banner



Home  ›  Which Of The Comparisons Of Fungal And Animal Nutrition Is Correct?

Which Of The Comparisons Of Fungal And Animal Nutrition Is Correct?

Written By Sunday, June 12, 2022 Add Comment Edit

Fungi

Classifications of Fungi

OpenStaxCollege

[latexpage]

Learning Objectives

By the terminate of this department, yous will be able to:

  • Classify fungi into the five major phyla
  • Describe each phylum in terms of major representative species and patterns of reproduction

The kingdom Fungi contains v major phyla that were established according to their mode of sexual reproduction or using molecular information. Polyphyletic, unrelated fungi that reproduce without a sexual cycle, are placed for convenience in a sixth group chosen a "grade phylum". Non all mycologists agree with this scheme. Rapid advances in molecular biology and the sequencing of 18S rRNA (a function of RNA) continue to show new and unlike relationships between the various categories of fungi.

The five true phyla of fungi are the Chytridiomycota (Chytrids), the Zygomycota (conjugated fungi), the Ascomycota (sac fungi), the Basidiomycota (lodge fungi) and the recently described Phylum Glomeromycota. An older classification scheme grouped fungi that strictly use asexual reproduction into Deuteromycota, a group that is no longer in use.

Annotation: "-mycota" is used to designate a phylum while "-mycetes" formally denotes a class or is used informally to refer to all members of the phylum.

Chytridiomycota: The Chytrids

The but course in the Phylum Chytridiomycota is the Chytridiomycetes. The chytrids are the simplest and most primitive Eumycota, or true fungi. The evolutionary tape shows that the first recognizable chytrids appeared during the late pre-Cambrian period, more than 500 million years ago. Like all fungi, chytrids accept chitin in their cell walls, but one group of chytrids has both cellulose and chitin in the jail cell wall. Most chytrids are unicellular; a few form multicellular organisms and hyphae, which have no septa between cells (coenocytic). They produce gametes and diploid zoospores that swim with the assist of a single flagellum.

The ecological habitat and jail cell structure of chytrids have much in mutual with protists. Chytrids usually live in aquatic environments, although some species live on land. Some species thrive as parasites on plants, insects, or amphibians ([link]), while others are saprobes. The chytrid species Allomyces is well characterized as an experimental organism. Its reproductive bike includes both asexual and sexual phases. Allomyces produces diploid or haploid flagellated zoospores in a sporangium.

The chytrid Batrachochytrium dendrobatidis is seen in these light micrographs every bit transparent spheres growing on (a) a freshwater arthropod and (b) algae. This chytrid causes skin diseases in many species of amphibians, resulting in species reject and extinction. (credit: modification of piece of work by Johnson ML, Speare R., CDC)


Micrograph A shows an arthropod, which is a teardrop-shaped transparent organism about 90 microns across and 120 microns long. Tentacle-like appendages jut out from the front, wide end of the organism, and clusters of cilia-like appendages just out from either side and the back. Transparent oval organisms about 20 microns across cling to the arthropod. Micrograph B shows a similar oval transparent organisms clinging to rod-shaped algae about 5 microns across and 200 microns long.

Zygomycota: The Conjugated Fungi

The zygomycetes are a relatively small group of fungi belonging to the Phylum Zygomycota. They include the familiar staff of life mold, Rhizopus stolonifer, which rapidly propagates on the surfaces of breads, fruits, and vegetables. Most species are saprobes, living off decaying organic material; a few are parasites, especially of insects. Zygomycetes play a considerable commercial part. The metabolic products of other species of Rhizopus are intermediates in the synthesis of semi-synthetic steroid hormones.

Zygomycetes have a thallus of coenocytic hyphae in which the nuclei are haploid when the organism is in the vegetative phase. The fungi commonly reproduce asexually by producing sporangiospores ([link]). The black tips of bread mold are the swollen sporangia packed with black spores ([link]). When spores land on a suitable substrate, they germinate and produce a new mycelium. Sexual reproduction starts when conditions become unfavorable. Two opposing mating strains (blazon + and type –) must be in close proximity for gametangia from the hyphae to exist produced and fuse, leading to karyogamy. The developing diploid zygospores accept thick coats that protect them from desiccation and other hazards. They may remain dormant until environmental atmospheric condition are favorable. When the zygospore germinates, it undergoes meiosis and produces haploid spores, which will, in plow, abound into a new organism. This form of sexual reproduction in fungi is called conjugation (although it differs markedly from conjugation in bacteria and protists), giving rise to the proper name "conjugated fungi".

Zygomycetes take asexual and asexual life cycles. In the sexual life cycle, plus and minus mating types conjugate to class a zygosporangium.


The asexual and sexual life cycles of zygomycetes are shown. In the asexual life cycle, 1n spores undergo mitosis to form long chains of cells called mycelia. Germination results in the formation of more spores. In the sexual life cycle, spores germinate to form mycelia with two different mating types: plus and minus. If the plus and minus mating types are in close proximity, extensions called gametangia form between them. In a process called plasmogamy, the gametangia fuse to form a zygosporangium with multiple haploid nuclei. A thick, protective coat forms around the zygosporangium. In a process called karyogamy, the nuclei fuse to form a zygote with multiple diploid (2n) nuclei. The zygote undergoes meiosis and germination. A sporangium grows on a short stalk. Haploid spores are formed inside. The spores germinate, ending the cycle.

Sporangia grow at the end of stalks, which appear equally (a) white fuzz seen on this staff of life mold, Rhizopus stolonifer. The (b) tips of breadstuff mold are the spore-containing sporangia. (credit b: modification of work past "polandeze"/Flickr)


The photo shows a thick layer of green mold growing on bread. Fuzzy white projections grow from the mold.

Ascomycota: The Sac Fungi

The bulk of known fungi belong to the Phylum Ascomycota, which is characterized past the formation of an ascus (plural, asci), a sac-like structure that contains haploid ascospores. Many ascomycetes are of commercial importance. Some play a benign role, such equally the yeasts used in blistering, brewing, and wine fermentation, plus truffles and morels, which are held equally gourmet delicacies. Aspergillus oryzae is used in the fermentation of rice to produce sake. Other ascomycetes parasitize plants and animals, including humans. For example, fungal pneumonia poses a pregnant threat to AIDS patients who have a compromised immune system. Ascomycetes not merely infest and destroy crops directly; they also produce poisonous secondary metabolites that make crops unfit for consumption. Filamentous ascomycetes produce hyphae divided by perforated septa, allowing streaming of cytoplasm from one cell to the other. Conidia and asci, which are used respectively for asexual and sexual reproductions, are normally separated from the vegetative hyphae by blocked (non-perforated) septa.

Asexual reproduction is frequent and involves the production of conidiophores that release haploid conidiospores ([link]). Sexual reproduction starts with the development of special hyphae from either one of two types of mating strains ([link]). The "male" strain produces an antheridium and the "female" strain develops an ascogonium. At fertilization, the antheridium and the ascogonium combine in plasmogamy without nuclear fusion. Special ascogenous hyphae arise, in which pairs of nuclei migrate: i from the "male" strain and one from the "female" strain. In each ascus, 2 or more haploid ascospores fuse their nuclei in karyogamy. During sexual reproduction, thousands of asci fill a fruiting body called the ascocarp. The diploid nucleus gives rise to haploid nuclei by meiosis. The ascospores are then released, germinate, and form hyphae that are disseminated in the environment and start new mycelia ([link]).

Art Connectedness

The lifecycle of an ascomycete is characterized by the production of asci during the sexual stage. The haploid stage is the predominant phase of the life cycle.


Ascomycetes have both sexual and asexual life cycles. In the asexual life cycle, the haploid (1n) mycelium branches into a chain of cells called the conidiophore. Spores bud from the end of the conidiophore and germinate to form more mycelia. In the sexual life cycle, a round structure called an antheridium buds from the male strain, and a similar structure called the ascogonium buds from the female strain. In a process called plasmogamy, the ascogonium and antheridium fuse to form a cell with multiple haploid nuclei. Mitosis and cell division result in the growth of many hyphae, which form a fruiting body called the ascocarp. The hyphae are dikaryotic, meaning they have two haploid nuclei. Asci form at the tips of these hyphae. In a process called karyogamy, the nuclei in the asci fuse to form a diploid (2n) zygote. The zygote undergoes meiosis without cell division, resulting in an ascus with four 1n nuclei arranged in a row. Each nucleus undergoes mitosis, resulting in eight ascospores, which are also arranged in a row at the tip of the hyphae. Dispersal and germination results in the growth of new mycelia.

Which of the following statements is true?

  1. A dikaryotic ascus that forms in the ascocarp undergoes karyogamy, meiosis, and mitosis to form viii ascospores.
  2. A diploid ascus that forms in the ascocarp undergoes karyogamy, meiosis, and mitosis to form eight ascospores.
  3. A haploid zygote that forms in the ascocarp undergoes karyogamy, meiosis, and mitosis to grade eight ascospores.
  4. A dikaryotic ascus that forms in the ascocarp undergoes plasmogamy, meiosis, and mitosis to form viii ascospores.

The bright field light micrograph shows ascospores being released from asci in the fungus Talaromyces flavus var. flavus. (credit: modification of work by Dr. Lucille Georg, CDC; scale-bar data from Matt Russell)


Micrograph shows asci, which appear as multiple, sphere-like shapes fused together into a structure about 7 microns across, and ascospores, which are small, light blue ovals about two microns wide by three microns long released from the asci.

Basidiomycota: The Club Fungi

The fungi in the Phylum Basidiomycota are easily recognizable under a light microscope by their lodge-shaped fruiting bodies called basidia (atypical, basidium), which are the swollen final cell of a hypha. The basidia, which are the reproductive organs of these fungi, are often contained within the familiar mushroom, commonly seen in fields after pelting, on the supermarket shelves, and growing on your lawn ([link]). These mushroom-producing basidiomyces are sometimes referred to as "gill fungi" because of the presence of gill-like structures on the underside of the cap. The "gills" are actually compacted hyphae on which the basidia are borne.

This group besides includes shelf fungus, which cling to the bark of trees like small shelves. In addition, the basidiomycota includes smuts and rusts, which are important plant pathogens; toadstools, and shelf fungi stacked on tree trunks. Most edible fungi belong to the Phylum Basidiomycota; however, some basidiomycetes produce deadly toxins. For example, Cryptococcus neoformans causes severe respiratory illness.

The fruiting bodies of a basidiomycete grade a ring in a meadow, normally called "fairy ring." The best-known fairy band fungus has the scientific name Marasmius oreades. The torso of this fungus, its mycelium, is surreptitious and grows outward in a circle. As it grows, the mycelium depletes the soil of nitrogen, causing the mycelia to grow away from the center and leading to the "fairy ring" of fruiting bodies where at that place is adequate soil nitrogen. (Credit: "Cropcircles"/Wikipedia Commons)]


Photo shows toadstools growing in a ring on a lawn.

The lifecycle of basidiomycetes includes alternation of generations ([link]). Spores are by and large produced through sexual reproduction, rather than asexual reproduction. The club-shaped basidium carries spores called basidiospores. In the basidium, nuclei of two different mating strains fuse (karyogamy), giving rise to a diploid zygote that then undergoes meiosis. The haploid nuclei migrate into basidiospores, which germinate and generate monokaryotic hyphae. The mycelium that results is called a main mycelium. Mycelia of different mating strains tin can combine and produce a secondary mycelium that contains haploid nuclei of 2 unlike mating strains. This is the dikaryotic stage of the basidiomyces lifecyle and and it is the dominant phase. Eventually, the secondary mycelium generates a basidiocarp, which is a fruiting body that protrudes from the ground—this is what we think of as a mushroom. The basidiocarp bears the developing basidia on the gills nether its cap.

Art Connection

The lifecycle of a basidiomycete alternates generation with a prolonged stage in which two nuclei (dikaryon) are present in the hyphae.


The life cycle of basidiomycetes, better known as mushrooms, is shown. Basidiomycetes have a sexual life cycle that begins with the germination of 1n basidiospores into mycelia with plus and minus mating types. In a process called plasmogamy, the plus and minus mycelia form a dikaryotic mycelium. Under the right conditions, the dikaryotic mycelium grows into a basdiocarp, or mushroom. Gills on the underside of the mushroom cap contain cells called basidia. The basidia undergo karyogamy to form a 2n zygote. The zygote undergoes meiosis to form cells with four haploid (1n) nuclei. Cell division results in four basidiospores. Dispersal and germination of basidiospores ends the cycle.

Which of the post-obit statements is true?

  1. A basidium is the fruiting body of a mushroom-producing fungus, and it forms 4 basidiocarps.
  2. The effect of the plasmogamy stride is 4 basidiospores.
  3. Karyogamy results directly in the formation of mycelia.
  4. A basidiocarp is the fruiting trunk of a mushroom-producing fungus.

<!–<para> D–>

Asexual Ascomycota and Basidiomycota

Imperfect fungi—those that exercise not display a sexual phase—apply to exist classified in the class phylum Deuteromycota, , a nomenclature group no longer used in the present, always-developing classification of organisms. While Deuteromycota apply to be a classification group, recent moleclular analysis has shown that the members classified in this grouping belong to the Ascomycota or the Basidiomycota classifications. Since they do not possess the sexual structures that are used to classify other fungi, they are less well described in comparison to other members. Most members live on state, with a few aquatic exceptions. They form visible mycelia with a fuzzy appearance and are commonly known as mold.

Reproduction of the fungi in this group is strictly asexual and occurs by and large by production of asexual conidiospores ([link]). Some hyphae may recombine and grade heterokaryotic hyphae. Genetic recombination is known to accept place between the different nuclei.

Aspergillus niger is an asexually reproducing mucus (phylum Ascomycota) commonly plant as a food contaminant. The spherical structure in this calorie-free micrograph is a conidiophore. (credit: modification of work by Dr. Lucille Georg, CDC; scale-bar data from Matt Russell)


Micrograph shows Aspergillus mycelia, which look like long threads, and a spherical conidiophore about 40 microns across.

The fungi in this group have a large bear on on everyday homo life. The nutrient industry relies on them for ripening some cheeses. The blue veins in Roquefort cheese and the white crust on Camembert are the consequence of fungal growth. The antibiotic penicillin was originally discovered on an overgrown Petri plate, on which a colony of Penicillium fungi killed the bacterial growth surrounding information technology. Other fungi in this group crusade serious diseases, either directly as parasites (which infect both plants and humans), or every bit producers of potent toxic compounds, every bit seen in the aflatoxins released past fungi of the genus Aspergillus.

Glomeromycota

The Glomeromycota is a newly established phylum which comprises nearly 230 species that all live in close association with the roots of trees. Fossil records indicate that copse and their root symbionts share a long evolutionary history. Information technology appears that all members of this family grade arbuscular mycorrhizae: the hyphae collaborate with the root cells forming a mutually beneficial association where the plants supply the carbon source and energy in the form of carbohydrates to the fungus, and the mucus supplies essential minerals from the soil to the plant.

The glomeromycetes do not reproduce sexually and do not survive without the presence of plant roots. Although they accept coenocytic hyphae similar the zygomycetes, they do not form zygospores. DNA analysis shows that all glomeromycetes probably descended from a common antecedent, making them a monophyletic lineage.

Section Summary

Chytridiomycota (chytrids) are considered the virtually primitive grouping of fungi. They are by and large aquatic, and their gametes are the only fungal cells known to have flagella. They reproduce both sexually and asexually; the asexual spores are chosen zoospores. Zygomycota (conjugated fungi) produce non-septated hyphae with many nuclei. Their hyphae fuse during sexual reproduction to produce a zygospore in a zygosporangium. Ascomycota (sac fungi) form spores in sacs called asci during sexual reproduction. Asexual reproduction is their most common form of reproduction. Basidiomycota (social club fungi) produce showy fruiting bodies that contain basidia in the course of clubs. Spores are stored in the basidia. Most familiar mushrooms belong to this division. Fungi that have no known sexual wheel were classified in the course phylum Deuteromycota, which the present classification puts in the phyla Ascomycota and Basidiomycota. Glomeromycota grade tight associations (called mycorrhizae) with the roots of plants.

Art Connections

[link] Which of the following statements is true?

  1. A dikaryotic ascus that forms in the ascocarp undergoes karyogamy, meiosis, and mitosis to class viii ascospores.
  2. A diploid ascus that forms in the ascocarp undergoes karyogamy, meiosis, and mitosis to form eight ascospores.
  3. A haploid zygote that forms in the ascocarp undergoes karyogamy, meiosis, and mitosis to course viii ascospores.
  4. A dikaryotic ascus that forms in the ascocarp undergoes plasmogamy, meiosis, and mitosis to form 8 ascospores.

[link] A

[link] Which of the post-obit statements is truthful?

  1. A basidium is the fruiting body of a mushroom-producing fungus, and it forms iv basidiocarps.
  2. The outcome of the plasmogamy step is four basidiospores.
  3. Karyogamy results direct in the formation of mycelia.
  4. A basidiocarp is the fruiting body of a mushroom-producing fungus.

[link] D

Review Questions

The most primitive phylum of fungi is the ________.

  1. Chytridiomycota
  2. Zygomycota
  3. Glomeromycota
  4. Ascomycota

A

Members of which phylum produce a club-shaped structure that contains spores?

  1. Chytridiomycota
  2. Basidiomycota
  3. Glomeromycota
  4. Ascomycota

B

Members of which phylum establish a successful symbiotic relationship with the roots of trees?

  1. Ascomycota
  2. Deuteromycota
  3. Basidiomycota
  4. Glomeromycota

D

The fungi that do not reproduce sexually use to be classified every bit ________.

  1. Ascomycota
  2. Deuteromycota
  3. Basidiomycota
  4. Glomeromycota

B

Gratuitous Response

What is the reward for a basidiomycete to produce a showy and fleshy fruiting body?

By ingesting spores and disseminating them in the environment as waste matter, animals act as agents of dispersal. The benefit to the fungus outweighs the toll of producing fleshy fruiting bodies.

For each of the iv groups of perfect fungi (Chytridiomycota, Zygomycota,
Ascomycota, and Basidiomycota), compare the trunk structure and features, and provide an instance.

Chytridiomycota (Chytrids) may accept a unicellular or multicellular body structure; some are aquatic with motile spores with flagella; an example is the Allomyces. Zygomycota (conjugated fungi) accept a multicellular body structure; features include zygospores and presence in soil; examples are staff of life and fruit molds. Ascomycota (sac fungi) may accept unicellular or multicellular body structure; a feature is sexual spores in sacs (asci); examples include the yeasts used in breadstuff, wine, and beer production. Basidiomycota (social club fungi) accept multicellular bodies; features includes sexual spores in the basidiocarp (mushroom) and that they are mostly decomposers; mushroom-producing fungi are an example.

Glossary

Arbuscular mycorrhizae
mycorrhizae usually involving Glomeromycetes in which the fungal hyphae penetrate the cell walls of the plant root cells (but not the cell membranes)
ascocarp
fruiting torso of ascomycetes
Ascomycota
(also, sac fungi) phylum of fungi that shop spores in a sac called ascus
basidiocarp
fruiting body that protrudes from the footing and bears the basidia
Basidiomycota
(also, club fungi) phylum of fungi that produce gild-shaped structures (basidia) that contain spores
basidium
club-shaped fruiting torso of basidiomycetes
Chytridiomycota
(also, chytrids) archaic phylum of fungi that alive in water and produce gametes with flagella
Deuteromycota
former form phylum of fungi that do not have a known sexual reproductive cycle (soon members of 2 phyla: Ascomycota and Basidiomycota)
Ectomycorrhizae
mycorrhizae in which the fungal hyphae practise not penetrate the root cells of the plant
Glomeromycota
phylum of fungi that class symbiotic relationships with the roots of trees
mold
tangle of visible mycelia with a fuzzy appearance
Zygomycota
(too, conjugated fungi) phylum of fungi that grade a zygote contained in a zygospore
zygospore
structure with thick cell wall that contains the zygote in zygomycetes

Source: http://pressbooks-dev.oer.hawaii.edu/biology/chapter/classifications-of-fungi/

Posted by: childressinks1998.blogspot.com

0 Response to "Which Of The Comparisons Of Fungal And Animal Nutrition Is Correct?"

Post a Comment

Subscribe to: Post Comments (Atom)

Iklan Atas Artikel

Iklan Tengah Artikel 1

Iklan Tengah Artikel 2

Iklan Bawah Artikel