Domanda del libro di testo
What observations suggested the existence of mRNA?
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Ch. 13 - The Genetic Code and Transcription
Klug12th EditionConcepts of GeneticsISBN: 9780135564776
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TOC.tableOfContents
- Ch. 1 - Introduction to Genetics17
- Ch. 2 - Mitosis and Meiosis36
- Ch. 3 - Mendelian Genetics51
- Ch. 4 - Extensions of Mendelian Genetics74
- Ch. 5 - Chromosome Mapping in Eukaryotes51
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages46
- Ch. 7 - Sex Determination and Sex Chromosomes33
- Ch. 8 - Chromosome Mutations: Variation in Number and Arrangement40
- Ch. 9 - Extranuclear Inheritance31
- Ch. 10 - DNA Structure and Analysis43
- Ch. 11 - DNA Replication and Recombination44
- Ch. 12 - DNA Organization in Chromosomes30
- Ch. 13 - The Genetic Code and Transcription54
- Ch. 14 - Translation and Proteins47
- Ch. 15 - Gene Mutation, DNA Repair, and Transposition41
- Ch. 16 - Regulation of Gene Expression in Bacteria29
- Ch. 17 - Transcriptional Regulation in Eukaryotes41
- Ch. 18 - Post-transcriptional Regulation in Eukaryotes33
- Ch. 19 - Epigenetics33
- Ch. 20 - Recombinant DNA Technology44
- Ch. 21 - Genomic Analysis36
- Ch. 22 - Applications of Genetic Engineering and Biotechnology36
- Ch. 23 - Developmental Genetics37
- Ch. 24 - Cancer Genetics34
- Ch. 25 - Quantitative Genetics and Multifactorial Traits54
- Ch. 26 - Population and Evolutionary Genetics45
Klug12th EditionConcepts of GeneticsISBN: 9780135564776Non è quello che usi tu?Cambia libro di testo
Capitolo 13, Problema 19
Describe the structure of RNA polymerase in bacteria. What is the core enzyme? What is the role of the σ subunit?
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Begin by explaining that bacterial RNA polymerase is a multi-subunit enzyme responsible for synthesizing RNA from a DNA template during transcription.
Describe the overall structure of bacterial RNA polymerase, which consists of a core enzyme and an additional subunit called sigma (σ). The core enzyme is composed of five subunits: two alpha (\(\alpha\)) subunits, one beta (\(\beta\)), one beta prime (\(\beta\)\'), and one omega (\(\omega\)) subunit.
Clarify that the core enzyme (\(\alpha\)_2\(\beta\)\(\beta\)\'\(\omega\)) is capable of elongating the RNA chain but cannot initiate transcription on its own because it lacks specificity for promoter regions on DNA.
Explain that the sigma (σ) subunit associates with the core enzyme to form the holoenzyme, which is necessary for the initiation phase of transcription. The σ subunit recognizes and binds to specific promoter sequences on the DNA, guiding the RNA polymerase to the correct start site.
Summarize that once transcription is initiated, the σ subunit often dissociates from the core enzyme, allowing the core enzyme to continue RNA synthesis during elongation.
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Structure of Bacterial RNA Polymerase
Bacterial RNA polymerase is a multi-subunit enzyme responsible for synthesizing RNA from a DNA template. It typically consists of a core enzyme made up of five subunits (2 α, β, β', and ω) and a sigma (σ) factor that associates transiently. This complex structure allows the enzyme to perform transcription efficiently.
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Core Enzyme of RNA Polymerase
The core enzyme of bacterial RNA polymerase includes the subunits α2, β, β', and ω. It carries out the catalytic activity of RNA synthesis but cannot initiate transcription on its own. The core enzyme binds to DNA and elongates the RNA chain once transcription has started.
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Role of the Sigma (σ) Subunit
The sigma (σ) subunit is a detachable factor that directs the RNA polymerase core enzyme to specific promoter regions on the DNA. It enables the enzyme to recognize and bind to the correct initiation sites, facilitating the start of transcription. After initiation, the σ subunit often dissociates from the core enzyme.
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Percorso guidato
10:14
Prokaryotic Transcription
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Define the process of transcription. Where does this process fit into the central dogma of molecular biology (DNA makes RNA makes protein)?
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Domanda del libro di testo
Present an overview of various forms of posttranscriptional RNA processing in eukaryotes. For each, provide an example.
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Domanda del libro di testo
Messenger RNA molecules are very difficult to isolate in bacteria because they are rather quickly degraded in the cell. Can you suggest a reason why this occurs? Eukaryotic mRNAs are more stable and exist longer in the cell than do bacterial mRNAs. Is this an advantage or a disadvantage for a pancreatic cell making large quantities of insulin?
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Domanda del libro di testo
Most proteins have more leucine than histidine residues, but more histidine than tryptophan residues. Correlate the number of codons for these three amino acids with this information.
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Domanda del libro di testo
Write a paragraph describing the abbreviated chemical reactions that summarize RNA polymerase-directed transcription.
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