Sickle Cell Activity: Understanding alleles that are incompletely dominant, looking at the pedigree level and using meiosis.
GenScope File: SickleCell.gs
Open up the Sickle Cell file. Notice
that both Jack and Jill have the sickle cell trait -in other words, they
have one sickle cell allele and one allele for normal hemoglobin beta.
1. You are going to use the cross tool to give Jack & Jill a family. The file is set so that they will have exactly four kids, but since they get their chromosomes randomly from their parents they won't all be the same. Count how many of the kids have normal hemoglobin beta, how many have sickle cell trait, and how many have sickle cell disease. Then enter your data below.
Sickle Cell trait: ________________
Sickle Cell disease: ______________
2. Now try to give Jack and Jill a single baby with normal hemoglobin. You do this just the way you did with dragons. First you get a cell from each of the parents, then you run meiosis on the two cells, look at the chromosomes with the magnifying glass, and pick the gametes you want to fertilize. If you do it just right you'll get a baby that does not carry the sickle cell allele.
When you've got your baby, call your
teacher over and show it off!
You've probably noticed that all of Jack and Jill's kids who have normal
hemoglobin are blue! This is caused by a disease called "methemoglobin."
Methemoglobin is recessive, just as sickle cell is-you get it if you have
two recessive (m) alleles. Can you figure out why all the kids who are
normal for sickle cell have methemoglobin?
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