Molecular Genetics

Tetrad analysis

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Facets of recombination observable in fungi such as Ascobolus can also be ssen in yeast tetrads.


  • Meiosis inSaccharomyces cerevisiae produces four haploid cells (a tetrad). Each represents one DNA duplex. Each haploid cell product can be cultured individually. In contrast to spore formation in Ascobolus immersus, there is no immediate postmeiotic replication in this yeast.

  • In S. cerevisiae, aberrant segregations (at the B locus, left) (3:1, 1:3, or sectored colonies) are less frequently associated with exchange of flanking markers (A and C loci) than they are in A. immersus.
  • Among the Ab recombination products of sporulation of (ABC/abc) (gene-conversion and PMS events disregarded), one expects to find AbC double recombinants at the same frequency as bC recombinants occur in the total population. A lower frequency is found, particularly for markers that map close to one another. The phenomenon is called cross-over interference.

Facts | Interpretations | Other Pages


Facts | Interpretations | Other Pages

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This is page 3513 of Molecular Genetics by Ulrich Melcher, © 1997, 1998, 2001

E-mail inquiries to U. Melcher------------Last Revised: 18 August, 2003