Ch 17 Section 2

E. Green algae are the closest relatives of land plants Green algae are the most plant-like protist- They have chlorophyll a and b, store starch, and have cellulose cell walls, they have a variety of forms from unicellular to multicellular, they can live in fresh or salt water and have life cycles similar to plants. They can live symbiotically with fungus to form lichen. Examples: Chlamydomonas, Volvox, Spirogyra, Chlorella

Chlamydomonas

spirogyra Chorella- considered as a food source for space flight

17.3 Some heterotrophic protists were once classified as fungi A. Slime molds are unicellular and multicellular- two main types- both live in damp forests, both exist as a single amoeboid cells and as large mass that behave as a multicellular organism 1. plasmodial slime mold- consists of plasmodium which is a mass of thousands of diploid nuclei surrounded by a single cell membrane. Also called acellular slime mold. It moves along the forest floor eating bacteria and microorganisms. When it dries up, it forms a spore which is dormant until it germinates as a haploid cell, these fuse forming the acellular mass.

2. Cellular slime mold Retain their membranes throughout the life cycle. The cells exist as haploid amoebae. When food becomes scarce, it forms a slug like mass that moves toward light. It will produce a stalk that has spores. The spores will germinate to form haploid amoeba.

B. Water molds are decomposers and parasites Water molds are also called oomycetes. They are decomposers. They produce swimming spores. Water molds have cell walls made of cellulose. The best known water molds are those that ruin crops, like those that cause the downy mildew of grapes (Plasmopara viticola) and potato blight (Phytophthora infestans). Another well known water mold is Saprolegnia which forms cottony masses on fishes and other aquatic organisms.

17.4 Protozoa are diverse heterotrophic protists A. Several flagellated protozoa cause disease- They have flagella and are heterotrophs Examples- Trychonympha- lives in the intestines of termites and helps them digest wood. Trichomonas vaginalis- causes vaginitis- STD Giardia intestinalis- spread by contaminated water- causes severe diarrhea and cramping Trypanosoma brucei- causes African sleeping sickness Trypanosoma cruzci- causes Chagas disease Leishmania- causes Leishmaniasis

Trypanosomes trychonympha giardia

B. Amoeboid protozoa produce pseudopodia Pseudopods are cytoplasmic extensions in locomotion and ingestion in amoeboid protists. Examples- Amoeba proteus and Entamoeba histolytica (causes amoebic dysentery.) Foraminiferans- mostly marine species- shells made of calcium carbonate- many limestone and chalk formations are made of foram shells- they help identify deposits of oil and gas. Radiolarians- among the oldest protozoa- have shells made of silica

https://www.youtube.com/watch?v=cwBilJt0bIA

C. Ciliates are common protozoa with complex shells Ciliates- complex- mostly unicellular- cilia are used for motion and to sweep food items into the cell. Many are free living in water, but they may live attached to surfaces or in symbiosis with invertebrates. Examples- Paramecium D. Ampicomplexans- Nonmotile animal parasites Examples- Cryptosproridium- Toxoplasma gondii- Plasmodium- causes malaria

paramecium

Cryptosporidium(a type of ampicomplexan)

Toxoplasma gondii

plasmodium

https://www.youtube.com/watch?v=Ln69k7LyTsU