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Hemoglobin and Porphyrins Objectives

Hemoglobin and porphyrins objectives 4 describe the

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Hemoglobin and Porphyrins – Objectives 4. Describe the general structures of hemoglobin chains: primary, secondary, tertiary and quarternary. Primary: amino acids present and their sequence Secondary: 3D arrangement of amino acids in chain –regions of the amino acids may form helixes or pleated structures Tertiary: larger folded superimposed; it represents the position taken by each chain in 3D space Quaternary: represents the relationship of 4 subunits to one another; points of contact – mutations here can affect oxygen affinity of molecule 5. Explain the difference between Hemoglobinopathies and Thalassemias. Hemoglobinopathies involve defects in Hg structure; Thalassemias involve defects in the rate of production of Hg 6. Explain the effects of lead on heme synthesis—list the tests that would be affected by lead poisoning as discussed in lecture. Lead – inhibits enzyme PBG synthase in heme synthesis and the incorporation of iron into heme– inc. copro. in urine, inc. ZPP, inc. ALA----causes a secondary porphyria/ an acquired porphyria 7. Describe the following characteristics of sickle cell: hemoglobin affected/type of defect, population affected, affect on rbcs, symptoms as discussed in lecture. Hemoglobin affect: Hg S Type of Defect: amino acid defect in hg S at the 6 th position on th beta chain where glutamic acid is substituted by valine giving the hg a less negative charge than hg A; individuals either have sickle cell trait --- some protection from parasitic infections like plasmodium falciparum (Hb AS, the heterozygous state) or the sickle cell disease (HbSS, the homozygous state) Population affected: 1 in 500 infants; Black Africans and African Americans have the highest incidence; it is also found in Mediterranean countries such as Greece, Italy, and Israel, as well as in Saudi Arabia and India Effect on RBCs: Crescent shaped rbcs – cell membranes damaged – phagocytized – leads to anemia Symptoms: Creates blockages and Tissue Hypoxia – extreme pain and tissue death; autosplenectomy 8. Explain the difference between alpha and beta thalassemia; describe the most clinically significant forms of each. (Thalassemias are diseases where a defect causes reduced synthesis of 1 or more of the hemoglobin chains----defects in the rate of production of Hg, but the chains are
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Hemoglobin and Porphyrins – Objectives structurally normal; the 2 most common types are alpha and beta thalassemia which result from defects in production of either the alpha or beta chain; causes RBCs to be small, hypochromic, and sometimes deformed; it’s an autosomal dominant disorder w/ heterogeneous expression of the disease; the prevalence of the thalassemia gene has been attributed to the protection it offers against falciparum malaria; the heterogeneous state
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