Fungi

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Transcript of Fungi

These are heterotrophic eukaryotic organisms. They use decaying organic material as food and are therefore called saprophytes. Many of them have the capacity to become multicellular organisms at certain stages in their lives. They have cell-walls made of a tough complex sugar called chitin.

Examples are Yeast and Mushrooms.

Filaments of fungi are called hyphae.

The cell walls contain chitin.

The MYCELIUM is a mat of hyphae visible to the unaided eye (bread mold)

Some hyphae may divided by cross sections called septa

Fungi reproduce in both ways, 1) Sexually and,

2) AsexuallyAsexual Reproduction- production of various types of sporesSporangiophores- 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.

• They are called Saprophytes, they act as recyclers of dead organic matter, obtaining food from this material.

• Hyphal tips release enzymes that eventually decompose and release organic materials into the surrounding environment.

• Saprophytic fungi appear on dead trees, logs, plant litter such as leaves, and even dead insects and animals. Examples: "Gem-studded Puffball" (Lycoperdon perlatum) and "Turkey Tail"(Trametes versicolor).

• Fungi are important decomposers of dead animal and plant matter. They break down dead organic matter into simple compounds that can be absorbed by the plants around it. During the process of decomposing matter, fungi returns carbon dioxide to the atmosphere. Green plants use the carbon dioxide during photosynthesis to produce food. 

• Beneficial Effects of Fungi* Decomposition - nutrient and carbon recycling.* Biosynthetic factories. Can be used to produce drugs, antibiotics, alcohol, acids, food (e.g., fermented products, mushrooms).* Model organisms for biochemical and genetic studies.• Harmful Effects of Fungi* Destruction of food, lumber, paper, and cloth.* Animal and human diseases, including allergies.* Toxins produced by poisonous mushrooms and within food (e.g., grain, cheese, etc.).* Plant diseases.

Fungal diseases are called mycoses and those affecting humans can be divided into four groups based on the level of penetration into the body tissues:

Superficial mycoses are caused by fungi that grow on the surface of the skin or hair.

Cutaneous mycoses or dermatomycoses include such infections as athlete's foot and ringworm, where growth occurs only in the superficial layers of skin, nails, or hair.

Subcutaneous mycoses penetrate below the skin to involve the subcutaneous, connective, and bone tissue.

Systemic or deep mycoses are able to infect internal organs and become widely disseminated throughout the body. 

V.VAMSI KRISHNAClass : IX Roll No : 919