Reino fungi

Kingdom Fungi

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Characteristics of Fungi Heterotrophic saprobes – cells of hyphae secrete digestive enzymes and absorb products of digestion Cell wall made of chitin - a polysaccharide with added nitrogen group Hypha - filamentous body - forming mycelial mat each hypha is composed of a chain of cells with or without separating septa

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Nuclear mitosis - all stages of mitosis go on within the nucleus - followed by nuclear division and then cell division Some fungi have a dikaryon stage - cells of two different hyphae fuse and the nuclei of each remain distinct within the new hypha

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Reproduction in Fungi
• Differ from most animals and plants in that each compartment of hypha can contain one, two or more nuclei – monokaryotic - each compartment has a single nucleus – dikaryotic - two distinct nuclei within each hyphae compartment • Possible for many nuclei to intermingle in common cytoplasm of fungal mycelium which can lack distinct cells – heterokaryotic – dikaryotic or multinucleate hypha has nuclei from genetically distinct individuals – homokaryotic – hyphae whose nuclei are genetically 4 similar to one another

Fungi have both asexual and sexual reproduction Asexual • fragmentation (breakage) of hyphae can produce new mycelium • production of spores by modified hyphae - spores dispersed by wind Sexual always involves fusion of cells from different mating types (+/-) in some, the cells that fuse are gametes, in others the cells that fuse are part of hyphae in some, fusion produces a diploid zygote, in others the fusion produces a dikaryon, or heterokaryon fusion of nuclei within dikaryon produces diploid zygote nucleus meiosis of zygote produces haploid spores 5

meiosis N 2N gametes

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N meiosis

2N

N

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N+N dikaryon N

nuclear fusion 2N meiosis

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Fungal Ecology Feeding - saprobes - feed on dead or living material - secrete digestive enzymes and absorb products of digestion some are important decomposers can