Fungi C. Shevlin Interesting facts about fungi There
Fungi C. Shevlin Interesting facts about fungi There are more than 60 species of fungi that exhibit the phenomenon of emitting light from their bodies known as bioluminescence. C. Shevlin
People eat mushrooms of all shapes, sizes and colors. Yeasts are used in making bread, wine, beer and solvents. Drugs made from fungi cure diseases and stop the rejection of transplanted hearts and other organs. Fungi are also grown in large vats to produce flavourings for cooking, vitamins and enzymes for removing stains.
C. Shevlin Learning Objectives
C. Shevlin Define the terms: saprophytic & parasitic State the structure & life cycle of Rhizopus Explain nutrition in fungi. Outline the structure & reproduction of Yeast Name 2 Beneficial & 2 Harmful fungi Mention that there are Edible and Poisonous fungi
Identify and state functions for the following structures: rhizoid, sporangium, gametangium, zygospore. C. Shevlin Features of Fungi Heterotrophic (Do not make their own food) No chlorophyll
Mostly multi-cellular Made up of threads called hyphae Hyphae combine in masses to form a mycelium Their walls are made of a carbohydrate called chitin (found in insect bodies) C. Shevlin
Features They reproduce by means of spores. They do not ingest food but instead they secrete enzymes onto their food and then absorb the nutrients through their rhizoids. C. Shevlin Nutrition All fungi are heterotrophs i.e. they take in food made
by other organisms. Edible fungi e.g. field mushrooms, truffles Poisonous fungi e.g. death cap Fungi are either: Parasitic Saprophytic C. Shevlin
Nutrition 1. Parasites Live off a live host and cause harm. e.g. athletes foot or ringworm. Obligate parasites can only live off a host and not on their own. e.g. smuts and rusts. 2. Saphrophytes Most fungi are saphrophytes and these live off dead
material. e.g. ear fungus on dead wood. They are essential for recycling nutrients. C. Shevlin Parasitic Fungi Obligate parasites live on live hosts but do not normally kill them Facultative parasites
kill the host and feed on the remains C. Shevlin Some fungi e.g. form symbiotic relationships with other organisms A lichen is an
organism which is a combination of a fungus and an alga C. Shevlin Rhizopus C. Shevlin Bread Mould (Rhizopus)
This fungus grows on the starch in bread, vegetable peelings and stored fruits. Digestion takes place outside of the fungus and the nutrients are absorbed. C. Shevlin Structure Rhizopus
The mould is often called pin mould as it's reproductive structures look like pins. Tubes called hyphae form a big mass called a mycelium. The hyphae digest and absorb the starch in the bread. A stolon is an aerial hyphae (stands up) which allows the mould to spread more quickly.
C. Shevlin C. Shevlin Rhizopus growing on agar Structure of Rhizopus C. Shevlin
Rhizopus to Label C. Shevlin Functions of parts of Rhizopus Part Function Hyphae
Spread the fungus & absorb nutrients Mycelium Spread the fungus Sporangium
Produces the spores Sporangiophore Holds up the sporangium Stolon Allows fungi to spread
Columella Spore release C. Shevlin Structure of Rhizopus C. Shevlin Facts about bread mould:
1. Bread mould consists of threadlike structures called Hyphae 2. Hyphae are tubular with no cross walls and are multinucleate. Each nucleus is haploid. C. Shevlin 3. Large numbers of hyphae are called a mycelium 4. The hyphae digest the substrate on which they
grows 5. Rhizoids provide extra surface area for absorption of the digested material 6. Stolons are arial hyphae which allow Rhizopus to spread sideways C. Shevlin Sporangium Spores Columella
Apophysis Sporangiophore C. Shevlin Rhizopus: Sporangia C. Shevlin Life cycle of Rhizopus Two types of reproduction: 1. Asexual Reproduction
2. Sexual Reproduction C. Shevlin Asexual reproduction in Rhizopus Only involves one parent. Does not involve fertilisation Offspring are identical to parent 1. Hyphae called sporangiospores grow up into the air. Their tips swell to form
sporangium. 2. Cells inside the sporangium produce haploid spores by mitosis. (Sporulation is the process of making spores). 3. In dry conditions the sporangium opens and spores are released. 4. Spores are carried by the wind and if they land on a suitable substrate they germinate. C. Shevlin
C. Shevlin Spores being released from Sporangium C. Shevlin Sexual Reproduction Involves two parents Involves fertilisations and offspring are not
identical to parents. Rhizopus doesn't have a male or female but we call them + or - . Both look identical but sexual reproduction needs a plus and a minus strain to happen. C. Shevlin Steps in Sexual Reproduction 1.Hyphae from opposite strains grow close together.
2. Swellings form opposite each other. 3. The swellings touch. 4. Nuclei (gametes) move into each swelling. 5. Cross walls form and form gametangia. 6. The walls dissolve. 7. Many fertilisations happen to make diploid zygote nuclei. C. Shevlin Sexual Reproduction
8. A tough walled black zygospore forms around the nuclei. 9. Zygospore germinates by meiosis when conditions are right. 10. A haploid hyphae grows out and makes a sporangiophore with a sporangium This produce new haploid spores which can grow. C. Shevlin
C. Shevlin Sexual reproduction Sexual reproduction in Rhizopus can only occur between a plus and a minus strain. C. Shevlin
+ Strain - Strain Sexual reproduction When hyphae from opposite strains grow close together swellings grow on both strains and touch
each other. C. Shevlin + Strain - Strain Sexual reproduction Nuclei from both
hyphae move into these swellings which are now called progametangia. C. Shevlin + Strain - Strain
Sexual reproduction Cross-walls form to produce gametangia. C. Shevlin + Strain - Strain
Sexual reproduction The walls of the gametangia dissolve and a number of fertilisations take place producing diploid zygote nuclei. C. Shevlin
+ Strain - Strain Sexual reproduction + Strain A zygospore forms around these nuclei.
When conditions are suitable the zygospore germinates by meiosis. C. Shevlin - Strain Sexual reproduction
+ Strain A zygospore forms around these nuclei. When conditions are suitable the zygospore germinates by meiosis. C. Shevlin
- Strain Sexual reproduction A hypha grows out of the zygospore and produces a sporangium at the tip. The sporangium opens releasing many
haploid spores which grow into new individuals. C. Shevlin C. Shevlin Review of sexual reproduction Sexual reproduction in Rhizopus can only occur between a plus and a minus strain
When hyphae from opposite strains grow close together swellings grow on both strains and touch each other Nuclei from both hyphae move into these swellings which are now called progametangia Cross-walls form to produce gametangia C. Shevlin Review of sexual reproduction
The walls of the gametangia dissolve and a number of fertilisations take place producing diploid zygote nuclei A zygospore forms around these nuclei When conditions are suitable the zygospore germinates by meiosis A hypha grows out of the zygospore and produces a sporangium at the tip The sporangium opens releasing many haploid spores which grow into new individuals
C. Shevlin Yeast The yeast fungus consists of single cells rather than hyphae C. Shevlin Structure of yeast
C. Shevlin Yeast
Another name for yeast is Saccharomyces. They can be round or oval in shape. They can usually only be seen with an electron microscope. Yeast have thin walls made of chitin. They have a thick cytoplasm with many food storage vacuoles. C. Shevlin
Respiration in Yeast Respiration Yeasts respire anaerobically (without Oxygen) and break down glucose to produce ethanol (alcohol) and Carbon Dioxide. Glucose 2 Ethanol + 2 Carbon dioxide. This process is called fermentation. Fermentation is a type of anaerobic respiration C. Shevlin
Reproduction in Yeast C. Shevlin Reproduction in Yeast Asexual Reproduction This is done by budding. The parent cell divides by Mitosis and the new nucleus and cytoplasm enter the new
cell. If the buds don't separate they form a colony C. Shevlin Asexual reproduction in yeast Asexual reproduction in yeast occurs by budding. The nucleus of the parent cell divides by
mitosis. One of the daughter nuclei enters a small developing bud on the outside of the yeast cell. C. Shevlin Asexual reproduction in yeast This bud can
separate from the parent to become a new individual C. Shevlin Asexual reproduction in yeast This bud can separate from the parent to become a
new individual In some cases the bud does not separate, but can itself bud. In this way long colonies of yeast cells can develop C. Shevlin Budding
C. Shevlin Budding C. Shevlin C. Shevlin Economic importance of fungi
Beneficial fungi Making bread and alcohol e.g. wine and beer. Fungi can be used as a source of food e.g. mushroom C. Shevlin
Economic importance of fungi Harmful fungi Fungi can attack crops e.g. corn and wheat and cause major financial losses as a result Fungi such as athletes foot and ringworm can infect animals Fungi can spoil food e.g.
rhizopus grows on bread C. Shevlin Decomposition Certain species of fungi and bacteria are decomposers. Over time, without decomposition, so much nitrogen would be locked up in leaves and other tissues that there would not be enough nitrogen available for the plant to make new leaves, stems and wood.
The surface of the ground would also be buried by dead leaves and wood lying forever where they fell. C. Shevlin Experiment to grow leaf yeast Sterile means that all microorganisms are destroyed. i.e. there is nothing living. For this experiment we Ash or Ivy leaves. We cut them into circles and stick them face up to the inside of the dish lid. The yeast spores drop off the leaves onto the agar. They
start to grow and form pink colonies. Important to keep the bench sterile we wash our hands, the desk and all equipment with disinfectant. We also put the tweezers etc. through a bunsen flame. This is Saccharomyces roseus. C. Shevlin What have you learned?
C. Shevlin Contemporary issues and Technology Mention of edible and poisonous fungi. Economic importance of fungi: examples of any two beneficial and any two harmful fungi. Practical Activities
C. Shevlin Investigate the growth of leaf yeasts using agar plates and controls C. Shevlin
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