Chapter 8: Protists and Fungi

Aim: What characteristics do all protists share?

Protists Is a one or many celled organism that lives in moist or wet surroundings Have eukaryotic cells Usually reproduce asexually by cell division Some reproduce asexually by regeneration Some can reproduce sexually

Are classified into three groups: 1. Plantlike 2. Animal-like 3. Fungus-like Few fossils of these organisms exist because most protists do not have hard parts By studying DNA and the structure of modern protists, they are gathering information on how they are related to one another and to other organisms

Most protists have an ancestor that was one-celled, had a nucleus and other cellular structures Those who are able to make their own food may have a different ancestor

Aim: What is the difference between plantlike protists and animal-like protists?

Plant-like Protists Contain the pigment chlorophyll Can make their own food Many have cell walls like plants Have structures like roots to hold them in place Plantlike protists known as algae 6 types of algae

1. Diatoms Found in freshwater and saltwater Golden-brown pigment that covers up the chlorophyll Secrete glasslike boxes around themselves (made of silica) 2. Dinoflagellates-mean “spinning flagellates” Have two flagella Most live in saltwater Some are parasites

3. Euglenoids Have characteristics like both plants and animals One-celled Many have chloroplasts Can produce own food When light is not present they feed on bacteria and other protists Has a strong, flexible layer that helps it move and change shape Have flagellum Eyespot-helps them find light

4. Red Algae Many-celled Called seaweed Contain chlorophyll, but produce large amounts of a red pigment Found in deepest water (175 to 200 m) 5. Green algae More than 7,000 species Contain large amounts of chlorophyll One-celled or many-celled Live closer to the surface of water Can live in moist areas too (damp tree trunks)

6. Brown Algae Contain a brown pigment along with chlorophyll Live in cool, saltwater Many-celled Live at a depth of 35m Ex: kelp

Importance of Algae Known as the “grasses of the sea” One-celled algae (diatoms and dinoflagellates) are most important food source Euglena important food source for organisms that live in freshwater Produce oxygen Used in foods Carrageenan used in cosmetic and food industries (salad dressings, toothpastes)

Algin used to thicken food such as ice cream and marshmallows Ancient deposits of diatoms used in insulation, filters and road paint

Animal-like Protists One-celled animal-like protists are known as protozoans Classified by how they move Live in or on other living or dead organisms that are found in water or soil Have specialized vacuoles for digesting food 4 ways of moving

1. Ciliates Have cilia Cilia helps the organism move Have 2 nucleui Macronucleus-controls feeding, exchange of O 2 and CO 2 Micronucleus-deals with reproduction Feed off of bacteria Ex: Paramecium

2. Flagellates Move by flagella Many of these species live in freshwater Some are parasites Ex: Proterospongia 3. Pseudopods Some move and feed through an extension of their cytoplasm Pseudopod means “false foot” Found in freshwater and saltwater Certain types are parasites in animals

Ex: amoeba 4. Other Protozoans Are unable to move on their own All are parasites of humans and other animals Life cycles involve asexual and sexual reproduction Ex: parasite that causes malaria

Aim: Why are protozoans important?

Importance of Protozoans Important source of food for some organisms Some shelled protozoans become sediments, which help indicate where petroleum may be found Live in the digestive tract of termites and produce wood-digesting enzymes for the termites Cause diseases in humans-are parasites

Aim: What are the characteristics of fungus-like protists?

Fungus-like Protists Produce spores like fungi Can move from place to place using pseudopods Take in food from an outside source 1. Slime molds: Form delicate, web-like structures on the surface of their food supply These structures are brightly colored Move by means of pseudopods Found in decaying logs or dead leaves

Found in moist, cool, shady environments Reproduce by spore reproduction 2. Water Molds and Downy Mildews Live in water or moist places Grow as a mass of threads over a plant or animal Digestion takes place outside of these protists Cell walls resemble those of a plant’s Some water molds are parasites

Water molds appear as fuzzy white growths on decaying matter Downy molds are plant parasites ◦ Ideal growing conditions are warm days, and cool, moist nights

Importance of Fungus-like Protists Some help breakdown dead organisms Causes diseases in plants and animals Cause lesions in fish farms Downy mildews caused the Irish potato famine Downy mildews still cause destruction of lettuce, corn and cabbage

Aim: Why are protists so difficult to classify?

Aim: What characteristics do all fungi share?

Fungi Some believe their ancestors was a green or red algae Others hypothesize they share an ancestor with flagellated protists and slime molds Many-celled Body consists of hyphae-produce enzymes that help breakdown food Known as saprophytes Others are parasites

Once were classified as plants because some grow anchored in the soil and have a cell wall Do not contain chlorophyll and can’t undergo photosynthesis Grow best in warm, humid areas Asexual and sexual reproduction involves the production of spores Asexual-cell division produced spores, which grow identically to the original fungus

Identified as neither male or female Sexual reproduction can occur when the hyphae of 2 different fungi grow close together Reproduction structure will grow Spores are produced in this structure, that will grow into new fungi

Aim: How are fungi classified?

Classification of Fungi Classified into 3 main groups based on the type of structure formed by the joining of hyphae 1. Club Fungi: Mushroom is only the reproductive structure of fungus Most of the fungus grows as hyphae or on the surface of its food source Spores are produced in a club-shaped structure called a basidium

2. Sac Fungi Examples: yeasts, molds, morels and truffles Contains more than 30,000 species Spores are produced in a little, saclike structure called an ascus Yeasts are one-celled, reproduce sexually by spores and asexually by budding

3. Zygote Fungi Produce spores in a round spore case called a sporangium Spores grow and develop in warm, moist areas that have a food supply Ex: black fuzzy mold that grows on food

Imperfect Fungi Never reproduce sexually Difficult to classify No evidence that their life cycle has a sexual stage Ex: Penicillium

Aim: What are lichens?

Lichens Is an organism that is made of a fungus and either green algae or cyanobacterium The 2 organisms have a relationship, in which they both benefit from The algae or cyanobacteria grows on the fungus and the fungus gets food from made by them The algae gets a moist, protected place to live

Are an important food source for oxens and caribou Help the weathering of rocks-lichen release acid that helps break down the rock Scientists use them as indicator organisms to monitor pollution levels

Aim: How do fungi interact with plants?

Some fungi interact with plant roots and form a network of hyphae and roots called mycorrhizae Fungus helps the plant absorb more of certain nutrients from the soil better than the roots can Plant supplies food and nutrients to the fungi Some plants can not grow without the mycorrhizae-lady’s slipper orchids

Found a fossil in 1999 that was 460 million years old The fossil indicated that fungus formed a relationship with plant roots This relationship allowed plants to successfully move from water to land

Aim: What is the importance of fungi?

Importance of Fungi Some eaten for food Some cheeses are produced using fungi Yeasts are used in the bakery Many fungi cause diseases in plants and animals Sac fungi causes millions of dollars of damage in crops Ringworm and athlete’s foot are caused by fungi

Other fungi can cause respiratory infections Some produce natural antibiotics Penicillin comes from penicillium Most important as decomposers that break down organic materials