Meiosis and fertilization create genetic variation by making new combinations of gene variants alleles. In some cases, these new combinations may make an organism more or less fit able to survive and reproduce , thus providing the raw material for natural selection. Genetic variation is important in allowing a population to adapt via natural selection and thus survive in the long term. Improve this page Learn More.
Skip to main content. Module 8: Cell Division. Search for:. Genetic Variation in Meiosis Learning Outcomes Understand how meiosis contributes to genetic diversity.
Likewise, abnormal separation can occur in meiosis when homologous pairs fail to separate during anaphase I. This also results in daughter cells with different numbers of chromosomes. The phenomenon of unequal separation in meiosis is called nondisjunction. If nondisjunction causes a missing chromosome in a haploid gamete, the diploid zygote it forms with another gamete will contain only one copy of that chromosome from the other parent, a condition known as monosomy.
Conversely, if nondisjunction causes a homologous pair to travel together into the same gamete, the resulting zygote will have three copies, a condition known as trisomy Figure 3. The term " aneuploidy " applies to any of these conditions that cause an unexpected chromosome number in a daughter cell. Aneuploidy can also occur in humans. For instance, the underlying causes of Klinefelter's syndrome and Turner's syndrome are errors in sex chromosome number, and Down syndrome is caused by trisomy of chromosome However, the severity of phenotypic abnormalities can vary among different types of aneuploidy.
In addition, aneuploidy is rarely transferred to subsequent generations, because this condition impairs the production of gametes. Overall, the inheritance of odd chromosome number arises from errors in segregation during chromosome replication. Often, it is these very exceptions or modifications of expected patterns in mitosis and meiosis that enrich our understanding of how the transfer of chromosomes is regulated from one generation to the next.
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Hirsch, J. Behavior genetics and individuality understood. Science 42 , — doi Uniqueness, diversity, similarity, repeatability, and heritability. International Journal of Comparative Psychology 17 , — Paweletz, N. Walther Flemming: Pioneer of mitosis research. Nature Reviews Molecular Cell Biology 2 , 72—75 doi Chromosome Theory and the Castle and Morgan Debate. Discovery and Types of Genetic Linkage.
Genetics and Statistical Analysis. Thomas Hunt Morgan and Sex Linkage. Developing the Chromosome Theory. Genetic Recombination. Gregor Mendel and the Principles of Inheritance. Mitosis, Meiosis, and Inheritance. Multifactorial Inheritance and Genetic Disease. Non-nuclear Genes and Their Inheritance. Polygenic Inheritance and Gene Mapping. Sex Chromosomes and Sex Determination. Sex Determination in Honeybees.
Test Crosses. Biological Complexity and Integrative Levels of Organization. Genetics of Dog Breeding. Human Evolutionary Tree. Mendelian Ratios and Lethal Genes. Environmental Influences on Gene Expression. Epistasis: Gene Interaction and Phenotype Effects. Genetic Dominance: Genotype-Phenotype Relationships. Phenotype Variability: Penetrance and Expressivity. Citation: Miko, I. Nature Education 1 1 Although mitosis and meiosis both involve cell division, they transmit genetic material in very different ways.
What happens when either of these processes goes awry? Aa Aa Aa. Gene Transmission in Mitosis. Figure 1. Gene Transmission in Meiosis. Denise Granger. Feb 17, Prophase 1. Explanation: It occurs during the crossing over process in prophase 1 of meiosis.
Related questions How does meiosis 1 differ from meiosis 2? What is meiosis? How many chromosomes are present in telophase ii? Why does nondisjunction cause mutation? How does aneuploidy differ from polyploidy? What is aneuploidy?
How does trisomy 18 affect a person?
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