What is Fungus?
The kingdom Fungi, the
plural of fungus, are eukaryotic and heterotrophic organisms, capable of
absorbing organic carbon. They are essentially aerobic and include yeasts,
molds, and mushrooms.
Yeasts are unicellular
microscopic organisms which reproduce vegetatively by budding. Molds are
microscopic as well and are characterized by the presence of multicellular
hyphae forming a mycelium. Mushrooms, on the other side, present a macroscopic
sexual organ, the fruiting body where the sexual spores are produced.
A number of fungi
species are dimorphic and are capable of growing as yeasts or molds according
to the temperature or CO2 concentration. An example is Blastomyces dermatitidis
which can exist as both mold and yeast.
Fungi absorb their
nutrients through their cell wall following the release of specific enzymes
which digest organic macromolecules in the extracellular environment.
The digested molecules
then cross by diffusion through the fungal cellular envelope. Fungi are
saprophytes when the carbon originates from nonliving substrates and parasites
or commensal when the source of carbon is a living organism.
Reproduction in fungi
occurs by the production of spores which can be sexual or asexual. Sexual
reproduction involves the fusion of two haploid nuclei. This is followed by a
meiotic division of the nucleus.
During asexual
reproduction, asexual spores called sporangiospores are formed and divide
subsequently by mitosis.
Fungi are classified
based on their reproductive system: sexual, asexual, or as in some cases a
combination of both. Anamorphs constitute asexual reproductive structures, and
teleomorphs constitute the sexual reproductive structures. The term holomorph
is used to refer to the complete fungus with its anamorph and its teleomorph
structures.
What is Mold
Molds are a microscopic
type of fungi, which unlike the unicellular microscopic yeasts or the
macroscopic multicellular mushrooms, are characterized by the presence of
multicellular filaments called hyphae. The network formed by the hyphae
constitute the mycelium which is visible to the naked eye.
Hyphae grow by apical
elongation, a process involving the fusion of vesicles with the plasma membrane
at the apex, the consecutive digestion of the membrane, and the formation of a
new cell wall.
Molds can reproduce
sexually by forming zygospores which result from the fusion of two haploid
cells. When the environmental conditions are favorable, a zygospore undergoes
meiosis, the cellular division which results in two new haploid cells different
than the parent cell.
Molds can also
reproduce asexually. In this case, sporangiospores are released from special
hyphae called sporangiophores. Sporangiospores are diploid cells that undergo
mitosis producing new cells that are identical to the parent cell.
Difference between Mold
and Fungus
Definition of Mold and
Fungus
Fungi is a kingdom
comprising a large number of species which are eukaryotic and heterotrophic
organisms. It includes yeasts, molds, and mushrooms.
Molds are a group of
fungi, which are specifically multicellular microscopic organisms characterized
by the presence of multicellular filaments, the hyphae.
Morphology of Mold and
Fungus
Fungi can exist as
unicellular microscopic organisms called yeasts, as multicellular microscopic
molds with hyphae, or as macroscopic mushrooms with a visible sexual organ, the
fruiting body.
Some specific fungi can
also be dimorphic, present as both molds and yeasts, switching between the two
forms according to the environmental conditions such as temperature or CO2
concentration.
Molds, on the other
hand, are multicellular microscopic fungi, typically characterized by the
presence of hyphae filaments. The aggregation of the hyphae as a network
constitute the mycelium, visible to the eye.
Physiology of Mold and
Fungus
All fungi including
molds are essentially heterotrophic and aerobic organisms, with only some yeast
species being anaerobic.
They are both able to
absorb organic carbon from the environment through external digestion.
Catalytic enzymes are secreted and released into the extracellular environment
where macromolecules such as sugar, lipids, and proteins are therefore
digested. The resulting small molecules are then absorbed by diffusion into the
fungi cells.
Fungi and molds are
called saprophytes when the carbon originates from nonliving substrates and
parasites or commensal when the source of carbon is a living organism.
Reproduction of Mold
and Fungus
Fungi such as yeasts
and molds alike reproduce by the production of spores which can be sexual or
asexual. Sexual reproduction involves the fusion of two haploid nuclei followed
by the meiotic division of nucleus and resulting in two cells which are
different from the parent cell.
Asexual reproduction
occurs when diploid spores are formed and divide subsequently by mitosis,
producing two diploid cells identical to the parent cell.
Classification of Mold
and Fungus
All fungi including
molds are classified based on their reproductive structures. They are called
anamorphs when they reproduce asexually, teleomorphs when they present sexual
reproductive structures.
The fungus and mold is
a holomorph referring to both its asexual and sexual structures.
Mold versus Fungus:
Comparion Chart
Summary of Mold and
Fungus
Molds are a group of
microorganisms belonging to the kingdom of Fungi, which comprises as well
yeasts and mushrooms.
The main difference
between molds and other fungal species resides in their morphology. Molds are
multicellular microscopic organisms characterized by the presence of filaments
called hyphae, while yeasts are unicellular microorganisms, and mushrooms
present a macroscopic fruiting body producing spores.
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