Biology 110 Sordaria LAb

Biology 110 Sordaria LAb - Ian Allender Biology 110 Lab...

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Ian Allender Biology 110 – Lab Section 039 Jennifer Boulay 29 September 2010 Examining the Frequencies of Expected and Anomalous Asci Patterns in Sordaria Introduction: In this lab we worked with a haploid fungus (1N) called Sordaria fimicola . S. fimicola is an interesting and convenient organism for studying genetics. The products of each complete meiotic event and a subsequent mitosis of each nuclei are 8 haploid spores (reproductive structures adapted for dispersal) contained in elongated sac-like structures called asci. These asci are contained in perithecia, which can be easily removed from the organism, placed on a microscope slide with water, and squashed to expose the elongate asci in an easy to view ray-like pattern. By examining the contents of the asci, scientists can study the products of meiosis (Hass, 2006). Spore color is an observable gene in Sordaria, displaying colors of either black or tan. One of the chromosomes in Sordaria will contain this gene. The black spore producing stain of Sordaria is the wild type, while the tan spore producing strain is considered the mutant strain. Several strains (a genetic variant) of S. fimicola have been found that have different spore colors. When scientists first crossed a wild type strain of S. fimicola with a black spore coat (W) with another strain with a tan spore coat (T), they discovered an interesting finding. They had expected to find asci containing 8 spores in just two possible combinations: WWWWTTTT or TTTTWWWW. They discovered, in addition, four anomalous (abnormal or unexpected) combinations: WWTTWWTT; TTWWTTWW;
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TTWWWWTT; and WWTTTTWW (Figure 2), but not WTWTWTWTWT or TWTWTWTWTW (Hass,2006). These unexpected combinations are due to crossing over. The distance between a gene and the centromere of a chromosome determines how
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Biology 110 Sordaria LAb - Ian Allender Biology 110 Lab...

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