KINGDOM : FUNGI

ABBOTTS COLLEGE

KINGDOM FUNGI

ABBOTTS

TOPICS

•Structure•Characteristics•Diseases

•Neither plants nor animals•E.g. mushrooms, moulds and yeast•Estimated about 1 million species

GENERAL CHARACTERISTICS

Fungi are found everywhere – invisible to the naked eye

Mostly free-living (live in soil, air and dead organic matter)

Are heterotrophs - lack chlorophyll

Saprotrophic – feed on dead organisms Parasitic – get nourishment from a living host and

cause diseases as a result

FORM SYMBIOTIC RELATIONSHIPS

•Some fungi live in symbiotic relationships with plants and animals

•The term symbiosis commonly describes close and often long-term interactions between different biological species.

LICHEN

• An association of a fungi and algae

• The fungus supplies the alga with water and minerals

• The alga makes glucose that is absorbed by the fungus

Lichen thallus (cross-section) X 200.

The algal cells are a lighter colour. They are surrounded by and held in place by fungal hyphae.

MYCORRHIZAE

• Hyphae of a fungus which associate with the roots of many types of plants

• Fungus gets food from the plant

• Plant gets an increased surface area for water absorption

MOST FUNGI ARE USEFUL

• They are primary decomposers of dead organic matter

• Clean the environment

• Nutrients are re-cycled and returned to the soil

FUNGI: REPRODUCTION

•Asexually by means of spores

•Sexually when conditions are unfavourable by means of zygospores

•By budding or binary fission (yeast)

ASEXUAL REPRODUCTION BY SPORES

Spores are the units of asexual reproduction, because a single spore develops into a new organism. By contrast, gametes are the units of sexual reproduction, as two gametes need to fuse to create a new organism.

Sexual reproduction by zygospores

A large multinucleate spore formed by union of similar gametes, as in algae or fungi.

budding BINARY FISSION IN YEAST

STRUCTURE OF FUNGI

•Most are multicellular eukaryotes•Some are unicellular examples (yeast)•Cells walls contain chitin and glucan•Multicellular fungi consist of fine branched threads called hyphae

HYPHAE

HYPHA• Is a multi branched tubular cell filled with cytoplasm• The tube can be continuous (aseptate) or septate

(divided into compartments)

MYCELIUM • Hyphae branch repeatedly to form a network called the mycelium

• Which makes up the thallus (vegetative part of the fungus)

SPORANGIA

•When a fungus reproduces asexually it forms sporangia (spore producing bodies)

HARMFUL FUNGI

•Pathogenic fungi are parasites causing ill health in plants and animals

•Get their nourishment from a living host•E.g. thrush and athletes foot in man•E.g. rust in plants

FUNGAL DISEASES

• Thrush• Rusts• Ringworm• Athlete’s foot

CANDIDIASIS/THRUSH• Also called a candida infection or yeast

infection• Caused by Candida albicans (a yeast

/fungus)• Affects the mucous membranes• Can occur harmlessly in the body• Healthy immune system: friendly bacteria

keep them in check in the intestine• Under certain conditions they grow too fast

and cause an infection• Common in the mouth, vagina or GI tract in

babies

FACTORS WHICH ENCOURAGE GROWTH•Taking antibiotics [reduces the number of

friendly bacteria]•AIDS and cancer weakens the immune system•Stress, poor diet, lack of sleep•Tight clothing promotes moisture build up in

genital areas

MANAGEMENT OF THRUSH

• Oral thrush – antifungal mouthwash

• Vaginal yeast infections – antifungal medication e.g. creams

ATHLETES FOOT

• Caused by a fungus called Tinea

• Grows in damp places• Quite common• Skin flakes and cracks

between the toes• Fungus feeds on keratin

[protein found in skin cells]• Treated with antifungal

powder

PAGE 23

THE END