Textbook Question
Using sickle-cell anemia as an example, describe what is meant by a molecular or genetic disease. What are the similarities and dissimilarities between this type of a disorder and a disease caused by an invading microorganism?
Ch. 14 - Translation and Proteins
Klug12th EditionConcepts of Genetics ISBN: 9780135564776
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Table of contents
- Ch. 1 - Introduction to Genetics17
- Ch. 2 - Mitosis and Meiosis36
- Ch. 3 - Mendelian Genetics51
- Ch. 4 - Extensions of Mendelian Genetics74
- Ch. 5 - Chromosome Mapping in Eukaryotes51
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages46
- Ch. 7 - Sex Determination and Sex Chromosomes33
- Ch. 8 - Chromosome Mutations: Variation in Number and Arrangement40
- Ch. 9 - Extranuclear Inheritance31
- Ch. 10 - DNA Structure and Analysis43
- Ch. 11 - DNA Replication and Recombination44
- Ch. 12 - DNA Organization in Chromosomes30
- Ch. 13 - The Genetic Code and Transcription54
- Ch. 14 - Translation and Proteins47
- Ch. 15 - Gene Mutation, DNA Repair, and Transposition41
- Ch. 16 - Regulation of Gene Expression in Bacteria29
- Ch. 17 - Transcriptional Regulation in Eukaryotes41
- Ch. 18 - Post-transcriptional Regulation in Eukaryotes33
- Ch. 19 - Epigenetics33
- Ch. 20 - Recombinant DNA Technology44
- Ch. 21 - Genomic Analysis36
- Ch. 22 - Applications of Genetic Engineering and Biotechnology36
- Ch. 23 - Developmental Genetics37
- Ch. 24 - Cancer Genetics34
- Ch. 25 - Quantitative Genetics and Multifactorial Traits54
- Ch. 26 - Population and Evolutionary Genetics45
Chapter 14, Problem 22
HbS results in anemia and resistance to malaria, whereas in those with HbA, the parasite Plasmodium falciparum is able to invade red blood cells and cause malaria. Predict whether those with HbC are likely to be anemic and whether they would be resistant to malaria.
Verified step by step guidance1
Understand the genetic basis of the problem: HbS, HbA, and HbC are alleles of the hemoglobin gene. HbS is associated with sickle cell anemia and malaria resistance, while HbA is the normal allele that allows susceptibility to malaria. HbC is another variant of the hemoglobin gene, and its effects need to be analyzed in this context.
Review the molecular and physiological effects of HbC: Research has shown that individuals with the HbC allele produce hemoglobin with a slightly altered structure. This alteration does not cause sickling of red blood cells like HbS, but it may affect the ability of Plasmodium falciparum to invade red blood cells.
Analyze the likelihood of anemia in individuals with HbC: Since HbC does not cause sickling of red blood cells, individuals with the HbC allele are less likely to experience the severe anemia associated with HbS. However, some mild effects on red blood cell function may still occur.
Evaluate malaria resistance in individuals with HbC: Studies suggest that the HbC allele provides some level of resistance to malaria, though not as strong as the resistance seen in individuals with the HbS allele. This resistance is likely due to the altered red blood cell environment, which makes it harder for Plasmodium falciparum to thrive.
Conclude the predictions: Based on the above analysis, individuals with HbC are less likely to be anemic compared to those with HbS, and they are likely to have some resistance to malaria, though not as strong as that conferred by HbS.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Sickle Cell Trait and Malaria Resistance
Individuals with the HbS variant of hemoglobin have a mutation that causes sickle-shaped red blood cells, which are less hospitable to the malaria parasite Plasmodium falciparum. This trait provides a selective advantage in malaria-endemic regions, as it reduces the severity of malaria infections, leading to increased survival rates among carriers.
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Traits and Variance
Hemoglobin Variants
Hemoglobin variants, such as HbA, HbS, and HbC, are different forms of hemoglobin that arise from mutations in the HBB gene. HbA is the normal form, while HbC is another variant that can affect red blood cell shape and function, potentially influencing susceptibility to anemia and malaria.
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Anemia and Its Causes
Anemia is a condition characterized by a deficiency in red blood cells or hemoglobin, leading to reduced oxygen transport in the body. It can result from various factors, including genetic disorders like sickle cell disease or HbC, nutritional deficiencies, or chronic diseases, impacting overall health and resistance to infections.
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Related Practice
Textbook Question
Contrast the contributions of Pauling and Ingram to our understanding of the genetic basis for sickle-cell anemia.
Textbook Question
Hemoglobins from two individuals are compared by electrophoresis and by fingerprinting. Electrophoresis reveals no difference in migration, but fingerprinting shows an amino acid difference. How is this possible?
Textbook Question
Several amino acid substitutions in the α and β chains of human hemoglobin are shown in the following table.
Using the code table, determine how many of them can occur as a result of a single-nucleotide change.
Textbook Question
Define and compare the four levels of protein organization.
Textbook Question
What are the two common types of protein secondary structure, and how do they differ?