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19.1 Diversity of Protists KEY CONCEPT Kingdom Protista is the most diverse of all the kingdoms. 19.1 Diversity of Protists Protists can be animal-like, plantlike, or funguslike. • Protists are eukaryotes that are not animals, plants, or fungi. 19.1 Diversity of Protists • Animal-like protists consume other organisms. – heterotrophs – single-celled 19.1 Diversity of Protists • Plantlike protists are photosynthetic. – single-celled, colonial, or multicellular – no roots, stems, or leaves 19.1 Diversity of Protists • Funguslike protists decompose dead organisms. – heterotrophs – can move, whereas fungi cannot 19.1 Diversity of Protists Protists are difficult to classify. • Protista is one kingdom in the domain Eukarya. 19.1 Diversity of Protists • Protist classification will likely change. – Some protists are not closely related. – Molecular evidence supports reclassification. 19.2 Animal-like Protists KEY CONCEPT Animal-like protists are single-celled heterotrophs that can move. 19.2 Animal-like Protists Animal-like protists move in various ways. • Animal-like protists are often called protozoa. macronucleus contractile vacuole food vacuole oral groove micronucleus cilia 19.2 Animal-like Protists • Protozoa with flagella are zooflagellates. – flagella help zooflagellates swim – more than 2000 zooflagellates 19.2 Animal-like Protists • Some protists move with pseudopods. – change shape as they move – amoebas 19.2 Animal-like Protists • Some protists move with pseudopods. –change shape as they move – amoebas – foraminifera 19.2 Animal-like Protists • Some protozoa move with cilia. – cilia help protists swim and capture food – more than 8000 ciliates macronucleus contractile vacuole food vacuole oral groove micronucleus cilia 19.2 Animal-like Protists Some animal-like protists cause disease. • Protists cause some wellhuman liver known infectious diseases. • Malaria is caused by Plasmodium and spread by mosquitoes. • Sleeping sickness is caused by Trypanosoma and spread by flies. • A giardia infection is caused by Giardia and spread through water. sporozoites liver cells developed parasites red blood cells Malaria Infection 19.3 Plantlike Protists KEY CONCEPT Algae are plantlike protists. 19.3 Plantlike Protists Plantlike protists can be single-celled or multicellular. • Photosynthetic plantlike protists are called algae. colony daughter colony 19.3 Plantlike Protists • Euglenoids are a large group of plantlike protists. – mostly photosynthetic – some heterotrophic – single-celled pellicle contractile – one or two flagella vacuole nucleus flagellum chloroplast eye spot 19.3 Plantlike Protists • Dinoflagellates are mostly marine plantlike protists. – have two flagella – may be bioluminescent – have stiff protective plates – can cause red tide Dinoflagellates 19.3 Plantlike Protists • Diatoms are plantlike protists with glasslike shells. – shells made of silica – produce large amounts of oxygen 19.3 Plantlike Protists • Multicellular algae are classified by their pigments. – Green algae contain chlorophyll a and b. – Brown algae contain chlorophyll c. – Red algae contain chlorophyll a and phycoerythrin. 19.3 Plantlike Protists Many plantlike protists can reproduce both sexually and asexually. • All algae can reproduce asexually. – Multicellular algae can fragment. – Chlamydomonas divides into zoospores. 19.3 Plantlike Protists • Some algae produce sexually. – Some species alternate generations. – Sexual reproduction can be triggered by environmental stress. 19.4 Funguslike Protists KEY CONCEPT Funguslike protists decompose organic matter. 19.4 Funguslike Protists Slime molds and water molds are funguslike protists. • Slime molds have both funguslike and animallike traits. – decomposers, like fungi – can move, like animals 19.4 Funguslike Protists • Slime molds can be plasmodial or cellular. – Plasmodial slime molds are giant cells with many nuclei. – Cellular slime molds contain independent cells. 19.4 Funguslike Protists • Water molds are freshwater, funguslike protists. – one type of water mold caused Great Potato Famine of Ireland in the 1800’s – made of branching strands of cells – can be parasites of plants or fish 19.5 Diversity of Fungi KEY CONCEPT Fungi are heterotrophs that absorb their food. 19.5 Diversity of Fungi Fungi are adapted to absorb their food from the environment. • Plants and fungi have different traits. – Fungal cell walls are made of chitin. – Plant cell walls are made of cellulose. – Plants have chlorophyll and photosynthesize. – Fungi absorb food through hyphae. 19.5 Diversity of Fungi • Fungi are multicellular organisms, with the exception of yeasts. – hyphae – mycellium – fruiting body 19.5 Diversity of Fungi Fungi come in many shapes and sizes. • Primitive fungi are aquatic and have flagellated spores. • Sac fungi form a reproductive sac, or ascus. – Yeasts are single-celled sac fungi. – Morels and truffles are multicellular sac fungi. 19.5 Diversity of Fungi • Bread molds are often found on spoiled food. – form zygospores during reproduction – mycorrhizae belong to this group 19.5 Diversity of Fungi • Club fungi have fruiting bodies which are club-shaped. – reproductive structures called basidia – include mushrooms, puffballs, and shelf fungi 19.5 Diversity of Fungi Fungi reproduce sexually and asexually. • Most fungi reproduce both sexually and asexually. – Yeasts reproduce asexually through budding. – Yeasts form asci during sexual reproduction. 19.5 Diversity of Fungi • Multicellular fungi have complex reproductive cycles. – distinctive reproductive structures 19.5 Diversity of Fungi • Multicellular fungi have complex reproductive cycles. – life cycles may include either sexual or asexual reproduction or both 19.5 Diversity of Fungi • Multicellular fungi have complex reproductive cycles. – life cycles may include either sexual or asexual reproduction or both 19.5 Diversity of Fungi • All fungi form spores and zygotes. 19.6 Ecology of Fungi KEY CONCEPT Fungi recycle nutrients in the environment. 19.6 Ecology of Fungi Fungi may be decomposers, pathogens, or mutualists. • Fungi and bacteria are the main decomposers in any ecosystem. – decompose dead leaves, twigs, logs, and animals – return nutrients to the soil – can damage fruit trees and wooden structures 19.6 Ecology of Fungi • Fungi can act as pathogens. – human diseases include ringworm and athlete’s foot – plant diseases include Dutch elm disease 19.6 Ecology of Fungi • Fungi can act as mutualists. – lichens form between fungi and algae – mycorrhizae form between fungi and plants 19.6 Ecology of Fungi • Fungi can act as mutualists. – relationships form between fungi and some insects 19.6 Ecology of Fungi Fungi are studied for many purposes. • Fungi are useful in several ways. – as food – as antibiotics – as model systems for molecular biology