Classification of Fungi | Biological Classification | Biology | Khan Academy
Summary
TLDRThis script explores the diverse kingdom of fungi, highlighting their widespread presence and unique characteristics. It delves into the classification of fungi, focusing on recent systems and discussing four major phyla: Chytridiomycota, Zygomycota, Ascomycota, and Basidiomycota. Each phylum's distinct reproductive methods, from the motile zoospores of Chytrids to the sexual conjugation of Zygomycetes, and the ascospores and basidiospores of Ascomycota and Basidiomycota, are explained. The script also touches on the importance of fungi in various industries and the dynamic nature of fungal taxonomy.
Takeaways
- 🌿 Fungi are incredibly widespread, existing in diverse environments including our homes, and can be found without even stepping outside.
- 🔬 Fungi classification has evolved significantly over time, with modern scientists using more advanced systems compared to older methods.
- 🌀 The phylum Chytridiomycota contains the simplest and most primitive fungi, characterized by their motile zoospores with flagella, unique among fungi.
- 🍞 Zygomycota, including the common bread mold Rhizopus stolonifer, reproduces both asexually through sporangiospores and sexually through a process called conjugation.
- 🍄 Ascomycetes, part of the phylum Ascomycota, are known for their sac-like ascus containing sexual spores called ascospores and are crucial in commercial applications like baking and brewing.
- 🍄 Basidiomycota, the phylum that includes mushrooms, is recognized by their club-shaped basidia which bear sexual spores known as basidiospores.
- 🍄 Sexual reproduction in fungi often involves complex processes like plasmogamy and karyogamy, leading to the formation of spores that can develop into new fungi.
- 🌱 Asexual reproduction in fungi is also common, with some phyla like Deuteromycetes lacking a known sexual phase in their life cycle.
- 🔍 The classification of fungi is dynamic and subject to change as new research and molecular analysis provide deeper insights into their evolutionary relationships.
- 🌟 Notable examples of fungi include edible mushrooms, truffles, and yeasts like Saccharomyces cerevisiae, which are used in various food and industrial processes.
Q & A
Where can you commonly find fungi?
-Fungi can be found in a variety of places, including greenish-black patches on old bread, in bottles marked with 'activated yeast,' growing on damp logs in gardens, and even in water bodies or wet soils.
How has the classification of fungi changed over time?
-The classification of fungi has changed dramatically over time. Scientists now refer to newer, more advanced systems of classification, which is what the video focuses on, rather than older systems.
What is the significance of the phylum Chytridiomycota?
-Chytridiomycota is significant because it houses the simplest and most primitive fungi. These fungi, known as chytrids, are often unicellular organisms found in water bodies or wet soils and are unique for their motile zoospores with flagella.
What is the common name for the fungus that grows on stale bread?
-The fungus that grows on stale bread is commonly known as 'common bread mold,' and it is scientifically referred to as Rhizopus stolonifer.
How do zygomycetes reproduce sexually?
-Zygomycetes reproduce sexually through a process called conjugation, where two compatible haploid hyphae extend towards each other, touch, and fuse to form a zygospore containing multiple diploid nuclei.
What is the function of an ascus in ascomycetes?
-In ascomycetes, an ascus is a sac-like structure that contains haploid sexual spores called ascospores. It is part of the ascocarp, which is a spore-bearing structure.
Why are ascomycetes important to humans?
-Ascomycetes are important to humans because they are used in various commercial processes such as baking, brewing, and fermenting wine. One example is yeast, which is used in baking and brewing.
What are basidiomycetes and how do they reproduce?
-Basidiomycetes, also known as club fungi, are characterized by their club-shaped spore-bearing structures called basidia. They reproduce sexually, with basidiospores being produced on the gills of mushrooms and released into the environment to germinate into new fungi.
Why are deuteromycetes not considered a true phylum?
-Deuteromycetes, also known as imperfect fungi, are not considered a true phylum because their members are more closely related to organisms from other phyla than to each other. For example, Aspergillus, once thought to be a deuteromycete, is now classified within the phylum Ascomycota.
What is the dynamic nature of fungi classification?
-Fungi classification is dynamic and ever-changing, as it is based on ongoing research and molecular analysis. This means that the classification systems can evolve, and what is considered accurate today might be revised in the future.
Outlines
🍄 Introduction to Fungi Diversity and Classification
The script begins by highlighting the ubiquity of fungi, which can be found in various environments, including in our homes. It emphasizes the diversity of fungi and how scientists classify them into different phyla based on unique features. The video aims to discuss the major phyla of the kingdom fungi, focusing on recent classification systems rather than older ones. The first phylum introduced is Sky tridiomycota, which contains the simplest and most primitive fungi. These are unicellular organisms typically found in water bodies or wet soils, characterized by their chitin cell walls and saprotrophic or parasitic nutrition. What sets them apart is their production of motile zoospores, which are unique among fungal spores due to their ability to move using a flagellum. A well-known example of a skytrid is the organism called aloe mysis.
🍞 Zygomycota: The Stale Bread Mold Fungi
The second paragraph delves into the phylum Zygomycota, exemplified by the common bread mold, Rhizopus stolonifer. This fungus reproduces asexually through sporangiospores, which form within a sporangium. However, under unfavorable conditions, zygomycetes switch to sexual reproduction. The sexual reproduction process involves the fusion of compatible haploid hyphae, leading to the formation of a zygospore containing multiple diploid nuclei. This zygospore undergoes meiosis, resulting in haploid spores. The process is termed conjugation, hence zygomycetes are also known as conjugated fungi. The paragraph also touches on the commercial importance of some zygomycetes, such as yeast used in baking, brewing, and winemaking.
🍄 Ascomycota: The Sac Fungi with Ascus and Ascospores
The third paragraph discusses the phylum Ascomycota, characterized by the presence of an ascus, a sac-like structure containing haploid sexual spores called ascospores. These fungi, also known as sac fungi, reproduce sexually through a process involving plasmogamy, karyogamy, and meiosis, resulting in the formation of ascospores within the ascus. The ascus is housed within a spore-bearing structure called an ascocarp. Ascomycetes are beneficial, especially in commercial applications, with yeast being a prime example used in various food processes. Other examples include truffles, morels, and Aspergillus, which, despite once being classified as a deuteromycete, is now recognized as an ascomycete due to molecular analysis.
🍄 Basidiomycota: The Club Fungi with Basidia
The final paragraph focuses on the phylum Basidiomycota, commonly known as club fungi due to their club-shaped spore-bearing structures called basidia. These basidia are found on the gills of mushrooms, which are part of the fruiting body known as the basidiocarp. Sexual reproduction in basidiomycetes involves the production of basidiospores within the basidia. Unlike other fungi, basidiomycetes primarily reproduce sexually, and the paragraph does not discuss asexual reproduction for this group. The phylum includes various types of fungi such as mushrooms, toadstools, shelf fungi, smuts, and rusts. The script concludes by acknowledging the dynamic nature of fungal classification, hinting at the possibility of further changes in the future.
Mindmap
Keywords
💡Fungi
💡Classification
💡Phylum
💡Chitin
💡Saprotrophic
💡Zoospores
💡Zygomycota
💡Ascomycetes
💡Basidiomycota
💡Deuteromycetes
💡Conjugation
Highlights
Fungi are widely distributed and can be found almost everywhere, including inside homes.
Fungi exhibit a high degree of diversity, each with unique features.
Fungi classification has evolved significantly over time.
Scientists now use more advanced systems for classifying fungi.
The phylum Chytridiomycota includes the simplest and most primitive fungi.
Chytrids are often unicellular and found in water bodies or wet soils.
Chytrids produce unique, motile zoospores with flagella.
Zoospores are the only motile fungal spores.
A well-known chytrid is Allomyces.
Zygomycota includes fungi like Rhizopus stolonifer, responsible for bread mold.
Zygomycotes reproduce sexually through a process called conjugation.
The zygospore is a thick-walled structure containing multiple diploid nuclei.
Ascomycetes are characterized by the presence of an ascus, a sac-like structure containing ascospores.
Ascospores are haploid sexual spores produced within the ascus.
Sac fungi, or Ascomycetes, include commercially important species like yeast.
Basidiomycota, or club fungi, are recognized by their club-shaped basidia.
Basidia are found on the gills of mushrooms and produce basidiospores.
Basidiomycetes include mushrooms, toadstools, and other fungi that form fruiting bodies.
Deuteromycetes, or imperfect fungi, do not show a sexual phase in their life cycle.
Deuteromycetes are not considered a true phylum as they are more closely related to other phyla.
Fungi classification is dynamic and subject to change with new research.
Transcripts
what if I tell you that fungi are so
widely distributed on our planet that
you can find them pretty much everywhere
yes really in fact you might not even
have to step out of your house in order
to see one the greenish black patches on
that two-week old bread fungi that
bottle on the kitchen shelf which is
marked activated East fungi the
mushrooms growing on those damp logs in
your garden you know it fungi and you've
probably noticed by now that they're
wildly diverse too each of these fungi
has its own set of unique features and
using these features scientists were
able to classify them over the years but
the thing is that in all this time fungi
classification has changed dramatically
many scientists nowadays refer to newer
more advanced systems of classification
so in this video that's what we're gonna
do as well we're gonna talk about some
of the major phyla in kingdom fungi and
their distinct characteristics and while
we are doing so we'll try to stick to
the more recent versions of fungi
classification rather than the older
ones so let's get into it
the first phylum we have over here is
Sky tridiomycota now I'll be honest I
didn't get that pronunciation right the
first time and neither did I know that
this phylum existed up until I actually
started looking into it and it turns out
that this phylum houses all of the
simplest most primitive fungi to ever
exist on our planet most of these
skytrids that's what you call the
members of this phylum most of this guy
these kitrids are unicellular organisms
that are often found in water bodies or
wet soils and like every other fungi
they also have chitinus cell walls and
Exhibits saprotrophic or parasitic
nutrition however what truly sets
skytrids apart from the rest of the
fungi are there a motile zeuspores the
spores that the kitrids produce they are
called zoos Sports and each of them come
equipped with a flagellum like this and
using this flagellum the Zeus pore can
actively move around or swim around all
on their own and mind you no other
fungal spore can do this they are the
only more tile spores to exist and
kitrids are the ones that can produce
these pores a very famous example or a
very famous kitrid is this organism
right here which is called aloe
my sis
next up we have the zygomyces members of
the phylum zygomycota and we've already
come across a zygomycin before remember
the stale moldy bread at the beginning
of this video well the fungus that grows
on stale bread it's called the common
bread mold and that is scientifically
called rhizopus tolonifer which is this
fungus right over here so if you take a
piece of that moldy bread and place it
under a microscope this is what you're
gonna see now the most fascinating thing
about zygomycetes is how they reproduce
sexually normally they reproduce
asexually with the help of something
called sporangiospores which are these
pores that are formed inside a structure
called a sporangium you can actually see
a sporangium right over here so this
bulb-like structure here this is the
sporangium
sporangium and inside of this is where
the sporangiospores are formed and
sporangiospores are the way to go
normally when things are fine but when
the environmental conditions become
unfavorable the fungus or these fungi
they resort to sexual reproduction that
is when sexual reproduction takes place
so let's take a look at this process so
during sexual reproduction what really
happens is that two compatible haploid
hyphae will start extending towards each
other till their tips touch kind of like
this and the minute the tip touches what
happens is that it kind of walls off a
section or a portion of this tip so
let's say it starts to wall off
somewhere here by building by forming
something called a septum which you can
think of it like a partition so this is
a septum
I'll just write it down over here so it
starts to wall off a certain section by
forming this septum and when this once
this partition is done or this Walling
off is done what will happen is that
everything in this portion right over
here will fuse together even the nuclei
now over here I have you can see that
there are only two two nuclei but
usually what happens like this is just
an image that I've drawn but uh in real
life like in nature when this fusing
happens there are many haploid nuclei
which are present in this area depending
on where this wall of thing happens
where the partition begins to appear So
based on where the partition appears
many haploid nuclei are present in
between or they are trapped in between
this uh section of the extension or the
tips basically so now what happens these
nuclei they will also fuse along with
the tips so after all of the fusion what
really happens what we get at the end of
that is this zygospore so this uh
haploid nuclei will fuse with this
haploid nuclei and give us this purple
one and again the same thing happens
with these two nuclei and we have two
basically uh diploid nuclei because the
haploid nuclei diffused right
so in the end we finally have a
zygospore which contains multiple
diploid nuclei now what happens after
this this zygospore will eventually
undergo meiosis and because of meiosis
What will happen this diploid nuclei
will become haploid nuclei
because of the meiosis that it happens
and each of these haploid nuclei each of
them separately will become a haploid
Spore and that is how uh through sexual
reproduction these haploid sexual spores
are formed
now this type of sexual reproduction
where the tips of the hyphy fuse
together to give the zygospore which
eventually gives us a haploid spores
this entire process is called
conjugation
and because of this because of this
conjugation process
zygomyces are often referred to as
conjugated fungi moving on the third
phylum on our list is ascomycota these
fungi are characterized by the presence
of something called acai or an Asus and
ascus is a sac-like structure which
contains the haploid sexual spores
called ascospores so these bead-like
structures that you can see inside this
sac-like thingy so these are the
ascospores inside the ascus and because
of the sac-like structure these fungi
are also called Sac fungi during sexual
reproduction
ascospores are formed inside thousands
of acai which in turn are found inside
of a Spore bearing structure called an
ASCO ascocarp now this so basically what
happens these ASCO spores they are
formed inside this ascus or inside the
acai and these acai is in turn found
inside something called the Asco
carp which is a Spore bearing structure
so inside this you will find the acai
and inside the acai you will find the
ASCO spores now the process of sexual
reproduction goes something like this
plasmogamy or Fusion of cytoplasm takes
place between two compatible haploid
cells and the fused cell enters a
diaryotic stage where the nuclei the
haploid nuclei they remain free
eventually these nuclei will also fuse
that means kariogami will take take
place and we will end up with a diploid
zygote inside the ascus this zygote will
further undergo meiosis and that will
give us the haploid ascospores these
ASCO spores are then released into the
environment and they end up germinating
at suitable places as for my seats also
undergo asexual reproduction by
producing asexual spores called kunidia
ascomyces are incredibly helpful to us
as well especially commercially and a
very important example of that is East
remember how we talked about uh dry
activated yeast being something that we
can find in our kitchen so we use East
to East in a variety of different things
like baking Brewing fermenting wine and
a bunch of different things so East is
an ascomycet which is extremely
important to us other examples of
ascomyces include truffles
uh then there are morals now these are
treated as Delicacies uh in different
parts of the world then there's also
aspergillus which is something you might
have heard of uh which is also uh an
ascomycet so these are some examples of
ascomyces the next major phylum is that
of the mushrooms AKA phylum basidio
mycota bacidio my seeds are easily
recognized by their club-shaped Spore
bearing structures called basedia now
there's only one structure here so this
will be a basidium that's the singular
form and because of this club shaped
basidium or basidia these uh fungi are
also called Club fungi now where will
you find this basidium or where will you
find all the biseria you will find them
on the gills of the mushroom so these
lines that you can see these are the
gills of the mushroom which are found on
the underside of the cap and this whole
protruding thing with the cap and
everything that is the fruiting body of
the mushroom called the basidio carp so
this entire thing let's pick a different
color we can't really see it in here so
this entire thing the protruding part of
the mushroom which is you know on the
top of the soil that we can see this is
the fruiting body which is called The
Busy do
carp
so that means the basidio carp Bears the
basidia on the gills now inside each
basidium beside your spores which are
these sexual spores by the way they are
produced and these basidio spores they
are produced in it's very similar to how
the ascospores are produced now once
these haploid basidio spores they are
formed they will be released into the
environment from the basidios carp and
then they will germinate into new fungi
now remember all mushrooms toadstools uh
then shelf fungi then smarts and rusts
all these types of fungi they belong to
phylum basidio mycota so they're all
basidiomyces now if you're wondering why
I didn't mention an asexual reproduction
here that's because usually all basidio
my seeds reproduce sexually so that's
why we are not discussing about the
asexual reproduction here
now these are just some of the major
phyla which has been included in kingdom
fungi now that that doesn't mean that
these are the only phyla by the way
there are other different phyla as well
for example glomeromycota is one such
phylum which is there in kingdom fungi
but one that we didn't really discuss
here uh this includes fungi which live
in very close association with uh plant
roots there's another group that you
might have heard of called
deuteromycetes aka the imperfect fungi
you know the fungi that do not show a
sexual phase in their reproductive
Cycles at all so those are the
deuteronomyces but the thing is that
deuteronomycota is not considered to be
a true phylum why because their members
are more close to closely related to
organisms from other phyla than each
other let me explain this to you with an
example aspergillus was earlier thought
to be a Deuter my seat but after a lot
of research and a lot of studies and
molecular analysis they finally found
out that aspergillus is more closely
related to ascomyces rather than
deuteronomyces so that's a completely
different phylum right ascomycota in
fact we we literally wrote down
aspergillus in the lesson today under
ascomycota so that's how aspergillus was
moved from deuteromycota to ascomycota
and that is why ASCO um that is why
deuteronomycota or deuteronomyces they
are not considered to be a true uh a
true member or a true phylum for that
matter so you see fungi classification
is an ever-changing Ever improving
ordeal it's not set in stone who knows
that maybe a few decades from now will
have a completely new system of
classification for all of these fungi it
is that dynamic
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