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Questions and Answers
What condition did Sir Archibald Garrod primarily study that supported his concept of inborn errors of metabolism?
What condition did Sir Archibald Garrod primarily study that supported his concept of inborn errors of metabolism?
- Albinism
- Cystinuria
- Alkaptonuria (correct)
- Pentosuria
What was one of the key observations Garrod made regarding patients with alkaptonuria?
What was one of the key observations Garrod made regarding patients with alkaptonuria?
- They had normal excretion of homogentisic acid.
- They excreted large quantities of uric acid.
- They showed symptoms of albinism.
- They had a familial distribution of the condition. (correct)
What kind of inheritance pattern did William Bateson explain regarding the condition studied by Garrod?
What kind of inheritance pattern did William Bateson explain regarding the condition studied by Garrod?
- X-linked dominant inheritance
- Recessive inheritance (correct)
- Autosomal dominant inheritance
- Mitochondrial inheritance
According to Garrod's concept, diseases of lifelong duration arise due to what?
According to Garrod's concept, diseases of lifelong duration arise due to what?
Garrod attributed the accumulation of homogentisic acid in alkaptonuria to what metabolic failure?
Garrod attributed the accumulation of homogentisic acid in alkaptonuria to what metabolic failure?
What did the confirmation of Garrod's hypothesis regarding alkaptonuria reveal in the 1958 study?
What did the confirmation of Garrod's hypothesis regarding alkaptonuria reveal in the 1958 study?
Which early 20th-century geneticist first applied the term 'gene' to hereditary determinants?
Which early 20th-century geneticist first applied the term 'gene' to hereditary determinants?
Which of Mendel's laws specifically explains the formation of gametes with different combinations of traits?
Which of Mendel's laws specifically explains the formation of gametes with different combinations of traits?
What does Garrod mean by 'diathesis'?
What does Garrod mean by 'diathesis'?
Which statement accurately reflects the concept of chemical individuality?
Which statement accurately reflects the concept of chemical individuality?
How do geneticists view the human population compared to physicians?
How do geneticists view the human population compared to physicians?
What is the significance of the ApoE4 allele?
What is the significance of the ApoE4 allele?
What percentage of the population carries the ApoE2 allele?
What percentage of the population carries the ApoE2 allele?
Why is the ApoE3 allele considered the most common?
Why is the ApoE3 allele considered the most common?
Which of the following best describes individuals with the E4/4 genotype?
Which of the following best describes individuals with the E4/4 genotype?
What are the implications of Garrod's findings on chemical individuality?
What are the implications of Garrod's findings on chemical individuality?
What does the one gene-one enzyme concept state about biochemical reactions?
What does the one gene-one enzyme concept state about biochemical reactions?
Which of the following diseases is associated with a loss-of-function mutation in an enzyme-encoding gene?
Which of the following diseases is associated with a loss-of-function mutation in an enzyme-encoding gene?
Who performed pioneering experiments that linked DNA to heredity?
Who performed pioneering experiments that linked DNA to heredity?
What was the first enzyme defect in a human genetic disease demonstrated in 1948?
What was the first enzyme defect in a human genetic disease demonstrated in 1948?
What was the significance of Garrod's work regarding alkaptonuria?
What was the significance of Garrod's work regarding alkaptonuria?
Which enzyme deficiency is responsible for phenylketonuria (PKU)?
Which enzyme deficiency is responsible for phenylketonuria (PKU)?
What is the implication of Garrod's notion of 'chemical individuality'?
What is the implication of Garrod's notion of 'chemical individuality'?
What does the one gene-one enzyme concept suggest about mutations?
What does the one gene-one enzyme concept suggest about mutations?
What is the frequency threshold for an allele to be considered standard or normal at a genetic locus?
What is the frequency threshold for an allele to be considered standard or normal at a genetic locus?
What defines a polymorphic locus?
What defines a polymorphic locus?
Which genetic variations are linked to the discovery of DNA polymorphism?
Which genetic variations are linked to the discovery of DNA polymorphism?
How much of the human genome is estimated to be polymorphic?
How much of the human genome is estimated to be polymorphic?
What role does most DNA polymorphism play in relation to human phenotypic differences?
What role does most DNA polymorphism play in relation to human phenotypic differences?
What discovery around 1953 significantly advanced the study of human genetics?
What discovery around 1953 significantly advanced the study of human genetics?
What significant development in the 1970s allowed for the preparation of restriction maps?
What significant development in the 1970s allowed for the preparation of restriction maps?
Which phenomena are considered when categorizing genomic polymorphism related to disease susceptibility?
Which phenomena are considered when categorizing genomic polymorphism related to disease susceptibility?
Study Notes
Inborn Errors of Metabolism
- Garrod's studies of alkaptonuria led to the concept of inborn errors of metabolism.
- He observed that patients with alkaptonuria excreted large amounts of homogentisic acid throughout their lives.
- This condition was inherited as a recessive trait.
- Garrod also observed similar phenotypes in albinism, cystinuria, and pentosuria, which led him to propose that certain diseases were caused by a lack or deficiency of an enzyme responsible for a specific metabolic step.
One Gene-One Enzyme Concept
- George Beadle and Edward Tatum developed the one gene-one enzyme concept using experiments with bread mold.
- The concept states that each biochemical reaction is controlled by a single gene.
- Mutation of a single gene affects the ability of the cell to perform a specific chemical reaction.
DNA and Heredity
- Oswald Avery's experiments demonstrated that DNA, not protein, carries hereditary information.
- The first enzyme defect in a human genetic disease, a deficiency of cytochrome-b5 reductase in recessive methemoglobinemia, was identified by Quentin Gibson in 1948.
- Subsequent studies led to the discovery of the genetic basis for several other diseases, including von Gierke disease (glycogen storage disease type I), phenylketonuria (PKU), and others.
Genetic Diversity in Humans
- Garrod recognized the concept of chemical individuality, proposing that differences in metabolism could lead to variations in the chemical makeup of individuals.
- This concept was later explained by the discovery of genetic polymorphism.
- A polymorphic locus is one where the most common allele has a frequency less than 0.99.
- Many genetic loci exhibit polymorphism, leading to variations in human traits and susceptibility to disease.
Recombinant DNA Revolution
- The discovery of DNA structure by Watson and Crick in 1953 paved the way for the recombinant DNA revolution.
- The development of restriction enzymes, cloning techniques, and DNA sequencing methods revolutionized the study of human genetics.
- These advancements allow for the identification and characterization of genes, the discovery of mutations, and the development of new therapies for genetic diseases.
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Description
Explore the groundbreaking concepts of inborn errors of metabolism as introduced by Garrod, along with the one gene-one enzyme theory by Beadle and Tatum. Learn about the pivotal role of DNA in heredity and its implications in various metabolic disorders. This quiz will test your understanding of the relationship between genetics and metabolism.
