Biod Exp 4

EXPERIMENT 4: FUNGI a) Characteristics: 1. Fungi are eukaryotic. 2. Their basic body consists of a mass of netlike filaments called hyphae. The entire mass is called mycelium. 3. Most fungal hyphae are divided into cells by cross walls called septa. 4. Some fungi are aseptate, lacking cross walls. b) Diversity There are four divisions of fungi based on variation in reproduction: (i) Zygomycota consists of aseptate Zygomycetes. Asexually, Zygomycetes can reproduce by spores at the tip of hyphae, called sporangia (singular: sporangium). They can also sexually reproduced by producing zygosporangia, which will remain dormant when conditions are not suitable for growth. The black bread mold Rhizopus stolonifer is an example of Zygomycetes. Vegetative (asexual) reproduction of Zygomycetes

(ii) Ascomycetes from Ascomycota have septate mycelium. They can reproduce via vegetative and sexual structures. They are reproducing by chains of spores called conidia at the tip of specialized hyphae conidiophore asexually. An example is Penicillium. The sexual reproductive structure is the ascus (plural: asci), which is a small sac-like structure. These asci are packed into large fruiting structures called ascocarps releasing ascspores. One of the examples of Ascomyteces is Saccharomyces (yeast).

Figure 1: Asexual reproduction of Penicillium. 1

Figure 2: The typical life cycle of Ascomycetes. Step 1 and 2 Step 3 Step 4 Step 5 Step 6 Step 7 Step 8 Step 9 Step 10

: two compatible haploid hyphae become intertwined and form an ascogonium and an antheridium : cup-shaped ascocarp is formed : asci begin to form on the surface of the ascocarp : diploid nucleus is formed : meiosis occurs, producing four haploid nuclei : the ascus now contains eight haploid nuclei after mitosis : the nuclei developed into ascospores and release from the surface of ascocarp : haploid mycelium arises from ascospores : if compatible haploid hypha is absent, the haploid mycelium will produce asexual spores (conidia) by segmentation of its hyphae

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(iii) Basidomycota includes mushroom and puffball. Basidomycetes sexually reproduce by producing basidiospores on basidium.

Figure 3: The typical life cycle of Basidiomycetes. Step 1 and 2 Step 3 Step 4 Step 5 Step 6 Step 7

: two haploid hyphae of opposite mating types fuse to produce a dikaryotic hyphae : the hypha is producing fruiting body under favourable conditions : basidia is forming on the surface of the gills : diploid nucleus is formed in each basidium : meiosis occurs and four haploid nuclei eventually develop into basidiospores : dispersion of basidiospores

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