Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgments
- Chapter 1 Life Forms and Their Origins
- Chapter 2 Nucleic Acids
- Chapter 3 Proteins
- Chapter 4 Simple Chromosomes
- Chapter 5 Chromosomes of Eukarya
- Chapter 6 Genome Content
- Chapter 7 RNA Synthesis 1: Transcription
- Chapter 8 RNA Synthesis 2: Processing
- Chapter 9 Abundance of RNAs in Bacteria
- Chapter 10 Abundance of RNAs in Eukarya
- Chapter 11 Protein Synthesis
- Chapter 12 DNA Replication
- Chapter 13 Chromosome Replication
- Chapter 14 Molecular Events of Recombination
- Chapter 15 Micromutations
- Chapter 16 Repair of Altered DNA
- Chapter 17 Reproduction of Bacteria
- Chapter 18 Horizontal Gene Transfer in Bacteria
- Chapter 19 Cell Cycles of Eukarya
- Chapter 20 Meiosis
- Chapter 21 Chromosomal Abnormalities
- Chapter 22 Life Cycles of Eukarya
- Chapter 23 Reproduction of Viruses
- Chapter 24 Genetic Processes in Development
- Chapter 25 Sex Determination and Dosage Compensation
- Chapter 26 Cancer
- Chapter 27 Cutting, Sorting, and Copying DNA
- Chapter 28 Genotyping by DNA Analysis
- Chapter 29 Genetically Engineered Organisms
- Chapter 30 Genomics
- Chapter 31 Behavior of Genes and Alleles
- Chapter 32 Probability and Statistics Toolkit
- Chapter 33 Genes, Environment, and Interactions
- Chapter 34 Locating Genes
- Chapter 35 Finding and Detecting Mutations
- Chapter 36 Cytoplasmic Inheritance
- Chapter 37 Genetic Variation in Populations
- Chapter 38 Mutation, Migration, and Genetic Drift
- Chapter 39 Natural Selection
- Chapter 40 Quantitative Genetics
- Chapter 41 Speciation
- Chapter 42 Molecular Evolution and Phylogeny
- Glossary
- Index
Chapter 10 - Abundance of RNAs in Eukarya
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- Acknowledgments
- Chapter 1 Life Forms and Their Origins
- Chapter 2 Nucleic Acids
- Chapter 3 Proteins
- Chapter 4 Simple Chromosomes
- Chapter 5 Chromosomes of Eukarya
- Chapter 6 Genome Content
- Chapter 7 RNA Synthesis 1: Transcription
- Chapter 8 RNA Synthesis 2: Processing
- Chapter 9 Abundance of RNAs in Bacteria
- Chapter 10 Abundance of RNAs in Eukarya
- Chapter 11 Protein Synthesis
- Chapter 12 DNA Replication
- Chapter 13 Chromosome Replication
- Chapter 14 Molecular Events of Recombination
- Chapter 15 Micromutations
- Chapter 16 Repair of Altered DNA
- Chapter 17 Reproduction of Bacteria
- Chapter 18 Horizontal Gene Transfer in Bacteria
- Chapter 19 Cell Cycles of Eukarya
- Chapter 20 Meiosis
- Chapter 21 Chromosomal Abnormalities
- Chapter 22 Life Cycles of Eukarya
- Chapter 23 Reproduction of Viruses
- Chapter 24 Genetic Processes in Development
- Chapter 25 Sex Determination and Dosage Compensation
- Chapter 26 Cancer
- Chapter 27 Cutting, Sorting, and Copying DNA
- Chapter 28 Genotyping by DNA Analysis
- Chapter 29 Genetically Engineered Organisms
- Chapter 30 Genomics
- Chapter 31 Behavior of Genes and Alleles
- Chapter 32 Probability and Statistics Toolkit
- Chapter 33 Genes, Environment, and Interactions
- Chapter 34 Locating Genes
- Chapter 35 Finding and Detecting Mutations
- Chapter 36 Cytoplasmic Inheritance
- Chapter 37 Genetic Variation in Populations
- Chapter 38 Mutation, Migration, and Genetic Drift
- Chapter 39 Natural Selection
- Chapter 40 Quantitative Genetics
- Chapter 41 Speciation
- Chapter 42 Molecular Evolution and Phylogeny
- Glossary
- Index
Summary
Overview
Eukarya, like bacteria, regulate the amounts of rRNA, tRNA, and mRNA by controlling rates of synthesis and degradation. On the synthesis side, control is exerted in transcription and splicing. Degradation is controlled by RNases, and is influenced by RNA processing.
The rate-limiting binding step of transcription is complicated both by the inaccessibility of DNA in chromatin and by large genome size. Transcription goes hand in hand with the disassembly of chromatin, and a large genome requires a large number of regulatory DNA sequences and transcription factors. Chromatin disassembly is effected by the chemical modification of histones and by the actions of chromatin remodeling complexes.
RNA Degradation
Stable versus Unstable RNAs
Like bacteria, eukarya have much more stable RNA than unstable RNA. The cytoplasmic RNA of a human cell is ≈80% rRNA, ≈15% tRNA and other small RNAs, and ≈1% to 5% mRNA. In growing eukaryal cells, 50% to 70% of transcription is from class I genes (big rRNAs), 20% to 40% of transcription is from mRNA genes, and the remaining 10% is from class III genes (tRNA and other small RNAs). The rarity of mRNA compared with the rate of transcription by RNA polymerase II reflects the short half-life of eukaryal mRNAs.
mRNA Degradation
Capping and polyadenylation increase RNA's resistance to degradation. These modifications are significant in mRNA, because virtually all mRNAs are capped, and most are polyadenylated.
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- Information
- Fundamental Genetics , pp. 85 - 95Publisher: Cambridge University PressPrint publication year: 2004