Kingdom Protista

Kingdom Protista

Endosymbiosis

Theory believed to explain origin of eukaryotes and complex organelles like mitochondria & chloroplast

19.1 Introduction to Protists

Protists

Large prokaryotes engulfed a smaller prokaryote and lived symbiotically

Eventually evolved into a single organism

Chapter 19

Protists

All protists are eukaryotes.

19.1 Introduction to Protists

Protists

Some reproduce asexually by mitosis while others exchange genetic material.

Most are single celled First Eukaryotes on Earth Must have moisture

Chapter 19

Classifying Protists

Some scientists classify protists by their methods of obtaining nutrition.

Protists

Animal-like protists- Heterotroph

Plantlike protists- Autotroph

Funguslike protists- Saprotroph

19.1 Introduction to Protists

Chapter 19

Animal-like protists

• Heterotrophs• Single-celled• Eat algea, bacteria or other protists• “protozoans” = “pre” animals• 4 phyla (groups) based on mode of movement

Phylum Zoomastigina - flagellates

Trypanasoma: Giardia:Causes African sleeping sickness Causes intestinal infections

More Zoomastigina – Trichonympha – digests cellulose in termites

Phylum Sarcodina

• Move and feed through use of pseudopods

• Pseudopod – temporary projection of the cytoplasm

• i.e. Amoebas• When feeding, they surround food

and bring into cell in the form of a food vacuole by endocytosis

Phylum Ciliophora - ciliates• Use cilia for feeding and

movement• Cilia: hair-like projections that

flow back and forth like ores• Example: Paramecium• Contain macro (working copy)

and micronucleus (reserve copy of genetic info)

• Contactile vacuole removes excess water

• Reproduce by conjugation or binary fission

Ciliophora • Stentor• Largest known protozoan

Phylum Apicomplexa - sporozoans• Parasites• Move through blood of host organisms• Reproduce through spores• Ex: Plasmodium causes malaria.

Malaria sporozoite

Protozoa Structures • Pellicle – A rigid, but flexible structure of

microtubules that underlies the plasma membrane of many protozoans.

• Trichocysts – Some pellicular structures are used for protection. These “threads” cover the body of the protozoan.

Protists and Disease• Malaria – effects 300-500 million

people– Caused by the sporozoan

Plasmodium carried by mosquitoe• African sleeping sickness

– Caused by zooflagellate Trypanosoma

– Spread by the bite of the Tsetse fly• Amoebic dysentery

– Caused by amoeba in contaminated water

• Giardia– Intestinal infection; ingested from

infected waters

Plant-like ProtistsAKA: Algae

• Autotrophs• phytoplankton• Contain chlorophyll and other pigments• Produce 70% of earth’s oxygen• 6 phyla• Classified by pigment and structure

Algae• Green• Brown• Red• Dinoflagellates• Diatom• Euglenoid

Phylum Chlorophyta – Green Algae

• Contain chlorophyll as main pigment

Phylum Phaeophyta – Brown algae• Contain brown photosynthetic pigment• Include Kelp

Phylum Rodophyta – red algae• Contain red photosynthetic pigments• Carrageenan used in ice cream and

other yummy foods

Phylum Pyrrophyta - Dinoflagellates •Two

flagella around “equator” to spin

•One flagellum on end to propel forward

Cause red tides

Phylum Bacillariophyta - Diatoms

• Pill-box shape

• Hard outer shell

Diatoms• Diatomaceous earth• You brush your teeth with these

Phylum Euglenozoa (Euglenoids)• Swim with flagella• Live in lakes and streams• Can also be heterotrophs!• Use eye-spot to detect light• Can reproduce asexually

through binary fission• Example: euglena

Fungus-like Protists• Feed on decaying matter and absorb nutrients-

saprophyte• Cell wall with cellulose• Slime molds and Water molds/Downy Mildews

Phylum Acrasiomycota – cellular slime molds

Water Molds and Downy Mildews