7ch8Protists

Protists - a member of a group of eukaryotic organisms, which have a membrane bound nucleus.

● protists are a diverse group with many different adaptations

● share some characteristics with plants, animals, fungi

Reproduction

Most reproduce asexually - exact copy of the parent

Some reproduce sexually - genetically different from the parent

Classification

A protist is any eukaryote that cannot be classified as a plant, an animal, or a fungus.

Protists are classified as plantlike, animal-like, or funguslike

Plantlike Protists

Diatoms - microscopic plantlike protist with a hard outer wall

● very common,● diatoms look like colored glass - their cell walls contain

silica

Plantlike Protists

Dinoflagellates - protists with a flagella so it can

move around, some glow in the dark

Plantlike Protists

Euglenoids - instead of a cell wall, they have a rubbery cell coat, a flagellum, eyespots that detect light, and chloroplasts to make their own food

prey for tadpoles and small fish

Plantlike Protists

Algae are plantlike protists that produce food through photosynthesis using light energy and carbon dioxide.

Some are large and multicellular, most are small, unicellular

Algae

Classified as Red, Green, or Brown

Red and brown appear similar to plants,

● have holdfasts to attach to rocks instead of roots● do not have a complex system for water transport like

plants

Green Algae

Volvox - many volvox cells come together to form a large sphere and function as a group

Importance of Algae

Ingredient of foods like ice cream, pudding, marshmallows

Important in the ecosystem - provide food and shelter

- remove pollution from water

Problems in ecosystem - can overpopulate and produce wastes that poison other organisms often called a red tide algal bloom

Animal-like Protists

Protozoans - protists that resemble tiny animals

● do not have chloroplasts● microscopic and unicellular● most live in wet environments

Ciliates

Cilia - short, hairlike structures that grow on the surface of some protists

Paramecium - protist with cilia and two types of nuclei

Flagellates

● uses flagella to move● eat decaying matter● many live in the digestive of animals

Sarcodines

Animal-like protists with no specific shape

Amoeba - common, with an adaption for movement

Pseudopod - a temporary “foot” that forms as the

organism pushes part of its body outward.

Sarcodines get nutrients and energy by:

● ingesting other organisms● make their own food● live in the digestive system of humans

Importance of Protozoans

Decompose dead plant and animal matter

Cause disease as parasites

Example: malaria p. 272

Funguslike Protists

Slime and Water Molds

Slime molds - cell material floating in a slimy mass

- absorb nutrients from other organic matter

Water mold - feeds on dead organisms or as a parasite

- often causes diseases in plants

Importance of Funguslike Protists

Decompose dead organic matter

Many attack and consume living plants

Example: Great Irish Potato Famine in 1845

destroyed over half of the potato crop

Lesson 2 Fungi

● World’s largest organism● Eukaryotes● 1.5 million species● heterotrophs - cannot make their own food● decompose organic matter by dissolving it with chemicals ● some are parasites

Hyphae - threadlike structures usually underground that

absorb minerals and water

Mycelium - a network of hyphae

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Types of Fungi

Classified by appearance and type of reproduction structures

Can reproduce sexually and asexually

Almost all reproduce asexually by spores

Spores - small, reproductive cells with a strong outer

covering

Types of Fungi

Club Fungi - named for their various shapes, characteristics

Puffballs p.276

Stinkhorns

Bird’s nest fungus p.278

Mushrooms

Mushrooms - named for their clublike structure above ground

called a basidiocarp.

Basidia - reproductive structures inside the basidiocarp

that produce sexual spores

Sac Fungi

named for their reproductive structures - spores develop on a structure that looks like a sack (ascus)

Ascus - structure where spores develop

common types: yeast, diaper rash,

Zygote Fungi

Have stalks called zygosporangia that release spores

Example: bread mold,

fungi in damp places like a damp basement or a

shower curtain

Imperfect Fungi

No sexual reproductive stage

Examples: athlete’s foot

blue cheese - the blue color comes from fungi

Importance of Fungi

Used in the production of many food products

Cheese, bread, soda, chocolate, meat substitute

Make antibiotics

Importance of Fungi - Decomposers

Fungi break down organic matter for food

● By decomposing dead organic matter, they recycle nutrients in the soil

● Fungi also break down pollution, including pesticides in the soil

Fungi and Plant Roots

Many plants and fungi grow together

The roots of plants and the hyphae of fungi weave together to form a structure called mycorrhiza

MycorrhizaExchange molecules: fungi break down decaying matter in the soil and provide some of these nutrients to the plant

The plant provides some sugar from photosynthesis to the hyphae of the fungus

The hyphae also increase the plant’s ability to absorb water

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Health and Medicine

Fungi can make you sick: athlete’s foot, rashes, allergies, pneumonia, thrush.

Fungi can also be used to make medicine: penicillin

The fungus penicillium restricts bacterial growth

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Lichens

A structure formed when fungi and certain other photosynthetic organisms grow together.

Usually a sac or club fungus that lives together with a green algae or a photosynthetic bacterium.

The fungus’ hyphae grow in a layer around the algae cells

Benefits of Lichens

● Can survive harsh environments - fungus provides water and nutrients, algae can make food from photosynthesis.

● Food for other organisms● Create soil

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