An ascus (plural asci) is the spore-bearing container produced in the ascocarps of ascomycete fungi. Each ascus contains eight ascospores, produced by a meiotic cell division followed by a mitotic cell division. Asci release their spores by bursting. When one ascus bursts, it triggers the bursting of all the other asci in the ascocarp. This is an example of positive feedback. An ascocarp is the fruiting body of some ascomycete fungi, containing millions of asci, each of which contains typically eight ascospores. ... Classes Archaeascomycetes Discomycetes Euascomycetes Hemiascomycetes Lecanoromycetes Neolectomycetes Pezizomycotina Pneumocystidomycetes Saccharomycotina Schizosaccharomycetes Taphrinomycetes Mitosporic Ascomycota Members of the Division Ascomycota are known as the Sac Fungi and are fungi that produce spores in a distinctive type of microscopic sporangium called an ascus (Greek for a bag or wineskin). This monophyletic grouping... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... An ascospore is a spore contained in an ascus or that was produced inside an ascus. ... In biology, meiosis is the process that transforms one diploid cell into four haploid cells in eukaryotes in order to redistribute the diploids cells genome. ... Light micrograph of a newt lung cell in early anaphase of mitosis. ... Positive feedback is a type of feedback. ...

Asci, notably those of Neurospora crassa, have been used in laboratories for studying the process of meiosis, because the four cells produced by meiosis line up in regular order. By modifying a gene coding for spore color, the biologist can study crossing over and other phenomena. Binomial name Neurospora crassa Neurospora crassa is a type of red bread mold of the phylum Ascomycota. ... Cells in culture, stained for keratin (red) and DNA (green) The cell is the structural and functional unit of all living organisms, and are sometimes called the building blocks of life. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... Chromosomal crossover is the process by which two chromosomes, paired up during Prophase I of meiosis, exchange some distal portion of their DNA. Crossover occurs when two chromosomes, normally two homologous instances of the same chromosome, break and then reconnect but to the different end piece. ...