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14 Cards in this Set
- Front
- Back
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Describe the mutation that causes sickle cell anemia
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Autosomal recessive, defect in HBB (beta chain of hemoglobin). Muted amino acid 6 (GLU to VAL)- need to have both genes to have sickle cell. One bad copy = good against malaria.
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Name some symptoms of sickle cell:
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jaundice, delayed growth, retina damage, infections/strikes, chest pain, fatigue, joint pain.
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This mutation in the 6th amino acid - what is its functional affect?
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replacing a negatively charged residue with a hydrophobic one - now, DEOXYGENATED HbS (Hb sickle) can aggregate/polymerize with other hemoglobin molecules = sickle shape.
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What chemical can be used in the treatment of sickle cell disease? Other possible treatments?
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hydroxyurea - this encourages the growth of HbF (fetal hemoglobin). Blood/bone marrow transfusions, prophylactic antibiotics,
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What kind of alpha chain subtypes are there?
What kind of beta chain subtypes are there? |
alpha: alpha and zeta chains
beta: beta, gamma, delta, epsilon. |
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In the adult, what kinds of hemoglobin is present?
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A - 95%, mix of alpha and beta
A2 - 3%, mix of alpha and delta |
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In the fetal stage, what kinds of globin chains are combined?
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Alpha and gamma
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In the embryonic stage, what kinds of glovin chains are combined?
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zeta and epsilon.
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on what chromosome do you find alpha globin?
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clustered on c/some 16
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on what chromosome do you find beta globin?
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clustered on c/some 11
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What is a thalassemia?
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deficiencies of alpha or beta globin chains, resulting from all sorts of mutations.
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What kind of thalassemia is caused by a mutation in the coding region of beta-globin?
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Beta-zero (B-0) mutations in the intron/exon junctions to block splicing, nonsense mutations, frame shifts. severe, non-functional beta globin.
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What are other possible mutations in thalassemia?
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mutations in control regions - get some level of expression. These are B+ thalasemias. Some are in close promoters, some are up to 50kb away in enhancer sequences.
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What is the locus control region?
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LCR is where B+ mutations can happen - essential for high level tarscription. Good candidates for gene therapy.
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