Phylum Ascomycota

What are the distinguishing characteristics of a Cleistothcium?

A cleistothecium has an ascocarp that is completely closed. The ascocarp is small and inconspicuous. The asci are scattered and not in a hymenium.

What are the distinguishing characteristics of a Perithecium?

A perithecium has a flask shaped (look like a pear) ascocarp with a pore at the top. The asci arise from a basal tuft for a hymenium. These are large and macroscopic.

Describe the structure of the conidiophore of Aspergillus.

Aspergillus conidiophores are conneteced to a vegetative hyphae that gives rise to the conidiophore, which then ends in a bulbous structure called a vesicle. The vesicle is surrounded by conidia.

What are the three types of Ascomata?

Cleistothecium, Perithecium, and Apothecium.

Describe the asexual reproduction of filamentous ascomycetes (conidial fungi).

In asexual reproduction, the spores are elevated and terrestrial. The spores are called conidiospores or conidia that are elevated in a conidiophore. There are nine types of conidiospores. The base of the conidiophore is connected to a filament referred to as the vegetative hyphae.

Describe the habitat of most members of this phylum.

Most are saprobes, many are plant pathogens, some are animal/human pathogens, and a few are mycorrhizal.

Describe the structure of the conidiophore of Penicillium.

Penicillium conidionphores are connected to a vegetative hyphae, which then gives rise to the conidiophore. The conidiophore then produces one ascus at a time. The asexual fruit body looks like weird wheat.

Who is in this phylum?

Specialized plant pathogens, yeasts, and filamentous ascoma producing species-the most of which are lichens.

How do conidiospores develop?

The development of conidiospores is basipetal- meaning the youngest is at the base of the conidia and they develop in a chain.

What are the binding characteristics of Ascomycota?

The result of sexual reproduction is the formation of a saclike structure called an ascus (pl. asci) which contains haploid sexual spores called ascospores (typically 8 per ascus).

Describe the thallus of most memebers of ascomycota.

The thallus is mycelial and regularly septate with a haploid nucleus per cell. The septum is perferated with a centeral perferation to nuclei can migrate cell to cell. Yeasts are unicellular. The thallus has no flagellated cell and no basal bodies or centrioles. The cell wall is made of chitin and was ONCE placed in the red line of evolution.

What are the defining characteristics of yeast?

Yeast has a reduced or absent mycelium; most are unicellular, and has no ascocarp- the asci are naked. Instead, the asci develop directly from the zygote without the intervention of ascogenous hyphae.

What are the distinguishing characteristics of an apothecium?

An apothecium is a cup shaped or saucer shaped ascocarp. The asci occur in a hymenium that is fully exposed at maturity. They may or may not have a stem. The hymenium can fold back to form a false morel.

Describe the haploid life cycle of the typical Ascomycete.

Beginning with a young ascus, the ascus undergoes karyogamy-is dikaryotic- and then self-fertilizes, meitotic division then occurs to form 4ascospores. The 4 ascospores then undergo mitotic division to form 8 haploid ascospores within the mature ascus. These are then forcibly disharged and germinate. The germinating ascopores can then reproduce asexually of desired and form a conidiophore. The conidiophore can participate in sexual reproduction by developing both male and female gametangia. Once mature, the ascogonium then uses its trichogyne to connect to the antheridium and initiate plasmogamy. Once plasmogany occurs, more dikaryotic ascogenous hyphae develop. The then continue to develope and grow until they for an ascoma, where they are contained within it.

What are the main points of the life cycle of the typical ascomycete?

It is a haploid life cycle, is homo or hetero thallic, has modified oogamy in called gametangial contact- the sperm is not motile-, the female gametangium is called a ascogonium with a trichogyne (hair), the male gametangium is referred to as a antheridium. The asci are formed from ascogenous hyphae, which are dikaryotic. All of the asci are within a ascocarp (fruit body) or ascoma. Asexual reproduction occurs via conidiospores or conidia.

What are the two main groups within Acomycota?

The Sac Fungi and the Ascomycetes.

What are the two methods of asexual reproduction of yeast?

The asexual reproduction of yeast can occur via budding or fission. Budding is when the cell forms a bud that develops and then undergoes mitosis so that each cell has a nucleus. Fission is when the wall begins to grow, the cell undergoes mitosis, cytokenisis occurs and the two seperate when the wall forms.