Opening the book…
- 14.0: Introduction
- This page examines somatic mutations' effects on cellular behavior and disease, emphasizing their role in altering gene expression and promoting uncontrolled cell division, a characteristic of tumors and cancer. It outlines the complexity of carcinogenesis, which involves multiple mutations within a clone, leading to competition between mutant and normal cells for resources and space.
- 14.1: Rates and effects of somatic mutation
- This page discusses how mutation rates differ across cell types and species, highlighting the impact of DNA replication, error rates, and repair efficiency. It notes that humans accumulate approximately 100 new mutations in germ line chromosomes. Additionally, somatic mutations can lead to diseases, particularly cancer. In retinoblastoma, a dominant mutation necessitates a second mutation for cancer development.
- 14.2: Non-disjunction- aberrant chromosome segregation
- This page covers non-disjunction, a genetic disorder caused by incorrect chromosome separation, leading to aneuploidy. It addresses its effects in somatic and germline cells, emphasizing the high rate of embryonic lethality linked to chromosomal abnormalities, illustrated by conditions like Down Syndrome. The page also raises inquiries about somatic mutations, checkpoint gene mutations, molecular causes of aneuploidy, and their influence on gene expression and cancer risk.
- 14.3: Genome dynamics
- This page discusses the dynamic nature of the genome, highlighting variations from point mutations, transposable elements, and structural variants, including their impact on meiosis and hybrid sterility. It notes that individuals may possess around 2000 structural variants, with somatic mutations typically lost at death.
- 14.4: Gene duplications and deletions
- This page examines the effects of chromosome misalignment during meiosis, focusing on repeated sequences that can cause gene duplications or deletions in haploid cells. These duplications enhance evolutionary adaptability by increasing gene product output, essential for survival against environmental challenges. Additionally, they enable the retention of vital functions while allowing one gene copy to evolve new roles, which can be advantageous in different situations.
- 14.5: Orthologs and paralogs
- This page covers homologous genes, focusing on orthologs, which arise from a common ancestor, and paralogs, resulting from gene duplication. It explains how gene duplication can create complex gene families with obscured histories. The emergence of microproteins from non-coding regions complicates interspecies comparisons. It also notes that the rate of evolutionary sequence changes varies depending on functional constraints.
- 14.6: Transposons- moving DNA within a genome (and weird genetics)
- This page covers transposable elements (transposons), DNA sequences capable of moving within genomes, first discovered by Barbara McClintock in maize. It explains their potential effects on gene expression, how they are classified into type I and type II based on movement mechanisms, and their role in genetic variation and evolution. Additionally, it notes that a significant part of the human genome comprises inactive transposons, and their random movement can result in population divergence.
This page titled 14: Somatic Mutations and Genome Dynamics was last modified on Thu, 08 Jan 2026 22:57:29 GMT and is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Michael W. Klymkowsky and Melanie M. Cooper.
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