Variation and the Human Genome Project

• Genetic variation

  • Variation in the genotypes of organisms of the same species due to the presence of different alleles

  • Creates differences in phenotypes
• Mutation


  A random change in the base sequence of DNA which results in genetic variants
• Three types of gene mutation

  • Insertion

  • Deletion

  • Substitution
• How may a gene mutation affect an organism’s phenotype?

  • Neutral mutation -> does not change the sequence of amino acids. Protein structure and function remain the same. No effect on phenotype

  • Mutation may cause a minor change in an organism’s phenotype e.g. change in eye colour

  • Mutation may completely change the sequence of amino acids. This may result in a non-functional protein. Severe changes to phenotype
• Environmental variation

  • Variations in phenotype that are acquired during the lifespan of an organism

  • Due to environmental factors e.g. diet, lifestyle, climate, exposure to light etc
• Human Genome Project

  • Scientific research project involving thousands of scientists across the globe which successfully mapped the entire human genome

  • Scientists now aim to identify the function of every gene in the human genome
• How can the results of the Human Genome Project be applied to medicine?

  • Enables scientists to understand how lifestyle factors interact with genes - identifying predisposition to disease and possible preventions

  • Disease-causing alleles identified more rapidly and the appropriate treatments prescribed earlier on

  • Scientists can predict an individual’s response to certain drugs. New drugs can be developed which are tailored to a specific allele
• Drawbacks associated with the discoveries of the Human Genome Project?

  • Knowledge of predisposition to a disease can be stressful

  • Societal pressure influencing the decision to have children

  • Discrimination by employers