Lesson summary for:
The Meaning of Genetic Variation
Students investigate variation in the beta globin gene by identifying base
changes that do and do not alter function, and by using several internet-based resources to consider the significance in different environments of the base change associated with sickle cell disease.
National Institutes of Health
two 50 minute periods
This activity is the second in a series entitled Human
Genetic Variation. We also recommend the introductory activity in this module: Alike but Not the Same. Before beginning this activity, students should understand basic Mendelian patterns of inheritance, especially autosomal-recessive inheritance; the basic structure of DNA; the transcription of DNA to messenger RNA; and the translation of messenger RNA to protein. This activity largely focuses on variation but could easily be extended or modified to emphasize variation's role in evolution to a greater degree.
- Evolution results from selection acting upon genetic variation within a population.
- Mutations are random.
- Traits that confer an advantage may persist in the population and are called adaptations.
- Inherited characteristics affect the likelihood of an organism's survival and reproduction.
- Depending on environmental conditions, inherited characteristics may be advantageous, neutral, or detrimental.
- Natural selection acts on phenotype as an expression of genotype.
- There is variation within a population.
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