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Unformatted text preview: Chapter 10 From Proteins to Phenotypes
Chapter 10 Protein Function What do proteins do for us? Some important functions: Structure Enzymes Body Defense Hormones Transport DNA replication and gene expression Enzymes Substrate = Product = Metabolism = Enzymes and Metabolic Pathways Fig. 10.2 Metabolic Pathways Fig. 10.3 Phenylketonuria (PKU) Cause: mutation in phenylalanine hydrolase (PAH) gene phenylalanine Result: unable to process amino acid Leads to: toxic levels of phenylalanine Phenylketonuria (PKU) Affects 1/12,000 newborns Can lead to: brain damage, mental Treatment low phenylalanine diet retardation, seizures, limited pigmentation All newborns screened for PKU Testing Newborns What about the cost? too expensive to test or too expensive not to test?
Fig. 10.5 Mutations In Carbohydrate Metabolism Galactosemia in ability to break down galactose (sugar in milk) Lactose intolerance Galactosemia Autosomal recessive multiple alleles Causes dehydration, loss of appetite jaundice, cataracts, and mental retardation Galactosemia
Treatment Diet of lactose and galactose free foods Some impaired motor skills even with treatment Fig. 10.7 Lactose Intolerance
Controlled by lactase Lactase activity Symptoms? declines with age Frequency varies between populations Which ones? Fig. 10.7 Diseases Receptor Protein Mutations Diabetes insipidus X linked recessive Can't concentrate urine Androgen insensitivity X linked recessive Males have female phenotype Familial Hypercholesterolemia Autosomal dominant High cholesterol Defects in Transport Proteins Change structure of hemoglobin Where do we find this protein? What does it do? Defects in Transport Proteins Fig. 10.9 Defects in Transport Proteins Hemoglobin genes chromosomes 16 & 11 Sickle cell anemia Thalasemia Sickle Cell Anemia Autosomal recessive Symptoms Mutation in the betaglobin gene Changes shape of Hb and red blood cells (RBC) http://www.pubinfo.vcu.edu/secretsofthesequence/download.asp?id =24&vtype=mpeg Normal Hemoglobin Sickle Cell Hemoglobin
Fig 10.14 Fig. 10.14 Thalassemia Disorders Imbalance in the amounts of alpha and beta globins Who most commonly gets this? Two types Alpha thalassemia Beta thalassemia Thalassemia Fig. 10.15 Fig. 10.15 Untreated sickle cell anemia = fatal Treatment of Hemoglobin Disorders Treatment certain anticancer drugs Hydroxyurea: turns off cell division Increses fetal Hb Decreases sickled red blood cells Patterns of Globin Gene Expression Change with Age
Fig 10.16 Fig. 10.16 Differences in Phenotype Ability to taste PTC (phenylthiocarbamide) Similar compound in bitter foods: kale and brussel sprouts Ability to smell Genotype May Affect the Ability to Smell Fig. 10.18 Pharmacogenetics Pharmacogenetics = Differences in metabolism Drug resistances Side effects Cancer Drugs and Genes Malaria Drugs and Fava beans Have similar compounds In certain genotypes causes hemolytic anemia Linked to mutation in G6PD gene Ecogenetics Ecogenetics = 500,000 + chemicals are used in manufacturing and agriculture Only a few tested for toxicity Some due to genotype Variation in individual sensitivity ...
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