FUNGI:

FUNGI:

Eukaryotic organisms of the kingdom Fungi, which lack chlorophyll and vascular tissue and range in form from a single cell to a body, mass of branched filamentous hyphae that often produce specialized fruiting bodies. The kingdom includes the yeasts, molds, smuts, and mushrooms.

OR

Any member of a kingdom of organisms (Fungi) that lack chlorophyll, leaves, true stems, and roots, reproduce by spores, and live as saprotrophs or parasites.

CHARACTERISTICS OF FUNGI:

1. All are eukaryotic: Possess membrane-bound nuclei (containing chromosomes) and a range of membrane-bound cytoplasmic organelles (e.g. mitochondria, vacuoles, endoplasmic reticulum).

2. Most are filamentous: Composed of individual microscopic filaments called hyphae, which exhibit apical growth and which branch to form a network of hyphae called a mycelium.

3. Some are unicellular: e.g. yeasts.

4. Protoplasm of a hypha or cell is surrounded by a rigid wall: Composed primarily of chitin and glucans, although the walls of some species contain cellulose.

5. Many reproduce both sexually and asexually: Both sexual and asexual reproduction often result in the production of spores.

6. All are achlorophyllous: They lack chlorophyll pigments and are incapable of photosynthesis.

7. Possess characteristic range of storage compounds: e.g. trehalose, glycogen, sugar alcohols and lipids.

8. May be free-living or may form intimate relationships with other organisms: i.e. may be free-living, parasitic or mutualistic (symbiotic).

9. Fungi are Heterotrophs: Obtaining energy from absorption.

10. Saprophytes: Obtain their energy from dead organic material.

11. Parasites: Obtain their energy from living host.

12. Grow in wide range of habitats: including extreme environment such as deserts or area with high salt concentration as well as in deep sea sedimentation.

13. Hydrogen ion concentration: Grow in an acidic medium of about 5.0 ph.

14. Temperature: 25 °C (room temperature) and 37 °C (body temperature).

 15. Environment: Grows in both aerobic and anaerobic environments.

REPRODUCTION:

Most fungi reproduce both sexually and asexually.

►  Asexual reproduction – production of various types of spores

§  Sporangiophores- upright stalk with an enclosed sac ( bread mold)

§  Conidia - upright stalk with no enclosed sac (penicillin)

§  Fragmentation – hyphae dry out and shatter releasing individual cells that act like spores (athlete’s foot)

§  Budding – small offspring

►  Sexual reproduction

§  “plus and minus” mating types

§  Hyphae of different mating types fuse and give rise to a specialized structure that produces spores ( diploid)

§  Most fungi are haploid throughout most of their life cycle

►  When environmental conditions are favorable, asexual reproduction occurs rapidly.  When unfavorable conditions stress the organism, sexual reproduction occurs and the offspring have an increased like hood that they will be better suited for the environment.

GENERAL CLASSIFICATION OF FUNGI

1.     GYMNOMYCOTA: which ingest particular nutrients and lack cell wall in vegetative stage

                 • Also called “MYXOMYCETES

                 • Mobile or immobile. 

2.     MASTIGOMYCOTA : producing flagellated cells.

                  • Sexual reproduction by flagellated spores (+/), Organisation without cellular separation  (cenocytic).

•         Important cause of diseases:

§   Plant (Mildew, Ink). 

§  Animal (Trout disease: saprolegniosis).

3.     AMASTIGOMYCOTA : fungi in which flagella is absent.

§  Zygomycetes.

§  Ascomycetes.

USES OF FUNGUS:

1.     Yeast for fermentation.  Yeast breaks down sugars to produce ethyl alcohol and CO₂

2.     Brewing of alcoholic beverages: beer, wine – yeast turns sugars of grains, grapes into alcohol and carbon dioxide (bubbles)

3.     Bread making – carbon dioxide bubbles help dough rise

4.     Cheese production.

5.     Edible fungi are the sexual structures of fungi, the mycelium remains Mushrooms, Morels & Truffles.

6.     Corn smut – a parasite of corn, is actually eaten in Mexico, a delicacy (huitlacoche)

7.     Poisonous – some very dangerous intoxicants

8.     Hallucinogenic fungi.

9.     Fungi was used by Alexander Fleming to discover penicillin, and there are many other medicines that have since been synthesized from fungi.

10.                       Fungi produce a range of compounds that alter the colour of food. For instance, Monoascus purpureus has been traditionally used for the production of red wine.

11.                       While many flavours are produced by bacteria, fungi are responsible for a range of flavours including terpenes, menthol and lactones. Fungi also produce compounds that deodorise offensive and neutralise bitter flavours.