ch. 21 protists by: brianna shields april 27, 2006

CH. 21 Protists

By: Brianna ShieldsApril 27, 2006

DO NOW

What

GOAL List the characteristics of protists List three environments where protists can be found Identify the unifying features of protists Distinguish asexual and sexual reproduction of

Chlamydomonas Differentiate two ways multicellular protists reproduce

sexually Identify how amoebas and forams move Describe the structure of diatoms Contrast three kinds of algae Differentiate three different kinds of flagellates Summarize the general characteristics of a Paramecium Identify two ways that protists affect human health Name three human diseases other than malaria, caused by

protists Summarize how malaria is transmitted Evaluate the methods used to control malaria

PROTISTS

Protists Diverse Animal, plant and fungus-like Flagella, cilia for locomotion Water environments Some parasitic Can respond to environment Eyespots (light sensitive) Sexual & Asexual Unicellular & multicellular

PROTISTS

First Eukaryotes

Evolved through endosymbiosis

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PROTISTS

Protist Kingdom

Protozoa= heterotrophic protists Algae= photosynthetic protists

PROTISTS Protist

Reproduction Sexual Reproduction in Unicellular

Protists Occurs during environmental stress Cell divides into two gametes Gametes from different individuals fuse to

form a zygospore (zygote) with thick protective wall

Zygospore withstands environmental conditions until they become favorable again

Zygospore produces cells that break out of its wall and grow into mature cells

PROTISTS Protist

Reproduction Sexual Reproduction in Multicellular

Protists Alternation of generations

Adult sporophyte alga produces sporesSpores grow into gametophytesGametophytes produce gametes that

fuseFused gametes divide through mitosis to

form new sporophyte Conjugation

Two cells align side by side and pass genetic material between their cell walls

Assessment

Describe two ways sexual reproduction can occur in multicellular protists

Summarize why protists are not classified with the other three eukaryotic kingdoms

List three characteristics of protists

PROTISTS• Amoebas • Unicellular, heterotroph

• Pseudopodia- Flexible, cytoplasmic extensions for moving and eating

• No cell wall or flagella• Freshwater, saltwater and soil• Reproduce through fission• Some parasitic

– Ex: Entamoeba histolytica causes Amebic dysentery when transmitted in contaminated food or water

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PROTISTS• Foraminifera • Live in sand or attach to rocks

• Covered by calcium carbonate tests (shells) in a spiral shape

• Thin streams of cytoplasm extend out of tests for swimming and catching prey

• Algae live under the tests (symbiosis)• Dead foram tests accumulate on ocean floor

creating limestone deposits

PROTISTS

Algae Autotrophic Unicellular and Multicellular

PROTISTS• Green

Algae• Mostly freshwater, some marine• Mostly unicellular, some

multicellular• Sexual and asexual stages• Part of marine plankton, inhabit

damp soil, live with cells of other organisms

PROTISTS• Red

Algae• Multicellular• Warm ocean waters• Absorbing light that penetrates

deep waters• Used to make agar and

carrageenan• Complex life cycle (sometimes

with alternation of generations)

PROTISTS• Brown

Algae• Multicellular• Marine environments• Kelp grows on coasts- feeds and

shelters other organisms• Largest organisms on Earth• Reproduced by alternation of

generations

PROTISTS• Diatoms • Unicellular

• Producers in oceans and lakes• Double silica shells like boxes with lids• Diatomaceous Earth

– Empty shells are mined commerciall– Used as an abrasive– Sparkle in road paint– Natural pest control (sharp edges puncture

pests)• Glide by secreting chemical through holes in

their shells• Asexual reproduction- two halves of shell

separate, matching half regrows• Each generation is smaller and smaller-

eventually slips out of its shell to regrow to normal size

PROTISTS• Flagellat

es• Dinoflagellates

– Mostly marine– Unicellular Autotroph– Two flagella– Protective cellulose coat encrusted

with silica– Spin through water like a top– Asexual– Some produce powerful toxins (ex:

red tide)


es• Euglenoids

– Freshwater– Two flagella– Most photosynthetic, some

heterotrophic– Pellicle inside cell membrane allows

it to change shape– Eyespot- detects light– Mitotic reproduction

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PROTISTS

Flagellates

Kinetoplasts Unicellular, heterotrophs One – one thousand flagella Asexual & Sexual Closely related to Euglenoids Trichonympha live symbiotically in

termite gut Trypanosomes cause African

Sleeping Sickness in humans


es• Ciliates (ex: Paramecium)

– Many cilia (hairs)– Unicellular, heterotrophs– Tough, flexible wall allows

movement– Contractile Vacuole regulates water

concentration– Asexual: Fission– After 700 generations must

reproduce sexually through conjugation or they will die

PROTISTS• Protista

n Molds• Cellular Slime Molds

– Ameba-like– Lives independently moving through

soil, ingesting bacteria– Clump with others in a multicellular

colony called a slug during environmental stress

PROTISTS• Protistan

Molds• Plasmodial Slime Molds

– Group of organisms that stream along as Plasmodium (mass of cytoplasm resembling oozing slime)

– During stress, divides into small mounds

PROTISTS• Protista

n Molds• Other Molds

– Water molds– White rusts– Downy mildews– Grow on dead algae and animals in

fresh water– Many are plant pathogens

• Phytophthora infestans cauases Irish potato famine of 1845-1847 (400,000 people starved to death)

PROTISTS• Sporozoan

s• Form spores• Parasitic- serious diseases• Infect animals- transmitted from host to host• Nonmotile• Sexual and asexual• Large female gamete and small male gamete

form a zygote that withstands unfavorable condtions

• Transmitted by – Blood-feeding insects– Food, water contaminated with infected animal

feces– Ex: Malaria

Assessment

Fill in a graphic organizer comparing the characteristics of various members of the protist kingdom

Describe a pseudopodium Identify the role of diatoms in the

aquatic food chain Explain how protistan molds differ

from fungi Euglena is a protozoan not an alga. Is

this an accurate statement? Why or why not?

PROTISTS

Protists and Humans

Cause disease in humans and livestock- costly to prevent and treat them

Beneficial Protists Live in digestive tracts

Cow need them for digesting celluloseSupport food chains Produce oxygenDetritivores- recycle nutrients

PROTISTS• Malaria • One of most deadly human diseases

– 100 million people have it at any given time

– 3 million die each year – Symptoms: chills, fever, sweating,

confusion, thirst– Death results from: anemia, kidney failure,

brain damage

• Caused by Plasmodium spread by mosquito bites

PROTISTS

Malaria Life Cycle Mosquito bites and injects thousands of

PlasmodiumSporozoites infect liver, rapidly dividing

Merozoite cells infect rbc’s and divide rapidly

Every 48 hours rbc’s rupture spilling out more merozoites and toxins (causing fever & chills)

Some merozoites in blood develop into gametes

Mosquito bites infected human- gametes join in mosquito to form zygote

Zygote divides to form sporozoites that migrate to mosquito’s salivary glands



PROTISTS

•Malaria

• Treatment and Prevention– Treated with quinine from bark

of cinchona tree in South America

– Reduce mosquito population by • spraying insecticides• reducing breeding grounds• introducing predators to eat

mosquito larva

Assessment

Describe two ways protists affect human health

Describe three human diseases caused by protists

Diagram the Malaria life cycle and describe how it is transmitted

ch. 21 protists by: brianna shields april 27, 2006

Documents

unicellular protists

malaria slide

photosynthetic protists

protists foraminifera

water slide

endosymbiosis slide

ways multicellular protists

heterotrophic protists