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Evolution through mutation? Sickle-cell anemia sickle-cell anemia is caused by a single amino acid mutation in the hemoglobin gene; evolutionists claim this is an example of evolution Hemoglobin: protein in red blood cells that carries oxygen throughout the body http://www.pbs.org/wgbh/evolution/library/01/2/l_012_02.html Children with “sickle cell trait (HbAS) [have] a slight survival advantage to malaria over those without the mutation” (HbAA) (CDC) However, children with sickle cell disease (HbSS) have the lowest chance of survival, because sickle cell anemia is often deadly. What is Malaria? • http://www.malariasite.com/malaria/LifeCycle.htm http://www.nytimes.com/2011/11/15/health/biochemistry-scientists-decode-the-protective-element-sickle-cell-anemia-offers-against-malaria.html What is Sickle Cell Anemia? - molecules of sickle-cell hemoglobin stick to one another, forming rigid rods. - sickled cells do not carry oxygen well and tend to clog capillaries, leading to the blood supply being cut of organs like the brain and heart. - slight exertion can lead to heart attack or stroke. http://www.nature.com/scitable/topicpage/genetic-mutation-441 Is Sickle-Cell really a good example for Evolutionists to use? • Only one base (adenine to thymine) changes in sickle cell anemia; the beta globin portion of hemoglobin alone has 147 amino acids, coded for by 147 codons, which have 3 bases each. So its about 1/141 base pairs. • Sickle cell anemia is not really a solution to malaria, as those who get both genes (25%) are more likely to die, and those who get one gene (50%) are only slightly resistant to malaria. Sickle Cell Inheritance Look at the picture. What type of trait is sickle cell anemia? Sickle cell anemia is a dominant-recessive trait Is sickle cell anemia dominant or recessive? Recessive. The child has to receive to sickle Cell from both parents. • How many codons are there in hemoglobin? Hemoglobin has 4 subunits, two called betaglobin, and the other two alpha-globin. Betaglobin is a single chain of 147 amino acids, which means just the beta-globin portion of hemoglobin has 147 codons. What happens if there is mutation in another codon of beta-hemoglobin? – Some mutations have no effect: GluB26 Lys – Some increase or reduce oxygen holding abilities: AspB99 His & AsnB102 Thr – More than 250 mutations in the beta-globin portion cause beta thalassemia, which disrupts red blood cell development, preventing these cells from carrying sufficient oxygen, leading to poor growth, organ damage, etc… – Methemoglobinemia, beta-globin type • http://ghr.nlm.nih.gov/gene/HBB