Textbook Question
Define and compare the four levels of protein organization.
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 23
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.
Verified step by step guidance1
Step 1: Identify the codons for the normal and substituted amino acids using the standard genetic code table. Each amino acid is encoded by one or more codons (triplets of nucleotides).
Step 2: For each hemoglobin variant, write down the codon(s) that could encode the normal amino acid and the codon(s) that could encode the substituted amino acid.
Step 3: Compare the codons for the normal and substituted amino acids to determine if the substitution can be caused by a single-nucleotide change. This means checking if changing one nucleotide in the normal codon can produce a codon for the substituted amino acid.
Step 4: Count how many of the amino acid substitutions in the table can be explained by a single-nucleotide change in the codon.
Step 5: Summarize your findings by stating the total number of substitutions that can occur due to a single-nucleotide change, based on your codon comparisons.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Genetic Code and Codon Table
The genetic code consists of nucleotide triplets called codons, each specifying an amino acid. Understanding the codon table is essential to determine how a single-nucleotide change (point mutation) can alter a codon to code for a different amino acid, leading to amino acid substitutions in proteins.
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The Genetic Code
Missense Mutations and Single-Nucleotide Changes
Missense mutations are point mutations where a single nucleotide change results in a codon that codes for a different amino acid. Identifying whether an amino acid substitution can arise from a single-nucleotide change requires comparing codons of the original and substituted amino acids.
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Hemoglobin Structure and Variants
Hemoglobin is composed of α and β chains, each with specific amino acid sequences. Variants arise from amino acid substitutions in these chains, which can affect function. Understanding the location and nature of these substitutions helps relate genetic mutations to protein changes.
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Related Practice
Textbook Question
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.
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Textbook Question
What are the two common types of protein secondary structure, and how do they differ?
Textbook Question
Contrast the contributions of Pauling and Ingram to our understanding of the genetic basis for sickle-cell anemia.
Textbook Question
How do covalent disulfide bonds, hydrogen bonds with water, and hydrophobic interactions all contribute to a protein's tertiary structure?
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?