Tetrad includes which dna strands

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Share Question Copy Link. Need the answer? Create an account to get free access. Sign Up Free. Log in to watch this video As the invading strand is extended, a remarkable structure called synaptonemal complex SC develops around the paired homologues and holds them in close register, or synapsis.

The stability of the SC increases as the invading strand first extends into the homologue and then is recaptured by the broken chromatid, forming double Holliday junctions. Investigators have been able to observe the process of SC formation with electron microscopy in meiocytes from the Allium plant Figure 6.

Bridges approximately nanometers long begin to form between the paired homologues following the DSB. Only a fraction of these bridges will mature into SC; moreover, not all Holliday junctions will mature into crossover sites.

Gerton, J. Homologous chromosome interactions in meiosis: Diversity amidst conservation. Nature Reviews Genetics 6 , — doi Hassold, T.

To err meiotically is human: The genesis of human aneuploidy. Nature Reviews Genetics 2 , — doi Lopez-Maury, L. Tuning gene expression to changing environments: From rapid responses to evolutionary adaptation. Nature Reviews Genetics 9 , — doi Marston, A. Meiosis: Cell-cycle controls shuffle and deal. Nature Reviews Molecular Cell Biology 5 , — doi Page, S. Chromosome choreography: The meiotic ballet.

Science , — Petes, T. Meiotic recombination hot spots and cold spots. Zickler, D. Meiotic chromosomes: Integrating structure and function. Annual Review of Genetics 33 , — Chromosome Mapping: Idiograms. Human Chromosome Translocations and Cancer. Karyotyping for Chromosomal Abnormalities. Prenatal Screen Detects Fetal Abnormalities. Synteny: Inferring Ancestral Genomes. Telomeres of Human Chromosomes. Chromosomal Abnormalities: Aneuploidies. Chromosome Abnormalities and Cancer Cytogenetics.

Copy Number Variation and Human Disease. Genetic Recombination. Human Chromosome Number. Trisomy 21 Causes Down Syndrome. X Chromosome: X Inactivation. Chromosome Theory and the Castle and Morgan Debate.

Developing the Chromosome Theory. Meiosis, Genetic Recombination, and Sexual Reproduction. Mitosis and Cell Division. Genetic Mechanisms of Sex Determination. Sex Chromosomes and Sex Determination. Sex Chromosomes in Mammals: X Inactivation. Sex Determination in Honeybees. Citation: O'Connor, C. Nature Education 1 1 How is the same process responsible for genetic recombination and diversity also the cause of aneuploidy?

Understanding the steps of meiosis is essential to learning how errors occur. Aa Aa Aa. Figure 1. Figure Detail. Meiosis Is a Highly Regulated Process. Figure 2. Meiosis I. Figure 3. Meiosis II. Figure 4. Figure 5. Figure 6: Visualization of chromosomal bridges in Allium fistulosum and Allium cepa plant meiocytes.

The sites of double-stranded break DSB dependent homologue interaction can be seen as approximately nm bridges between chromosome axes. These bridges, which probably contain a DSB that is already engaged in a nascent interaction with its partner DNA, occur in large numbers.

Their formation depends on the RecA recombination protein homologues that are expressed in this species. In the next phase of homologue interaction, these nascent interactions are converted to stable strand-invasion events. This nucleates the formation of the synaptonemal complex SC. Homologous chromosome interactions in meiosis: diversity amidst conservation.

Nature Reviews Genetics 6, All rights reserved. References and Recommended Reading Gerton, J. Science , — Petes, T. Article History Close. Share Cancel. Revoke Cancel. Keywords Keywords for this Article. Save Cancel. Flag Inappropriate The Content is: Objectionable. Flag Content Cancel. Email your Friend. Submit Cancel. This content is currently under construction. Explore This Subject. Chromosome Analysis. Chromosome Structure. Mutations and Alterations in Chromosomes.

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