Textbook Question
Several lines of experimental evidence pointed to a triplet genetic code. Identify three pieces of information that supported the triplet hypothesis of genetic code structure.
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Ch. 9 - The Molecular Biology of Translation
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172
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Table of contents
- Ch. 1 - The Molecular Basis of Heredity, Variation, and Evolution64
- Ch. 2 - Transmission Genetics144
- Ch. 3 - Cell Division and Chromosome Heredity81
- Ch. 4 - Gene Interaction87
- Ch. 5 - Genetic Linkage and Mapping in Eukaryotes103
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages73
- Ch. 7 - DNA Structure and Replication71
- Ch. 8 - Molecular Biology of Transcription and RNA Processing79
- Ch. 9 - The Molecular Biology of Translation110
- Ch. 10 - Eukaryotic Chromosome Abnormalities and Molecular Organization100
- Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination86
- Ch. 12 - Regulation of Gene Expression in Bacteria and Bacteriophage90
- Ch. 13 - Regulation of Gene Expression in Eukaryotes38
- Ch. 14 - Analysis of Gene Function via Forward Genetics and Reverse Genetics72
- Ch. 15 - Recombinant DNA Technology and Its Applications69
- Ch. 16 - Genomics: Genetics from a Whole-Genome Perspective49
- Ch. 17 - Organelle Inheritance and the Evolution of Organelle Genomes27
- Ch. 18 - Developmental Genetics43
- Ch. 19 - Genetic Analysis of Quantitative Traits66
- Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels105
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
Chapter 9, Problem 2c
In the experiments that deciphered the genetic code, many different synthetic mRNA sequences were tested.
What result was obtained for synthetic mRNAs containing AG repeats, that is, AGAGAGAG...?
Verified step by step guidance1
Understand the context: The problem involves deciphering the genetic code using synthetic mRNA sequences. The sequence provided, AGAGAGAG..., is a repeating dinucleotide sequence. The goal is to determine the result of translating this sequence into a polypeptide chain.
Recall the codon structure: Each codon consists of three nucleotides, and the genetic code translates these codons into specific amino acids. For the sequence AGAGAGAG..., the codons will be read in overlapping triplets as AGA, GAG, AGA, and so on.
Determine the amino acids encoded: Use the genetic code table to identify the amino acids corresponding to the codons. For example, AG(A) codes for one amino acid, and GA(G) codes for another. Identify these amino acids from the table.
Consider the repeating pattern: Since the sequence is repetitive, the resulting polypeptide will also have a repeating pattern of amino acids. Analyze how the sequence AGAGAGAG... translates into a repeating sequence of amino acids.
Summarize the result: The experiment with AG repeats would produce a polypeptide with a repeating pattern of two amino acids, corresponding to the codons AG(A) and GA(G). This demonstrates how synthetic mRNA sequences can be used to decipher the genetic code.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Genetic Code
The genetic code is a set of rules that defines how the sequence of nucleotides in mRNA is translated into amino acids, the building blocks of proteins. It consists of codons, which are triplets of nucleotides, each corresponding to a specific amino acid or a stop signal during protein synthesis.
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The Genetic Code
mRNA and Translation
Messenger RNA (mRNA) is a type of RNA that carries genetic information from DNA to the ribosome, where proteins are synthesized. During translation, ribosomes read the mRNA sequence in codons, facilitating the assembly of amino acids into polypeptides based on the genetic instructions.
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Repetitive Sequences and Codon Bias
Repetitive sequences, such as AG repeats, can influence the translation process due to codon bias, where certain codons are preferred over others in different organisms. This can affect the efficiency and accuracy of protein synthesis, potentially leading to variations in the resulting polypeptide chains.
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Related Practice
Textbook Question
Homocystinuria is a rare autosomal recessive condition on the RUSP list of conditions screened by newborn genetic testing. The condition results from a mutation that blocks the degradation of the amino acid methionine. The absence of a critical enzyme causes the buildup of the compound homocysteine, which is one of the intermediate compounds in the methionine breakdown pathway. Homocystinuria causes mental impairment, heart problems, seizures, eye abnormalities, and a number of other symptoms that shorten life if not treated. The condition is treated by a specialized diet that is low in methionine and by the ingestion of several supplements.
The low-methionine diet must be maintained throughout life to manage homocystinuria. Why do you think this is the case?
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Textbook Question
Outline the events that occur during initiation of translation in E. coli.
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Textbook Question
In the experiments that deciphered the genetic code, many different synthetic mRNA sequences were tested.
Describe how the codon for phenylalanine was identified.
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Textbook Question
In the experiments that deciphered the genetic code, many different synthetic mRNA sequences were tested.
Predict the results of experiments examining GCUA repeats.
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Textbook Question
In the experiments that deciphered the genetic code, many different synthetic mRNA sequences were tested.
What was the result of studies of synthetic mRNAs composed exclusively of cytosine?
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