Textbook Question
How would the results vary in cross (a) of Problem 32 if genes A and B were linked with no crossing over between them? How would the results of cross (a) vary if genes A and B were linked and 20 map units (mu) apart?
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Ch. 13 - Translation and Proteins
Klug10th EditionEssentials of GeneticsISBN: 9780135588789
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Table of contents
- Ch. 1 - Introduction to Genetics16
- Ch. 2 - Mitosis and Meiosis28
- Ch. 3 - Mendelian Genetics37
- Ch. 4 - Modification of Mendelian Ratios53
- Ch. 5 - Sex Determination and Sex Chromosomes32
- Ch. 6 - Chromosome Mutations: Variation in Number and Arrangement37
- Ch. 7 - Linkage and Chromosome Mapping in Eukaryotes36
- Ch. 8 - Genetic Analysis and Mapping in Bacteria and Bacteriophages24
- Ch. 9 - DNA Structure and Analysis38
- Ch. 10 - DNA Replication29
- Ch. 11 - Chromosome Structure and DNA Sequence Organization22
- Ch. 12 - The Genetic Code and Transcription36
- Ch. 13 - Translation and Proteins27
- Ch. 14 - Gene Mutation, DNA Repair, and Transposition34
- Ch. 15 - Regulation of Gene Expression in Bacteria22
- Ch. 16 - Regulation of Gene Expression in Eukaryotes37
- Ch. 17 - Recombinant DNA Technology27
- Ch. 18 - Genomics, Bioinformatics, and Proteomics30
- Ch. 19 - The Genetics of Cancer21
- Ch. 20 - Quantitative Genetics and Multifactorial Traits37
- Ch. 21 - Population and Evolutionary Genetics45
Chapter 13, Problem 23
Many antibiotics are effective as drugs to fight off bacterial infections because they inhibit protein synthesis in bacterial cells. Using the information provided in the following table that highlights several antibiotics and their mode of action, discuss which phase of translation is inhibited: initiation, elongation, or termination. What other components of the translational machinery could be targeted to inhibit bacterial protein synthesis?
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Review the phases of translation: initiation (assembly of the ribosome on mRNA and start codon recognition), elongation (addition of amino acids to the growing polypeptide chain), and termination (release of the completed polypeptide when a stop codon is reached).
Examine the mode of action of each antibiotic listed in the table to determine which specific step of translation it affects. For example, if an antibiotic prevents the formation of the initiation complex, it inhibits initiation; if it blocks the movement of the ribosome along mRNA or the addition of amino acids, it inhibits elongation; if it interferes with release factors or ribosome disassembly, it inhibits termination.
Identify the molecular targets of these antibiotics, such as the 30S or 50S ribosomal subunits, tRNA binding sites (A, P, or E sites), or factors involved in translation (e.g., initiation factors, elongation factors, or release factors).
Discuss other components of the translational machinery that could be targeted to inhibit bacterial protein synthesis, such as aminoacyl-tRNA synthetases (which charge tRNAs with amino acids), ribosomal RNA, or specific translation factors unique to bacteria.
Summarize how targeting different phases or components of translation can effectively inhibit bacterial protein synthesis and why this specificity is important for antibiotic function.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Phases of Translation
Translation is the process of protein synthesis and occurs in three main phases: initiation, elongation, and termination. Initiation involves assembly of the ribosome on mRNA and the start tRNA, elongation adds amino acids to the growing polypeptide chain, and termination releases the completed protein when a stop codon is reached.
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Translation initiation
Mechanism of Antibiotic Action on Translation
Many antibiotics inhibit bacterial protein synthesis by targeting specific steps in translation. For example, some block initiation by preventing ribosome assembly, others inhibit elongation by interfering with tRNA binding or peptide bond formation, and some affect termination by disrupting release factors. Understanding these mechanisms helps identify which phase is inhibited.
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Components of the Translational Machinery as Drug Targets
The translational machinery includes ribosomal subunits, mRNA, tRNAs, aminoacyl-tRNA synthetases, and various translation factors. Antibiotics can target any of these components to inhibit protein synthesis, such as binding to the 30S or 50S ribosomal subunits, blocking tRNA charging, or interfering with elongation factors, thereby halting bacterial growth.
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Related Practice
Textbook Question
Three independently assorting genes (A, B, and C) are known to control the following biochemical pathway that provides the basis for flower color in a hypothetical plant:
Three homozygous recessive mutations are also known, each of which interrupts a different one of these steps. Determine the phenotypic results in the F1 and F2 generations resulting from the P1 crosses of true-breeding plants listed here:
colorless (aaBBCC) × green (AABBcc)