Chapter 21 Protists

What are protists? Eukaryotes that are not members of the plant, animal or fungi kingdoms They were the first eukaryotes (nucleus).

Characteristics of protists Most are unicellular Can be heterotrophic or autotrophic Most live in water (some live in soil, animals, …) ALL are eukaryotic (have a nucleus) Some can move – cilia, flagella, passive (float)

Characteristics of protists (cont.) Many reproduce by binary fission (asexual) Some can reproduce sexually and asexually Some exchange genetic information by conjugation (paramecium)

Type of protists Heterotrophic protists (amebas and paramecium) ▫Engulf and digest their food or absorb it from their environment

Ameba Lives in water Appear like blobs Moves using pseudopodia – “false feet” Reproduce by binary fission Ingests food by surrounding and engulfing it (endocytosis) Contractile vacuole – removes excess water Can cause amebic dysentery – diarrhea and stomach upset from drinking contaminated water

Ameba

Paramecium Live in water Move using cilia Exhibits avoidance behavior Reproduces asexually (binary fission) Reproduces sexually (conjugation) Ingests food through a mouth pore, gullet, then forms a food vacuole which fuse with lysosomes for digestion The outer membrane (pellicle) is rigid – the paramecium stays the same shape (like a shoe)

Paramecium

Types of protists Autotrophic (phytoplankton, kelp and euglena) ▫½ of the photosynthesis on earth is done by protists (producers) ▫Provide energy through photosynthesis to corals ▫ Provides shelter to other organisms (kelp – 60m) ▫Recycling waste

Euglena Live in water Have flagella for movement Use chloroplast for photosynthesis Can turn into heterotrophs if they are kept in the dark Has an eyespot used for sensing light and dark

Euglena

Protist diseases Parasite - an organism that lives on or in a host organism and causes harm to that organism Vector - an organism that can carry a parasite, and infect other organisms

DiseaseProtist Vector (carrier) SymptomsDetails Amebic Dysentery Entamoebawaterdiarrhea can get from tap water in some places Giardiasis ("beaver fever") Giardiawaterdiarrhea, vomiting don't drink water from streams African Sleeping Sickness Trypanosomatse tse fly uncontrolled sleepiness, confusion Only found in isolated areas lives in blood MalariaPlasmodium anopholes mosquito fever, chills, death can be treated with quinine lives in blood results in millions deaths per year ToxoplasmosisToxoplasmacats fetal death or brain damage pregnant women should avoid cat litter

Malaria Caused by the protist Plasmodium Carried by the Anopheles mosquito Found in hot, wet, tropical places The arrow points to the purplish colored protist (Plasmodium), the pinkish spheres are blood cells Anopheles mosquito taking a blood meal, this is how a human becomes infected with plasmodium and contracts Malaria

Malaria – life cycle

Other protist disease pictures This slide shows a blood smear of a person infected with trypanosoma. The protist is the purplish colored string-like things. They appear string-like due to a flagella. The reddish circles are blood cells. B = Protist, Giardia A = flagella