Phylum refers to their reproductive sexual mechanism, as it

Phylum Zygomycota clusters more than 1100 different species, mostly
saprotrophic soil fungi, who exploits nutrients by decomposing waste products,
such as rotten fruit. Their name, refers to their reproductive sexual
mechanism, as it forms a structure called zygosporangium, arising from the
conjugation between two compatible hyphae, with each hyphae stemming from a separate
organism.  After conjugation, a cell wall
is formed behind the fusing hyphae, which at this point are called gametangia.
Next to this, the wall separating the two hyphae is broken down, leading to
fusion of both hyphae’s cell components into one organism, except their nuclei,
which are still separate entities. Following this, their nuclei fuse and the
walls around the zygosporangium grows even harder and thicker than before – this
converts the sporangium to a zygospore. After a long resting period, meiosis occurs,
and the fused nuclei are divided into two separate recombinant nuclei.  These are then later integrated and released
as meiospores. Most Zygomycota are harmless to humans, although a few are
pathological causing a disease called mucormycose,
which arises when spores are inhaled from dusty environments. 

Fungi in the third
phyla, phylum Ascomycota, are the
most abundant phylum as more than 65.000 species belong here. Their trademark
is their structural component, the ascus, which is a sac-like unit, harboring
eight ascospores, in which sexual and asexual reproduction occurs. The formation
of this component arises when a spore lands on a suitable substrate, after
which a haploid mycelium is formed. From this, asexual structures can be
produced, or sexual structures, gametangia, can be formed. The female sexual
structure is called ascogonium, while the male sexual structure is an
antheridium.  Fusing of sexual structures
leads to formation of one organism with two separate nuclei, this is called an
ascogonius hypha. Fusing of nuclei, takes place at the tip of this hyphae,
creating a diploid ascus, who undergoes meiosis and thus produces 4 recombinant
haploid nuclei. Followed by a round of mitosis eight ascospores are formed,
which can then be released and the cycle repeats. Due to the sheer amount of
species, phylum Ascomycota, exert both a positive and negative effect on the
human condition. Beneficial species such as Penicillium
notatum and Saccharomyces cerevisiae
contribute to our health and or ability to produce beverages, while malign
effects are seen by species of the Aspergillus genus who can cause a respiratory
disease, decay food, synthetize carcinogenic toxins in nuts etc. The
Aspergillus genus will be investigated extensively later in this paper. 

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now