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Transcript of Fungi
All fungi are eukaryotic and heterotrophic.
Almost all fungal cells have cell walls made of chitin. This substance gives strength to the cell wall. It is also what makes up insects exoskeletons.
A very small percentage of fungal cells have cell walls composed of cellulose.
The cells contain a membrane bound nucleus and membrane bound organelles.
Most cells are haploid and elongated, thread-like structures.
Cells have mitochandria, golgi apparatus, and endoplasmic reticulum.
They don't have chloroplasts since they are non photosynthetic.
The organisms can be either unicellular or multicellular.
Unicellular Fungi Structure
Unicellular fungi are either individual oval or cylindrical cells.
Multicellular Fungi Structure
Most fungi are multicellular and are very diverse structurally.
Most fungus is made up of fine filaments called hyphae which are the basic structural units. In mushrooms, they're packed tightly and are difficult to see as seperate strands.
Myphae are often seperated by walls called septa which have holes to allow materials to pass through.
Fungi feed by secreting digestive enzymes on food and then absorbing the nutrients through their cell membranes (extracellular digestion).
Most get their food from dead organic matter. These organisms are called saprophytes.
Fungi that receive their food from living organisms are called parasites.
There are four ways to classify fungi based of the way they obtain nutrients.
These are fungi that absorb nutrients from living cells of a host organism
Most of the time, they live inside the host
When the host dies, the fruiting bodies of the fungus produce new spores
Predatory fungi have mycelia that are specialized structures for trapping prey.
They live in soil.
Example: Arthrobotrys trap nemotodes that live in the soil with rings in its hyphae.
These fungi have partnerships with other orgaisims - usually plants or protists.
Most of the time, they cover the roots of plants which increases the surface area available for the absorption of nutrients and the fungus receives sugar from the plant.
Organisms which are commonly known as decomposers.
The mycelia absorb nutrients from dead or decaying matter.
They have a big role in recycling the nutrients in ecosystems.
The name comes from the word "saprobe" which is an organism that feeds on dead organisms or organic wastes.
Fungi do not have a complex respiratory system like animals, instead they acquire gases through diffusion.
Fungi exchange gases with soil rather than with the atmosphere
Soil has microscopic pockets of air between the mineral particles, water, and organic matter.
The hyphae of the fungi grow into these spaces to absorb oxygen from them by diffusing it through the cell membrane. At the same time, carbon dioxide is diffused from inside the cell, through the cell membrane, and into the cells exterior environment.
There are three main types of asexual reproduction.
Spores are produced by one parent cell through mitosis which means they are genetically identical to their parent cells.
The fruiting bodies produce trillions of single celled spores which get carried by wind, water, or other organisms. Some will land in an area that can support them and will grow into a visible organism while most will never form new individuals.
The huge number released helps increase their chance for survival and dispersal
There are many different types of spores including:
The type of asexual reproduction when a piece of mycelium separates/breaks off and forms a new, separate mycelium which grows into a new organism.
The last main type of asexual reproduction.
It's when a smaller cell is developing while attached to a parent cell.
This happens when the cell nucleus divides by mitosis and a small part of the cell containing one of the nuclei becomes distinguishably separate from the rest of the cell, forming a bulge.
The smaller cell is eventually pinched off to produce a new individual.
Some unicellular fungi, like yeasts, use budding to reproduce.
The reproduction of fungi involves both sexual and asexual methods.
Unicellular or multicellular spores released directly from the tip or side of a hypha.
Spores produced in a sporangium at the end of a hypha.
Sexual reproduction allows for genetic variation in the fungi populations.
It normally occurs when responding to adverse environmental conditions.
The first stage where two haploid cells fuse.
They form a single, dikaryotic cell. The two haploid nuclei coexist in a single cell.
Plasmogamy means "union of cytoplasm"
When the haploid nuclei fuse to form a diploid cell.
The process of meiosis occurs in the gametangia organs.
This is when the gametes of different mating types (male and female structures) are generated.
Once this happens, spores are dispersed into the environment
This is when structures grow from the spores.
For example, when the hyphae grow from spores to produce a multicellular mycelium.
The type of mycelium has an affect on how the fungi sexually reproduce.
There are two types of mycelia.
Homothallic mycelium is when both mating types (male and female reproductive structures) are present in the same mycelium.
It's self fertile.
Heterothallic mycelium requires two different, but compatible, mycelia to be able to reproduce sexually
Two different individuals must contribute to form a zygote
There are four main stages of sexual reproduction.
Some fungi exchange gas based on their environment.
For example, yeast performs respiration based on when oxygen is present.
When oxygen is present, it performs aerobic respiration. It absorbs oxygen through tiny pores
When there is no oxygen available, it performs anaerobic respiration. It absorbs the nutrients it can, causing fermentation in the process. This is the breakdown of glucose without oxygen. Enzymes for this process are found in the cytoplasm.
But there are some exceptions to this process.
Impacts of Fungi
Fungi have an essential role in the decomposition of organic matter and in nutrient cycling and exchange.
When they decompose organisms, they return nutrients to the soil for other organisms to use.
Since the 1940's, different types of fungi have been used for the production of antibiotics and are now the basis of many important medicines.
For example, penicillin is made from a common fungus called
. It has reduced formerly serious illnesses to minor burdens.
Some cancer drugs and anti-rejection drugs (used in organ transplant patients) are made from fungi as well.
Fungi, such as mushrooms and truffles, are also used as food sources for humans and other organisms.
They are also used as leaving agents in bread (Ex. yeast).
As well, they're used in the production of food products like wine, beer, soy sauce, and cheese.
Mutualistic fungi benefit other organisms and help them survive.
For example, if a mutualistic fungus didn't cover the roots of a plant to increase the surface area available for the absorption of nutrients, the plant may not be able to survive or be as healthy as it is with the fungus.
Some fungi are pathogenic or cause infections in animals like ringworm or athletes foot.
Fungi that parasitise insects can be very useful in controlling insect pests of crops.
The spores are sprayed on the crop pests and the fungus infests them, saving the crops.
This method is cheaper and much less damaging to the environment than chemical pesticides.
They also cause disease in crops. Some fungi are parasites of plants and most crops are extremely susceptible to fungal attack.
Spore production and dispersal is very efficient which makes attacking many plants of the same species in one field very easy.
Fungal diseases can result in the loss of an entire crop if they aren't treated with antifungal agents.
Fungi can cause food to spoil by breaking it down, causing it to be inedible.
They normally break down moist food as opposed to dry food.
This is a major problem when storing big amounts of food together.
Although the fact that fungi decompose organisms is an advantage, there is another side to it that is a disadvantage.
Not only will fungi decompose and spoil food as previously mentioned, it can decompose everyday resources like cloth and lumber.
For example, mold can grow in your house, making the air dangerous to breathe and you would have to tear out all of it, completely renovating your house.
Cases of fungus invading peoples' buildings are not uncommon.
Fungi don't have a heart or blood vessels like humans do for circulation.
Instead, circulation comes from the masses of connecting hyphae.
The hyphae grow and expand into the soil where nutrients are. They assist in nutrient exchange and water absorption for the organism. They branch throughout the whole organism and carry and supply the nutrients and water to the entire fungi.
As you can see, the pros of fungi clearly out weigh the cons. Not only are there more of them, but the advantages have much more of an impact on humans and every other organism as well.
There are five major fungi phyla:
1. Phylum Deuteromycota
2. Phylum Chytridomycota
3. Phylum Zygomycota
4. Phylum Ascomycota
5. Phylum Basidiomycota
Taxonomists largely classify fungi based on the method of reproduction (sexual, asexual, or both), the structure of the fruiting body, and more recently, molecular data.
This phylum is also called Fungi Imperfecti.
These organisms reproduce asexually, mainly by the production of conidiospores.
This is a very diverse group of fungi. Taxonomists aren't 100% certain they are closely related because they don't contain the sexual structures that are used to compare other fungi.
Most of these organisms live on land and form visible mycelia. This mycelia is the fuzzy substance called mold.
Fungi in this phylum are the simplest and most primitive.
The evolutionary record shows that the first distinguishable chytrids appeared over 500 million years ago during the late pre-Cambrian period.
Most are aquatic species, living in freshwater or marine ecosystems. Their habitats are actually very similar to those of protists.
Some chytrids are parasites (living off of plants, insects, or amphibians) while others are saprobes (living on decaying plants or insects).
Some of these fungi cause disease in amphibians leading to a decline in population or even extinction.
The organisms in this phylum are also called chytrids.
Most chytrids are unicellular.
Their cell walls are made of chitin, however, the cell walls of one group of chytrids are made of both chitin and cellulose.
They reproduce both sexually and asexually.
Their spores are the only fungal cells that have flagella.
These fungi reproduce both asexually and sexually.
But they usually reproduce asexually. Their nuclei are haploid when the fungi is in the vegetative stage.
On the rare occasion they reproduce sexually, they produce zygospores. Zygospores are diploid structures that develop after two haploid hyphae of opposite types combine and fuse their nuclei together. Then, a thick wall develops around the zygospore, keeping it from drying out. It remains dormant until conditions allow for growth/germination. Lastly, it absorbs water and undergoes meiosis, producing haploid spores which will turn into a new organism
The production of zygospores by the organisms in this phylum during sexual reproduction is why they are also called zygospore fungi.
The fungi in this phylum only make up about 1% of all fungi.
They are multicellular
They include common molds found on bread and fruits, but there are many other species included as well that go unnoticed.
This phylum includes fungi that are terrestrial, living in soil and decaying plants and animals.
This is the largest of all the 5 phyla.
The organisms in this phylum are also called sac fungi.
It includes the mildews that grow on leaves, truffles and morels used in dinners, and yeasts.
Most of these fungi obtain nutrients by breaking down materials in wood and bone.
Others are parasites of plants. These parasitic fungi can cause leaf curl, chestnut blight, or Dutch elm disease.
Almost all of these fungi reproduce sexually.
They develop asci, which are small, finger-like structures where haploid spores are developed and contained, during sexual production.
Asci means sac which is where their alternative name "sac fungi" comes from.
Yeasts reproduce differently.
They use the asexual method of budding.
Basidiomycotes are also called club fungi.
They include mushrooms, puffballs and stinkhorns that grow on the forest floor.
Some club fungi are parasites of plants and cause damage to crops.
They reproduce sexually.
Apart of their fruiting bodies is their cap which, on their underside, have gills.
These gills are compact hyphae which old the basidia
The basidia are club-shaped hyphae which release spores called basidiospores.
A fungi that causes black mold on some fruits and vegetables
A common contaminant of food.
It is found in soil and indoor environments.
It is rare for it to cause severe disease in humans, but it is possible for a human to contract a lung disease called aspergillosis.
It is the most common source of fungal ear infections in humans which can cause pain, temporary hearing loss, or damage to the ear canal.
A filamentous fungus that is commonly used in East Asian cuisines to ferment soybeans.
It is also used to saccharify rice, other grains, and potatoes to make alcoholic beverages and for the production of rice vinegars.
They are very useful in what they are used for because they have very quick mycelial growth, a pleasant fragrance, and very little colour.
A fungus that causes potato wart disease or black scab.
Favourable conditions for this organism are warm and humid temperatures.
It can survive up to 50cm below ground in the soil.
It produces a thick walled structure called a winter sporangium.
It originates in South America but is now distributed worldwide where potatoes are cultivated.
This organism causes a disease called chytridiomycosis in amphibians.
The fungus grows on amphibian skin and produces aquatic zoospores.
It was discovered in 1998 and a few years later, devastated amphibian populations around the world. It drove many species toward extinction.
Its habitats vary from lowland forests to mountain tops.
It's optimal temperatures (in degrees Celsius ) to grow in are between 17 and 25 but can grow in temperatures as low as 4 degrees Celsius.
Sometimes, this fungus is a non-lethal parasite or is even saprobic.
This fungus is a plant pathogen that infects strawberries.
Commonly called black bread mold.
The fatest growing of its phylum.
It is found all over the world.
Depends on starch, sugar, and a moist environment which makes bread the perfect host.
It takes the breads' nutrients which causes damage to the surface where it lives.
It's also used in medicines like birth control pills and people who have hormone deficiences.
However, it can also be pathogenic, causing infections in humans.
Commonly known as bonnet mold.
It is a parasitic mold that grows on the cap of mushrooms. They grow reproductive stalks called sporangiophores which contain small structures that contain the spores called sporangia.
They have a very distinct look.
It is a homothallic fungus, therefore it can reproduce sexually from one spore.
A fungal plant pathogen that was discovered in 1886.
It's known to cause allergic reactions in humans.
It's worldwide primarily as a soil fungus but it is also found on cheese, camembert, plant remains, grains, vegetables, and nuts.
It is used to treat blood disorders in humans.
A filamentous fungus generally found in soil and plant material in subtropical and Mediterranean areas.
It has also been found in animal material, cheese, and Brazil nuts.
It is pathogenic, causing infections to some hosts.
It is found widespread all over the world in humid environments, usually in soil or dead plant material. It's optimal soil has a pH between 3.0 and 8.0 and is 30cm-40cm deep.
It can also survive in the air, underground, or on humans and animals.
A pathogen known to cause pulmonary, central nervous system, rhinocerebral, and skin infections in animals and humans. Humans are much more likely to contract these infections if they have weakened immune systems due to diseases (HIV, diabetes, blood cancers). They can be fatal.
This is a species of fungi that commonly grows on herbivore feces.
Unknowingly, herbivores eat this fungus at the beginning of its life cycle as black sporangium. The sporangium survives the passage trhough the digestive tract and is excreted along with the animals feces. Once it's outside the animal, the fungus germinates and the mycelia grow within the dung.
This organism is a decomposer, feeding on and breaking down non-living organic matter, and because of this, plays a cruicial role in ecosystems.
Has many common names such as Candlestick Fungus, Carbon Antlers, or Dead Man's Fingers.
It is an inedible fungus.
This fungus is characterized by long black branches with whitened tips that typically grow in clusters straight out from the forest floor.
It can cause root rot in gooseberry and hawthorn plants.
It contains a carbohydrate-binding protein with a unique sugar specifity and has shown to have anti-tumor effects in studies.
This fungus can be in temperate and tropical regions and salted food products. But it's mostly found in indoor environments, especially waterdamaged or damp buildings.
It is very important to humans as it is used industrially to produce penicillin. It's also used to treat pulp mill waste.
This fungus is found on tree trunks or other tree surfaces.
It enters through wounds or cracks in the tree, grows under the bark, and eventually kills the areas around it.
It produces yellow or orange spores which make the affected areas of the tree turn orange.
It is the main cause of chestnust blight. This is a disease of the American chestnut tree that caused a quick, widespread die-off of this species in the eastern United States in the early 1900's.
This is a black mold that requires lots of moisture to grow. Because of this, it is most often found in buildings that are damp or water damaged. They are also sometimes found in soil and grain.
It is a mycotoxin produces that can cuse animal and human mycotoxicosis. It has become a serious problem in buildings and homes.
This is a saprobial fungus, involved in the processing of dead or decayed organic matter.
It commonly grows on cereal grains, legumes, and tree nuts.
It is pathogenic.
infections infect many important agriculture crops. They can occur preharvest, while the hosts are still in the field, but typically won't show symptoms until postharvest storage and/or transportation. If these products are consumed, the mycotoxins that are produced are toxic to mammals.
This fungus can also cause aspergillosis to humans with an impaired immune system.
It also causes ear rot in corn and yellow mold in peanuts.
A fungal plant pathogen that causes black knot on trees.
It produces a rough, black substance that encircles the branches of trees. It actually provides habitats for insects. However, eventually the branch or the whole tree will die if left untreated.
It occurs only on the wood part of the tree, not on the leaves. Normally it occurs only on twigs and branches but occasionally it can spread to larger limbs or even the trunk.
This fungus is well contained now. However, it has been a problem in the past, being one of the most destructive diseases to the cherry, apricot, and plum trees in North America in the late 19th century.
This is a unicellular yeast that can live in both plants and animals.
This fungus commonly grows on old bird droppings
It can cause serious infections that can be fatal. Most of the infections caused by this fungus affect the lungs as they are contracted by inhaling airborne basidiospores. However, contracting fungal meningitis is also a possibility.
This is a saprobic fungus that is commonly called collared earthstar or the triple earthstar.
It is found in the detritus of leaf litter and forests all over the world
Their immature fruiting bodies are spherical and buried into the ground, resembling puffballs. As it matures, the outer layers of tissue splits into four to eight pointed segments that lift the spore sac out of the ground.
This fungus is not poisonous, however, they are tough and fibrous which makes them practically inedible.
This fungus is commonly known as the giant puffball.
They can be anywhere from 10cm to 70cm in diameter.
It is commonly found in meadows, fields, and deciduous forests worldwide in late summer and autumn.
Puffballs are edible when they are immature and taste very similar to tofu or melted cheese. However, if spores have begun to form, it can cause digestive discomfort.
It doesn't have a cap with spore bearing gills. Instead, the spores are produced internally and create what's alled a gleba in the center of the fruiting body. Once it is mature, the fruiting body bursts and releases the spores.
This fungus is commonly known as the lentil shanklet or the appleseed coincap.
It is found in Europe, North America, and Japan.
It is inedible.
It grows in dense clusters, living on the decomposing remains of other mushrooms and produce small fruiting bodies with caps up to 1 cm wide.
The colour of the cap changes according to the level of its hydration.
It is unknown whether this fungus is purely parasitic and needs the host mushrooms to live, or if it is saprobic.
This is an edible mushroom that grows in Europe and North America
When it is mature, it is known as a Portobello mushroom. It is one of the most commonly and widely consumed mushroom in the world.
Also known as ringworm.
It is a fungal infection of the top layer of skin, that mostly occurs on the arms and legs but can occur on any part of the body.
It is very contagious and affects humans and pets. It can easily be treated by topical antifungal creams.
This is a pathogenic species is found on the skin surfaces of many animals.
It causes skin diseases in humans. The most common are dandruff and seborrhoeic dermatitis.
This fungus requires fat to grow, therefore it commonly found in areas of the body with many sebaceous glands (glands that secrete an oily/waxy matter to lubricate the skin and hair). These are located on the scalp, face, and upper part of the body.
This fungus is a species of yeast.
It is one of the most useful yeasts as it is used in wine making, brewing, and baking and has been since ancient times.
It exists as part of the thin white film on some skins of dark, mature fruits such as grapes and plums and also in the waxes of the cuticle (the epidermis of leaves).
This species of fungi is a pathogen that affects flies and often results in death.
When a spore comes in contact with a fly, it penetrates the fly's exoskeleton and grows on its brain. The mycelia can grow into an area of the brain that controls behaviour and it can control what it does. The hyphae grow through the whole body of the fly and digest its organs, causing the fly to die in 5-7 days from when the fungus entered the fly's body.
This fungus is found in most temperate regions in the spring and autumn.
This species is most commonly known as the ugly milk cap.
The center of the mushroom is sunken inwards and its colour is similar to that of spoiled milk since it has collected lots of dirt and debris on the top of the cap, which is usually about 8cm-20cm.
It is found on many trees such as birch, pine, and spruce.
When this organism is cut into, latex, a milky fluid, comes out.
It is native to Europe and Siberia but has now been introduced to Australia and New Zealand.
This species of fungi is commonly called the dog stinkhorn. This is because of the odor it emits.
It is a small and thin woodland fungus with a dark tip which has a smell that attracts insects
It is mostly found growing in small groups in leaf litter, wood debris, or wooded roadsides during autumn and summer in Asia, Europe, and Eastern North America.
The mycelium is a net-like mass of branching hyphae which makes up most of the organism. It lives in the soil and on other nutritious substances such as living, dying, or dead wood or animal bodies. The mycelium is also the vegetative part of the organism.
The fruiting body is the part of the fungus that you see above the ground. It is the reproductive structure and produces airborne spores.
A mass release of spores from a puffball.
This is the sexual and asexual life cycles of fungi
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Jan. 11, 2015
The Armillaria solidipes is considered the largest
organism on Earth. It spreads over 2000 acres underground in soil in eastern Oregon. It is estimated
to be about 2400 years old!