Biology Edexcel Topic 3 (Variation and the human genome project)

3.20 to 3.23

What are the two causes of variation within a species?

Genetics, environment

What is genetic varation?

Variations in the genotypes of organisms of the same species happens due to the presence of different alleles, which creates differences in phenotypes

What creates genetic variation in a species?

Spontaneous mutations, sexual reproduction

What is a mutation?

A random change to the base sequence in DNA which results in genetic variants

State the three main types of gene mutation

Insertion, deletion, substitution

How may a neutral gene mutation affect an organism's phenotype?

It does not change the sequence of amino acids so the protein structure and function stay the same and there is no effect on the phenotype

How may a minor gene mutation affect an organism's phenotype?

The mutation may cause a minor change in an organism's phenotype such as a change in eye colour

How may a major gene mutation affect an organism's phenotype?

It may completely change the sequence of amino acids, which may result in a non-functional protein and there would be severe changes to the phenotype

What is environmental variation?

Variations in phenotype that are acquired during the lifespan of an organism due to environmental factors such as diet, lifestyle, climate or exposure to light

What is the human genome project?

A 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 genome

How can the results of the human genome project be applied to medicine?

It enables scientists to understand how lifestyle factors interact with genes which can identify predisposition to disease and possible preventions, disease-causing alleles can be identified more rapidly and the treatments prescribed earlier and scientists can predict an individual's response to certain drugs, so new drugs can be developed which are tailored to a specific allele

What are the drawbacks associated with the discoveries of the human genome project?

Knowledge of predisposition to a disease can be stressful for some people, societal pressure from seeing your genome can influence the decision to have children and there could be discrimination by employers or insurance firms