FUNGI

FUNGI

Ultra structure and characteristics of fungi:

• It is a unicellular or multicellular eukaryotic cell.
• Example of unicellular fungal cell is yeast.
• Example of multicellular fungus is mould, rhizopus and aspergillus.
• They are fresh water and land living organisms.
• Fungi do not consist of any chloroplasts.
• It cannot synthesize its own food.
• It feeds by absorption or adsorption mode of nutrient.
• Study of fungus is known as mycology.

Distribution:

• It is a primary terrestrial organism.
• 3/4^th of this fungus interacts with plant roots. It is known as mycorrhizal interaction.
• Sometimes fungus may be interacted with algae. It is known as lichens.

Importance of fungus:

• Generally 90,000 species of fungus is distributed.
• They contain both beneficial and harmful effects.
• Beneficial effects:

In industries:

It is used in industries for preparation of fermented food.

Example: wine, beer, antibiotics etc.

Decomposition:

It easily degrades the complex compounds present in the soil.

Harmful effects:

• Highly pathogenic and causes infection to human, animals and plants.
• Food spoilage. Example: bread.

Structure of fungus:

• Body of fungus is known as thallus.
• Shape and size of thallus varies from species to species.
• Outer most layer is made up of chitin.
• Chitin substance consists of flexible nitrogen containing polysaccharides and n-acetyl glucosamine residues.
• Flagella are absent.

Yeast:

• It is a unicellular, eukaryotic organism.
• It consists of distinct nucleus.
• Its size is slightly greater than the bacterial cell.

Mold:

• It is a multicellular, eukaryotic organism.
• It has a long, filamentous and branched like structure.
• Generally hyphae are present in mycelium.
• Generally they are in aggregated (sticky) form.
• Hyphae sometimes consist of mycelial bodies.
• Hyphae moves and grows towards the cytoplasm. It is known as coenocytic fungus. Example: in mychorrhiza, root cells are penetrated by fungus.
• Some barriers in cell wall known as septae are present.
• During infection two kinds of fungi are formed.

1. yeast form (y- form)

2. mold form (m- form)

• y -form produces spores.
• M -form process hyphae.

Nutrient and metabolism of fungi:

Ø Fungi do not have chloroplasts.

• They exhibit saprophytic mode of nutrition.
• They feed on dead plants and animals.
• It converts complex substances to simple organic and inorganic compounds.
• It is a kind of biodegradation.
• It is eco-friendly.

Reproduction:

Ø It reproduces by two types:

i. Asexual reproduction

ii. Sexual reproduction

Asexual reproduction:

CELL DIVISION:

Parent cell divides into two daughter cells.

BUDDING:

Parent cell gives out some buds and bud separates out and develops into separate organism.

ASEXUAL SPORES:

It produces five types of spores.

1. Arthroconidal spores

2. Chlamydospores

3. Sporangiospores

4. Conidiospores

5. Blastospores

Arthroconidal spores:

Mature hypha separates from parent hyphae and develops into a complete organism.

Chlamydospores:

Mature hypha separates from parent cell along with cell wall.

Sporangiospores:

Spores forms sacs within the hyphae, and come out along with the sac.

Conidiospores:

Spores are released from hyphae by rupturing the cell wall of hyphae.

Blastospores:

Mature mother cell produces spores.

Sexual reproduction:

During sexual reproduction, hyphae form special parts known as gametogonia. Gametes are developed from gametogonia. Male and female gametes combined to form zygote.