wildlife Biology & Conservation with Edinburgh Napier University.