Week 2, Session 2 Chapter 28Supplemental InstructionIowa State UniversityLeader: KelseyCourse: Bio 211 (5)Instructor: Dr. HolscherDate: 9-1-09Excavata- Diplomonadso 2 equal-sized nucleio multiple flagellao many are parasitic- Parabasalidso include the trichomonadso 4 flagellao undulating membrane- Euglenozoanso very diverseo contain a spiral or crystalline rod of unknown function inside their flagellao include kinetoplastids and euglenids Kinetoplastids- have a single, large mitochondrion that contains an organized mass of DNA calleda kinetoplast- include free-living aquatic and terrestrial species as well as parasitic species Euglenids- have one or two flagella contained in a pocket at the end of the cell- most familiar member is EuglenaChromalveolata- Alveolateso have membrane-bound sacs (alveoli) just under the plasma membraneo include dinoflagellates, apicomplexans, and ciliates Dinoflagellates- abundant components of marine and freshwater phytoplankton- spin as they move through the water- most are unicellular- rapid reproduction can cause “red tides”o toxins may be fatal to fish and humanso molluscs may accumulate toxins- some species are bioluminescent Apicomplexans- all are parasites of animals- spread through infective cells called sprozoites- most have a complex life cycle that require two or more host species Ciliates- use cilia to move and feed- have both macronuclei and micronuclei- reproduce by binary fission- genetic variation results from conjugationSupplemental Instruction1060 Hixson-Lied Student Success Center v 294-6624 v www.si.iastate.edu- Stramenopileso have a “hairy” and “smooth” flagellumo include diatoms, golden algae, brown algae, and oomycetes Diatoms- unicellular algae that have a glass-like wall of hydrated silica- highly diverse- major component of plankton- form diatomaceous earth golden algae- named for their color- biflagellated- photosynthetic- most are unicellular brown algae- all are multicellular, most are marine- includes seaweeds oomycetes- water molds, water rusts, downy mildews- once considered to be fungi- acquire nutrients mainly as decomposers or parasitesRhizaria- Foraminiferans (Forams)o named for their porous shells, called testso pseudopodia extend through their pores in tests - Radiolarianso tests fused into a delicate piece of silicao pseudopodia radiate from the central bodyArchaeplastida- red algae (rhodophytes)o most are reddish due to the accessory pigment phycoerythrin, which masks chlorophyll- green algaeo contains chloroplasts o closely related to land plantso include chlorophytes and chlorophyceans- Chlorophytes- most live in freshwater, some are marine- others live in soil, as symbionts in lichens, or in snowUnikonta- Amoebozoanso have lobe-shaped, rather than thread-like pseudopodia o include the slime molds, gymnamoebas, entamoebaso slime molds slime molds (mycetozoans)- once thought to be a fungi- include plasmodial and cellular slime moldso plasmodial slime molds brightly pigmented (yellow or orange) form a mass called a plasmodiumo cellular slime mold the feeding stage of the life cycle consists of solitary cells that function individually when food is depleted, cells form an aggregate that function as a unit cells remain separated by their membraneso gymnamoebas unicellular found in soil and freshwater/marine environments actively seek and consume bacteria and other protistso entamoebas parasites of vertebrates and invertebrates Entamoeba histolytica causes amebic dysentery and kills 100,000 per year- Opisthokontso nucleariidso fungio choanoflagellateso animalsProtists1. List four characteristics of protists:- most are unicellular- most live in aquatic environments- all are eukaryotes- nutritionally diverse2. Describe the three modes of nutrition in protists:Photoautotrophs Heterotrophs MixotrophsUse chloroplasts Absorb organic molecules, ingest large food particlesCombine photosynthesis and heterotrophic nutrition3. True or false: all protists reproduce asexually. ___False_______4. In your own words, describe endosymbiosis: One lineage acquired an additional endosymbiont that evolved into plastids– Gave rise to red algae and green algae Red algae and green algae underwent secondary
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