Explore how a single DNA mutation affects red blood cells, blood flow, and malaria resistance. This interactive simulation lets you control genetics and observe the consequences in real time.
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Red Blood Cells & Hemoglobin
Red blood cells carry oxygen using a protein called hemoglobin. Normal hemoglobin (HbA) keeps cells flexible and disc-shaped, allowing smooth flow through blood vessels. The hemoglobin beta gene (HBB) is located on chromosome 11.
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The Sickle Cell Mutation
A single nucleotide change in codon 6 of the HBB gene changes the DNA template strand from CTC → CAC. This means the mRNA changes from GAG → GUG, switching the amino acid from glutamic acid to valine. This produces abnormal hemoglobin (HbS) that causes red blood cells to become rigid, sticky crescents.
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Genotypes & Their Effects
HbA/HbA — Normal cells, healthy blood flow. HbA/HbS — Carrier with mostly normal cells (sickle cell trait). HbS/HbS — Sickle cell disease: cells clump and block vessels, causing pain and organ damage.
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Malaria & Sickle Cell Protection
The malaria parasite Plasmodium invades normal red blood cells. Carriers (HbA/HbS) are protected because the parasite cannot thrive in their cells. This heterozygote advantage explains why the sickle allele persists in malaria-endemic regions.