Chapter 7. Protists

☞ Protists(원생동물)

- currently 100,000 species, 35,000 species found in fossils

- lying in classification gap bwtn prokaryote and smallest animal and plants

- all are unicellular, some exist as colonies

- microscopic size ~ mm

- practice all known modes of feeding

-> phagocytosis

-> absorb thru membrane

-> parasites causing human and animal disease

-> photosynthesis

- movement by cilia, flagella, cytoplasmic extension(pseudopodia, 위족)

- physiological variety

-> fungus-like, plant-like, animal-like,

-> combined characters of plants and animal, fungi and animal

- asexual reproduction by mitosis is common, but sexual also

- contain cellular compartment, subcellular organelles

Chapter 7. Protists

Diatom(규조류)Diatom(규조류) Slime mold(점균류)Slime mold(점균류) VolvoxVolvox

Amoeba proteusAmoeba proteus ChlamidomonasChlamidomonas TrypanomonasTrypanomonas

Chapter 7. Protists

1. Protozoa - protozoa = proto(first) + zoa(animal)

- lack cell wall, ingest food particle, move freely, no spore production

- 40,000 species in aquatic environment, in moist soil, or as parasite

- under ideal condition -> active feeding form (trophozoites, 영양체)

- harsh condition -> transform into protective body (cysts, 피낭) => bioterrorism에 이용

- environmental physiology : decomposer and recycle the nutrients

- in aquatic food chain ->important as zooplankton(동물플랑크톤)

- feeding on micro algae, convert into nutrients -> marine invertebrate의 먹이

- on land, nutrient-releasing functions in the digestive tracts of ruminant animal

- classify four groups based upon motion type

-> amoebas : move by pseudopod

-> flagellates : “ by flagella

-> ciliates : “ by cilia

-> sporozoa : nonmotile in the adult form

Four major group of protozoaFour major group of protozoaChapter 7. Protists

아메바류아메바류편모충류편모충류

섬모충류섬모충류 포자충류포자충류

Chapter 7. Protists

1) Amoeba - no definite form -> changing shape by pseudopodia for move and feed

- Mastigamoeba : both flagella and pseudopodia

- no photosynthesis -> heterotrophic nutrition

- reproduction by mitosis, some by sexual reproduction

- Foraminifera(유공충류) : form hardened, shell-like casing(tests, 피각)

-> 바다 바닥의 두꺼운 침전층 형성(유전형성시기에 생존)

-> 유전 개발의 깊이 표식 기준

White cliffs(유공층잔해로 형성)

White cliffs(유공층잔해로 형성)

- Heliozoa(태양충류) : freshwater amoeba, Radiolaria(방산충류) : 해양침전물 형성원인류

- pathogenic species are very rare, but

-> Entamoeba histolyca : amoeiasis(아메바증)유발 -> 장궤양 및 통증 유발

-> Acantamoeba : contact lense 사용자의 각막염증 유발

-> humidifier fever : allergic reaction caused by amoeba

2) Flagellates (편모충류)

- long, hair-like flagella -> 9+2 arrangement of microtubule

- most fundamental protists -> combination of good chemical talents and diversity

Chapter 7. Protists

Chapter 7. Protists

Euglena : freshwater microbe, nucleus, two flagellates

- very flexible nutrient requirements

- in sunlight : fully autotrophic by photosynthesis

- in dark : lose photosynthetic pigments and become heterotrophic mode

- return to light : resynthesizes photosynthetic pigments -> become autotroph

- have eyespot sensing light (빛 감지 안점)

pelliclemitochondrionGolgi body

ER

nucleus

eyespot shielding a light-sensitive receptor

long flagellum

contractile vacuole chloroplast

Chapter 7. Protists

☞ Pathogenic flagellates

- Trypanosoma brucei, Trypanosoma cruzi

-> african and south american sleeping sickness

Undulating membrane (fold of a pellicle, attached to part of flagellum)

free flagellum

mitochondrion

Golgi body

vacuolenucleusendoplasmic reticulum

Trypanosoma bruceiTrypanosoma brucei

Chapter 7. Protists

☞ Pathogenic flagellates

- Giardia lamblia : 야영자 도보자들의 설사병, 야생동물에 의한 오염된 물이 원인

- Trichomonas vaginalis : trichomoniasis(트리코모나스증)의 원인균

-> sexually transmitted disease over 2 million women per year

- Leishmania tropica : 걸프전 당시 사막파리에 의한 미국병사들 감염

Trichomonas vaginalisTrichomonas vaginalis

Chapter 7. Protists

3) Ciliates (섬모충류)

- extremely diverse heterotrophic protozoa

- size : 10μm ~ 3mm, 9+2 arranged hairlike cilia for movement

- Paramecium (집신벌레)

- two types of nuclei : macronuclei and one or more micronuclei

-> macronuclei : cellular metabolism and growth

-> micronuclei : cell division 의 중심역할

food vacuole

food residues being ejected

gullet cilia

trichocysts (“harpoons”)

contractile vacuole filled

micronucleusmacronucleus

contractile vacuole emptied

☞ Reproduction of Paramecium by sexual conjugation

Chapter 7. Protists

Chapter 7. Protists

4) Sporozoa (포자충류)

- at some stage in life cycle, develop a sporelike body

- all are parasites, cause serious diseases in human and animal

- Plamodium : cause malaria trasmitted by mosquito, over 300 million cases per year

merozoite

Chapter 7. Protists

☞ Toxoplasmosis (톡소플라스마증)

- blood disease acquired thru cat by Toxopalsma gondii

☞ Pneumocystis carnii

- most serious illness in AIDS patients

- over 50 % of all death associated with AIDS

- no particular symptom in healthy person

- during AIDS, immune system is suppressed

-> parasites multiply quickly and take up all air spaces

☞ Cyclospora caryetanensis

- 소화관 질병 유발, 나무딸기와 관련성

Toxopalsma gondiiToxopalsma gondii

Chapter 7. Protists

2. Other Protists- some protists reside in the boundary of classification btwn plant, microbes, animal

- algae is good example ->algae : “seaweeds” in Latin, meaning simple plant

- two general types of algae -> unicellular : microbes vs multicellular : seaweed

- unicellular algae : important relationship with society

-> phytoplankton(식물성플랑크톤) : 전형적 해양 단세포조류

-> generate most of molecular O2 by photosynthesis

-> produce over half of world’s organic matter -> important role of food chain

Chapter 7. Protists

1) Pyrrophyta (염색식물 division )- so-called fire-algae(화조류) because of bright red and orange pigments

- photosynthesis, encased in rigid walls

- all members are dinoflagellates(쌍편모조류)

-> first flagellum move forward, second whirls the cell on its axis (“dinos”) - some species are bioluminescent -> light up the sea in the night

- cause red tides by burst reproduction under warm and plentiful nutrients

-> produce poisonous toxin -> concentrate in sea shells -> 마비성 패류중독

dinoflagellatedinoflagellate

Chapter 7. Protists

2) Chrysophyta (황갈조식물 division )

- golden-brown or yellow-green algae, include diatoms(규조류)- diatoms are distinguished by delicate glasslike shells of silicon dioxide

-> major component of the phytoplankton -> roles in oceanic food chain

-> diatomaceous earth(규조토), resulting from accumulation of diatom shells

-> polishing, insulating, and filtering materials

-> some are toxic to animals

Chapter 7. Protists

3) Euglenophyta (유글레나식물 division )- 800 species are known, Euglena is most notable

- plantlike and animal-like

4) Chlorophyta (녹조식물, division)

- Chlamydomonas is well-studies

-> has complex life cycle => alteration of generation(세대교번)-> characteristic in multicellular green algae or complex plant

-> two forms of organisms : diploid and haploid

-> mature Chlamydomonas is single haploid cell

-> under normal environment, asexual reproduction

-> sexual process under environmental stress producing fused diploid zygote

Life cycle of ChlamydomonasLife cycle of Chlamydomonas

Chapter 7. Protists

5) Slime molds (점균류)- a collection of both plantlike and animal like microbes

-> plantlike : enclosed in cell walls composed largely of cellulose

-> animal like : have flagellated cells to move at some life cycle point

Dictyostelium discoideumDictyostelium discoideumplasmodiumplasmodium

Fruiting bodies of slime moldsFruiting bodies of slime molds

Life cycle of cellular slime moldsLife cycle of cellular slime molds