I understand mostly about how traits are passed through parents to children, but how does the exact mutation for sickle cell get passed down onto a child? I’m so confused.
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Sickle trait is a mutation in the beta chain of hemoglobin, the protein that moves oxygen in your blood cells. Every protein is coded for by a sequence of DNA, which is transcribed to RNA then translated to a protein. Each person has two copies of every gene (thousands of genes) and puts one copy or the other of each gene into an egg cell or sperm cell. When an egg is fertilized by a sperm, the offspring have two copies of every gene. One they got from mom and one from dad. It’s a back up system so that if you have a mutation, the other copy of the gene probably works, so at least one copy gives you the proteins you need.
In some regions having a copy of the mutated sickle gene from one parent and a normal gene from the other parent let’s you have good resistance to malaria, but fairly normal blood. Half the proteins that the normal gene makes is normal, but the other half is mutated. So people with one of each are at an advantage. But if a child inherits a mutated copy from mom and a mutated copy from dad, the only hemoglobin proteins they make don’t fold up correctly and stick together, making the blood cells stretch out and look like sickles. These don’t get oxygen to all of the body and clog up blood vessels, so it’s a pretty harmful disease.
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