Kingdom Protista

Kingdom Protista

Diversity of Protists • Eukaryotic organisms that are not members of the kingdoms Plantae, Animalia, or Fungi

Diversity of Protists • 200,000 species • Single-celled to 100 meter-long seaweed • Eukaryotes • Type and arrangement of organelles varies

Diversity of Protists • 3 major categories • Animal-like protists (Protozoans) • Plant-like protists (algae) • Fungus-like protists

Protozoans • Animal-like protists • Heterotrophs • Feed on living organisms • Feed on dead organic matter • Can be motile or nonmotile

Protozoans • Types of protozoans • Classified according to method of movement

Protozoans • Types of protozoans: • Sarcodines • Zooflagellates • Ciliates • Sporozoans

Protozoans • Sarcodines • Move and “eat” using pseudopodia (amoeboid movement) • Cytoplasm-filled extensions of the plasma membrane • Blob-like (lack defined shape) • Lack a cell wall

Protozoans • Sarcodines Amoeba eating a Paramecium

Protozoans • Sarcodines Amoeba eating a Ciliate

Protozoans • Sarcodines • Live in marine and freshwater environments • Contain contractile vacuole which pumps water out of the cell to maintain homeostasis

Protozoans • Sarcodines

Protozoans • Sarcodines • Capture their food by surrounding it with pseudopods • Take it inside themselves by forming a food vacuole • Food is then digested

Protozoans • Sarcodines • Some have a hard outer shell made of calcium carbonate (Foraminiferans)

Protozoans • Sarcodines • Some have a hard outer shell made of silica (Heliozoans)

Protozoans • Sarcodines • Most reproduce asexually • One cell divides into 2 identical daughter cells

Protozoans • Sarcodines • Some form cysts to withstand unfavorable environmental conditions

Protozoans • Sarcodines • One species causes Amoebic dystentery • Live in pond and stream water (mainly in tropical parts of the world) • If live amoebas are swallowed with contaminated food or water they are destroyed by acid in stomach

Protozoans • Sarcodines • One species causes Amoebic dystentery • If cysts are swallowed, they survive the stomach and take up shop in intestines • Feed on intestinal wall, causing bleeding, diarrhea, and vomiting • If left untreated amoebas burrow completely through intestinal wall and enter bloodstream • Enter liver and other organs and form large cysts • Can be fatal

Protozoans • Zooflagellates • Move by whipping flagella

Protozoans • Zooflagellates • Mixotrica live in gut of termites • Termites cannot digest wood • Mixotrica living in digestive tract of termites can digest wood • Convert cellulose into carbohydrate termite and Mixotrica can use

Protozoans • Zooflagellates • Giardia live in intestines of animals • Beavers and muskrats are unaffected and help spread • Infections occur when people swallow contaminated water sources

Protozoans • Zooflagellates • Giardia live in intestines of animals • Humans who ingest Giardia get VERY, VERY SICK • Symptoms listed on the CDC website: • Diarrhea • Gas or flatulence often smelling of sulfur • Greasy stools that tend to float • Stomach cramps • Upset stomach or nausea.

Protozoans • Zooflagellates • Giardia live in intestines of animals • The CDC lists the following groups as being at the greatest risk: • International travelers • Backpackers, hikers, and campers who drink unfiltered, untreated water • Swimmers who swallow water while swimming in lakes, rivers, ponds, and streams • People who drink from shallow wells

Protozoans • Zooflagellates • Giardia live in intestines of animals • Mechanism that causes the symptoms is unknown • Symptoms can last 2-6 weeks • Infected persons can relapse at any time for the rest of their lives

Protozoans • Ciliates • Very diverse and large group • Move by beating cilia • Live in every aquatic habitat on the planet

Protozoans • Ciliates • Highly complex single-celled organisms

Protozoans • Ciliates • Highly complex single-celled organisms • Pellicle: tough outer membrane that protects the cell • Cilia: hair-like structures that project through the pellicle; beat in coordinated waves to produce motion • Micronucleus: nucleus responsible for sexual reproduction • Macronucleus: nucleus that controls all other functions in the cell

Protozoans • Ciliates • Highly complex single-celled organisms • Oral groove: cilia-lined opening in the pellicle into which food particles are swept • Gullet: structure in the cell that collects food particles and forms vacuoles around them • Food vacuole: membrane sack where food particles are broken down; nutrients are absorbed into cytoplasm

Protozoans • Ciliates • Highly complex single-celled organisms • Anal pore: opening through which wastes are expelled • Contractile vacuole: pumps excess water out of cell, back into hypotonic environment

Paramecium Contractile vacuole Pellicle Macronucleus Food vacuole Cilia Micronucleus Oral groove Anal pore Gullet

Protozoans • Ciliates • Reproduce asexually by mitosis and cytokinesis

Protozoans • Ciliates • If food is not plentiful can reproduce using a type of conjugation • 2 cells attach at oral grooves • Exchange copies of micronuclei • 2 cells detach and each divide asexually

Protozoans • Sporozoans • Can not move on their own • Must live in a nutrient-rich environment • All are parasitic

Protozoans • Sporozoans • Reproduce using spores • Reproductive cell (like an egg or sperm) that can produce a new organism without being fertilized

Protozoans • Sporozoans • Have a complex life cycle involving multiple hosts

Protozoans • Sporozoans • Have a complex life cycle involving multiple hosts (example: Plasmodium) • Causes malaria

Protozoans • Sporozoans • Have a complex life cycle involving multiple hosts (example: Plasmodium) • Lives part of its life in a mosquito and part in the blood of an animal

Diversity of Protists • 3 major categories • Animal-like protists (Protozoans) • Plant-like protists (algae) • Fungus-like protists

Kingdom Protista