Textbook Question
What experimental evidence provided the initial insights into the compositions of codons encoding specific amino acids?
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Ch. 12 - The Genetic Code and Transcription
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 12, Problem 1d
How do we know that mRNA exists and serves as an intermediate between information encoded in DNA and its concomitant gene product?
Verified step by step guidance1
Understand the central dogma of molecular biology, which states that genetic information flows from DNA to RNA to protein, implying the existence of an intermediate molecule (mRNA) that carries information from DNA to the protein synthesis machinery.
Examine experimental evidence such as pulse-chase experiments where cells are exposed to radioactive nucleotides for a short time (pulse) and then non-radioactive nucleotides (chase), allowing tracking of newly synthesized RNA and proteins to show that RNA appears before protein synthesis.
Consider the discovery of different types of RNA, including messenger RNA (mRNA), which was identified as a transient RNA species that carries the genetic code from DNA in the nucleus to ribosomes in the cytoplasm where proteins are made.
Review experiments where inhibition of RNA synthesis (using drugs like actinomycin D) leads to a halt in protein synthesis, indicating that RNA is necessary as an intermediate for protein production.
Analyze the molecular characteristics of mRNA, such as its sequence complementarity to DNA and its ability to be translated by ribosomes, confirming its role as the intermediate between DNA and protein.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Central Dogma of Molecular Biology
The central dogma describes the flow of genetic information from DNA to RNA to protein. It establishes mRNA as the intermediate molecule that carries the genetic code from DNA in the nucleus to ribosomes in the cytoplasm, where proteins are synthesized.
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07:11
Mapping with Markers
Experimental Evidence for mRNA
Experiments such as pulse-chase labeling and hybridization techniques demonstrated the existence of mRNA. These studies showed that RNA molecules complementary to DNA sequences appear transiently and associate with ribosomes, confirming mRNA’s role as a messenger.
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Guided course
08:39mRNA Processing
Transcription and Translation Processes
Transcription is the process where DNA is copied into mRNA, which then exits the nucleus. Translation is the subsequent decoding of mRNA by ribosomes to produce proteins, linking the genetic code to functional gene products.
Recommended video:
Guided course
08:39mRNA Processing
Related Practice
Textbook Question
How were the specific sequences of triplet codes determined experimentally?
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Textbook Question
How were the experimentally derived triplet codon assignments verified in studies using bacteriophage MS2?
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Textbook Question
Write a short essay that summarizes the key properties of the genetic code and the process by which RNA is transcribed on a DNA template.
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Textbook Question
Assuming the genetic code is a triplet, what effect would the addition or loss of two nucleotides have on the reading frame? The addition or loss of three, six, or nine nucleotides?
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