Textbook Question
What does a bacterial RNA polymerase produce when it transcribes a protein-coding gene?
a. rRNA
b. tRNA
c. mRNA
d. snRNA
Ch. 17 - Transcription, RNA Processing, and Translation
Freeman8th EditionBiological ScienceISBN: 9780138276263
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Table of contents
- Ch. 1 - Biology: The Study of Life13
- Ch. 2 - Water and Carbon: The Chemical Basis of Life14
- Ch.3 - Protein Structure and Function10
- Ch.4 - Nucleic Acids and the RNA World10
- Ch. 5 - An Introduction to Carbohydrates10
- Ch. 6 - Lipids, Membranes, and the First Cells11
- Ch. 7 - Inside the Cell10
- Ch. 8 - Energy and Enzymes: An Introduction to Metabolism10
- Ch. 9 - Cellular Respiration and Fermentation11
- Ch. 10 - Photosynthesis12
- Ch. 11 - Cell-Cell Interactions12
- Ch. 12 - The Cell Cycle8
- Ch. 13 - Meiosis12
- Ch. 14 - Mendel and the Gene23
- Ch. 15 - DNA and the Gene: Synthesis and Repair15
- Ch. 16 - How Genes Work16
- Ch. 17 - Transcription, RNA Processing, and Translation16
- Ch. 18 - Control of Gene Expression in Bacteria16
- Ch. 19 - Control of Gene Expression in Eukaryotes12
- Ch. 20 - The Molecular Revolution: Biotechnology, Genomics, and New Frontiers15
- Ch. 21 - Genes, Development, and Evolution12
- Ch. 22 - Evolution by Natural Selection16
- Ch. 23 - Evolutionary Processes13
- Ch. 24 - Speciation15
- Ch. 25 - Phylogenies and the History of Life13
- Ch. 26 - Bacteria and Archaea15
- Ch. 27 - Diversification of Eukaryotes16
- Ch. 28 - Green Algae and Land Plants16
- Ch. 29 - Fungi18
- Ch. 30 - An Introduction to Animals9
- Ch. 31 - Protostome Animals15
- Ch. 32 - Deuterostome Animals17
- Ch. 33 - Viruses16
- Ch. 34 - Plant Form and Function16
- Ch. 35 - Water and Sugar Transport in Plants16
- Ch. 36 - Plant Nutrition13
- Ch. 37 - Plant Sensory Systems, Signals, and Responses16
- Ch. 38 - Flowering Plant Reproduction and Development16
- Ch. 39 - Animal Form and Function17
- Ch. 40 - Water and Electrolyte Balance in Animals16
- Ch. 41 - Animal Nutrition16
- Ch. 42 - Gas Exchange and Circulation16
- Ch. 43 - Animal Nervous Systems16
- Ch. 44 - Animal Sensory Systems16
- Ch. 45 - Animal Movement11
- Ch. 46 - Chemical Signals in Animals16
- Ch. 47 - Animal Reproduction and Development16
- Ch. 48 - The Immune System in Animals16
- Ch. 49 - An Introduction to Ecology15
- Ch. 50 - Behavioral Ecology16
- Ch. 51 - Population Ecology16
- Ch. 52 - Community Ecology20
- Ch. 53 - Ecosystems and Global Ecology17
- Ch. 54 - Biodiversity and Conservation Ecology18
Chapter 17, Problem 2
Where is the start codon located?
a. At the start (5′ end) of the mRNA
b. In the DNA just upstream of where transcription starts
c. At the downstream end of the 5′ untranslated region (UTR)
d. At the upstream end of the 3′ untranslated region (UTR)
Verified step by step guidance1
Understand the role of the start codon: The start codon is a specific sequence of three nucleotides (AUG in most cases) that signals the beginning of translation, where the ribosome starts synthesizing a protein.
Recall the structure of mRNA: mRNA has a 5′ untranslated region (UTR), a coding sequence, and a 3′ untranslated region (UTR). The start codon is part of the coding sequence, not the untranslated regions.
Identify the location of the start codon: The start codon is located at the downstream end of the 5′ untranslated region (UTR), marking the transition from the UTR to the coding sequence.
Eliminate incorrect options: a) The start codon is not at the very start (5′ end) of the mRNA, as the 5′ UTR precedes it. b) It is not in the DNA upstream of transcription, as the start codon is part of the mRNA. d) It is not at the upstream end of the 3′ UTR, as the 3′ UTR is downstream of the coding sequence.
Conclude that the correct answer is c) at the downstream end of the 5′ untranslated region (UTR), as this is where the start codon is located in the mRNA.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Start Codon
The start codon is a specific sequence of nucleotides in mRNA that signals the beginning of translation. It is typically the codon AUG, which codes for the amino acid methionine. The presence of the start codon is crucial for ribosomes to initiate protein synthesis.
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1) Initiation of Translation
mRNA Structure
Messenger RNA (mRNA) is a single-stranded molecule that carries genetic information from DNA to the ribosome, where proteins are synthesized. The 5' end of mRNA is capped, and it contains a 5' untranslated region (UTR) before the start codon, which plays a role in the regulation of translation.
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Transcription and Translation
Transcription is the process by which DNA is copied into mRNA, while translation is the subsequent process where ribosomes read the mRNA sequence to synthesize proteins. The start codon is essential in translation as it marks the site where the ribosome begins to assemble amino acids into a polypeptide chain.
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Related Practice
Textbook Question
Splicing begins:
a. As transcription occurs.
b. After transcription is complete.
c. As translation occurs.
d. After translation is complete.
Textbook Question
Compared with mRNAs that have a cap and tail, predict what will be observed if a eukaryotic mRNA lacked a cap and poly(A) tail.
a. The primary transcript would not be processed properly.
b. Translation would occur inefficiently.
c. Enzymes on the ribosome would add a cap and poly(A) tail.
d. tRNAs would become more resistant to degradation.
Textbook Question
RNases and proteases are enzymes that destroy RNAs and proteins, respectively. Which of the following enzymes, if added to a spliceosome, would be predicted to prevent recognition of pre-mRNA regions critical for splicing?
a. An RNase specific for tRNAs
b. An RNase specific for snRNAs
c. A protease specific for initiation factors
d. A protease specific for a release factor