Chapter 20.2, Problem 7MI

Summary Introduction

To organize: 

The information about the location of the spores of sac fungi.

Introduction:

Ascomycota fungi are also called sac fungi. They are filamentous and produce hyphae divided by septa. Ascomycetes frequently reproduce asexually through conidiophores that release haploid conidiospores and reproduce sexually through ascospores.

Answer to Problem 7MI

Asexual reproduction: Asexual spores formed externally, at the tips of the conidiophores

Sexual reproduction: Sexual spores formed internally, in the ascus.

Explanation of Solution

Sac fungi frequently reproduce asexually by production of conidiophores which are formed from the hyphae. Conidiophores release haploid conidiospores. Sexual reproduction in sac fungi begins with fusion of two different mating strains of hyphae. The fused structure contains two haploid nucleus from each strain. New hyphae are produced with dikaryotic cells. At the tip of the hyphae develops into the ascocarp. The ascocarp contains ascus. In each ascus, two nuclei fuse together form a diploid zygote. The diploid zygote undergoes meiosis to form 4 haploid nuclei, which undergo mitotic division to form 8 haploid ascospores.