Textbook Question
An experiment by Khorana and his colleagues translated a synthetic mRNA containing repeats of the trinucelotide UUG.
How many reading frames are possible in this mRNA?
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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 25b
An experiment by Khorana and his colleagues translated a synthetic mRNA containing repeats of the trinucelotide UUG.
What is the result obtained from each reading frame?
Verified step by step guidance1
Understand the problem: The synthetic mRNA contains repeats of the trinucleotide UUG. Translation occurs in three possible reading frames, and each frame determines the sequence of codons that are read to produce amino acids.
Step 1: Write out the sequence of the synthetic mRNA. Since it contains repeats of UUG, the sequence can be represented as UUGUUGUUGUUG... (repeating indefinitely).
Step 2: Identify the codons in the first reading frame. Start reading from the first nucleotide (U) and group the sequence into codons of three nucleotides each: UUG, UUG, UUG, etc.
Step 3: Identify the codons in the second reading frame. Start reading from the second nucleotide (U) and group the sequence into codons of three nucleotides each: UGU, UGU, UGU, etc.
Step 4: Identify the codons in the third reading frame. Start reading from the third nucleotide (G) and group the sequence into codons of three nucleotides each: GUU, GUU, GUU, etc.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
mRNA Translation
mRNA translation is the process by which ribosomes synthesize proteins based on the sequence of nucleotides in messenger RNA (mRNA). Each set of three nucleotides, known as a codon, corresponds to a specific amino acid. Understanding this process is crucial for interpreting the results of experiments involving synthetic mRNA, as it directly affects the resulting protein structure and function.
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Translation initiation
Reading Frames
A reading frame refers to the way nucleotides in mRNA are grouped into codons during translation. There are three possible reading frames for any given mRNA sequence, depending on where translation begins. Each reading frame can produce a different sequence of amino acids, leading to distinct proteins, which is essential for analyzing the outcomes of experiments like those conducted by Khorana.
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Trinucleotide Repeats
Trinucleotide repeats are sequences of three nucleotides that are repeated multiple times in a row within a DNA or RNA strand. In the context of Khorana's experiment, the synthetic mRNA containing repeats of UUG would lead to the same codon being read multiple times, affecting the resulting protein's amino acid sequence. This concept is important for understanding how specific sequences influence protein synthesis and function.
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Related Practice
Textbook Question
Har Gobind Khorana and his colleagues performed numerous experiments translating synthetic mRNAs. In one experiment, an mRNA molecule with a repeating UG dinucleotide sequence was assembled and translated.
If the genetic code were a doublet code instead of a triplet code, how would the result of this experiment be different?
Textbook Question
Har Gobind Khorana and his colleagues performed numerous experiments translating synthetic mRNAs. In one experiment, an mRNA molecule with a repeating UG dinucleotide sequence was assembled and translated.
If the genetic code were overlapping rather than nonoverlapping, how would the result of this experiment be different?
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Textbook Question
An experiment by Khorana and his colleagues translated a synthetic mRNA containing repeats of the trinucelotide UUG.
How does the result of this experiment help confirm the triplet nature of the genetic code?
Textbook Question
The human β-globin polypeptide contains 146 amino acids. How many mRNA nucleotides are required to encode this polypeptide?
Textbook Question
The mature mRNA transcribed from the human β-globin gene is considerably longer than the sequence needed to encode the 146–amino acid polypeptide. Give the names of three sequences located on the mature β-globin mRNA but not translated.