Questions and Answers
Compare sickle cell disease and malaria.
Sickle cell disease is inherited, while malaria is an infectious disease, and both can cause life-threatening conditions.
What did Dr. Tony Allison hypothesize about sickle cell disease and malaria?
He hypothesized that there was a connection between malaria and sickle cell disease.
How did Dr. Allison test his hypothesis about sickle cell disease being connected to malaria?
He expanded his study area beyond Kenya, evaluated blood samples for malaria parasites, and gathered samples from over 5,000 children in East Africa.
If a person has two normal copies of the hemoglobin allele, which statements are true? (Select all that apply)
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What reason is given for why a potentially deadly, inherited disease like sickle cell disease is found at high frequencies?
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How does Dr. Allison's work provide an example of natural selection in humans?
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Predict what will happen to the frequency of the sickle cell allele in areas where malaria has been eradicated.
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Study Notes
Sickle Cell Disease and Malaria
- Sickle cell disease is inherited, while malaria is an infectious disease; both can lead to life-threatening conditions.
- Individuals with a single sickle cell allele experience protection from malaria without having the disease itself.
Dr. Tony Allison's Research
- In 1949, Dr. Allison observed a higher prevalence of the sickle cell allele in coastal Kenya and around Lake Victoria compared to the highlands.
- He hypothesized a link between malaria and sickle cell disease, predicting that areas with high malaria prevalence would also show high frequencies of sickle cell disease.
Testing the Hypothesis
- Dr. Allison expanded his research across East Africa and collected blood samples from over 5,000 children.
- His study involved evaluating blood for malaria parasites and sickle cell presence, revealing that children with the sickle cell trait had lower malaria parasite counts.
Genetics of Sickle Cell Alleles
- Individuals with two normal hemoglobin alleles are homozygous and particularly susceptible to malaria.
- Homozygous individuals with normal hemoglobin alleles are more vulnerable to malaria compared to those carrying sickle cell alleles.
Frequency of Sickle Cell Disease
- In some populations, sickle cell disease occurs in 1 in 500 people.
- The maintenance of the sickle cell allele in the population is linked to the protective advantage against malaria conferred by possessing one sickle cell allele.
Natural Selection Observations
- Natural selection favors different traits based on environmental factors; in malaria-endemic areas, individuals with one sickle cell allele reproduce more successfully.
- Conversely, in regions without malaria, individuals with two sickle cell alleles have reproductive disadvantages, leading to decreased frequency of the allele.
Future Predictions
- The frequency of the sickle cell allele is expected to decline in areas where malaria has been eradicated.
- Without malaria, the selective pressure that maintains the sickle cell allele diminishes, leading to a probable decrease in its prevalence.
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Description
Explore the vital connections between sickle cell disease and malaria through these informative flashcards. Learn about the genetic aspects of sickle cell disease, its relation to malaria, and historical observations that shed light on these conditions.
