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12 Cards in this Set
- Front
- Back
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________ is an inherited biochemical variation resulting from a block in a pathway due to genetic deficiency of an enzyme or protein
A. inborn error of metabolism B. structural gene mutation C. regulatory gene mutation |
A. inborn error of metabolism
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True or False:
Most inherited metabolic disease are caused by mutations in genes that encode enzymes. |
True.
Also: - are associated with enzymes that have <10% residual catalytic activity involve a catabolic pathway - exhibit considerable phenotypic variability - are inherited as autosomal recessive traits |
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Though most inborn errors of metabolism are recessive traits, some are indeed dominant. What makes the difference?
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IEM are dominant when the functional proteins are MULTIMERS.
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What is the more common of the two general types of protein mutations:
structural gene mutation or regulatory gene mutation? |
structural gene mutation
like sicklel cell anemia (due to a single point mutation) |
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Which of the following does NOT describe structural gene mutations?
A. The protein is made in reduced quantities, or not at all, or degraded too rapidly B. The altered protein usually has < 10% of its mean normal activity C. The altered protein will differ from the normal protein in kinetics, pH and temperature stability, and electrophoretic stability. |
A. The protein is made in reduced quantities, or not at all, or degraded too rapidly
IS NOT ASSOCIATED WITH STRUCTURAL GENE MUTATIONS, BUT INDEED WITH REGULATORY GENE MUTATIONS. Structural gene mutations are made at normal quantities. |
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Autosomal recessive inborn error of metabolism cystinuria is an example of a:
A. Transport Defect B. Receptor Defect C. Enzyme defect |
A. Transport Defect
Defect is in renal absorption of cystine and the dibasic amino acids which eventually lead to kidney stones |
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Autosomal dominant inborn error of metabolism familial hypercholesterolemia is a
A. Transport Defect B. Receptor Defect C. Enzyme defect |
B. Receptor Defect
Defect in LDL receptor and cholesterol cannot enter cell. Thus feedback mechanism does not work and cholesterol is continuously synthesized in large amounts, and results in hypercholesteremia. |
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PKU is an autosomal recessive inborn error of metabolism that has to do with enzyme defect. The defect is deficiency of ________ which converts phenylalanine to ________ , thus causing phenylalanine to build up toxicly in the cells.
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phenylalanine hydroxylase ; converts phenylalanine to tyrosine
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Why do individuals with PKU have a fair complexion and lack or have super low levels of dopamine and epinephrine?
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Deficiency of phenylalanine hydroxylase causes deficiency in tyrosine which is a precursor to melanin and the neurotransmitters dopamine and serotonin.
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Regarding treatment of inborn errors, give examples of each:
A. Treatment at the Level of Clinical Phenotype B. Treatment at the Metabolite Level C. Treatment at the Level of Dysfunctional Protein |
A. patient education, pharmacologic treatment, surgical intervention
B. Substrate restriction (ex. for PKU, restrict Phe in diet, for galactosemia, eliminate galactose from diet.) Metabolic inhibitors (ex. statins for familial hypercholetseremia) C. Activation with Vitamin Cofactor, protein replacement/administration therapies, organ replacement |
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Which of the following inborn errors of metabolism are NOT matched with their generalized metabolic pathway?
A. Receptor defect = Familial Hypercholesteremia B. Too much substrate leading to interference with normal cell function = Cystinuria C. Too much substrate -> toxicity = PKU D. Too little product = PKU |
B. Too much substrate leading to interference with normal cell function = Cystinuria is FALSE because this describes Alkaptonuria, not Cystinuria which is a transport defect.
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Which of the following is NOT a characteristic of PKU regarding generalized metabolic pathway?
A. Too little product B. Too much substrate--> toxicity C. Too much substrate ---> interferes with normal cell function D. Too much minor metabolites |
C. Too much substrate ---> interferes with normal cell function
That actually is a characteristic of Alkaptonuria |
