Unicellular Eukaryotes (Protozoa/Protista) PDF

1 OUTLINE Animal Architecture 1. Levels of Organization 2. Organ Systems & Extracellular Components 3. Tissue Types 4. Body Plans 16 1. Acoelomate...

1 OUTLINE Animal Architecture 1. Levels of Organization 2. Organ Systems & Extracellular Components 3. Tissue Types 4. Body Plans 16 1. Acoelomate Ectoderm Endoderm - no true coelom (i.e. no body cavity) - region between ectoderm and gut occupied Flatworm - parenchyma (mesoderm) Mesoderm 2. Pseudocoelomate - possess a pseudocoel - “tube within a tube” arrangement - no peritoneum (i.e. no cellular Roundworm membrane derived from mesoderm) Pseudocoel Coelom 3. Coelomate - true coelom lined with peritoneum Earthworm 17 BODY PLANS 2. INTERNAL BODY ARCHITECTURE The coelom - body cavities within bilateral animals :ectoderm :endoderm :mesoderm :peritoneum parenchyma Keywords (mesoderm) 1. Acoelomate no coelom parenchyma pseudocoel 2. Pseudocoelomate pseudocoel no peritoneum coelom 3. Coelomate true coelom with peritoneum 18 BODY PLANS Chordates BILATERAL Arthropods Hemichordates Annelids Brachiopods Echinoderms Mollusks Bryozoans Nematodes Nemerteans Gastrotrichs Rotifers Flatworms Cnidarians Sponges Ancestral Metazoan Unicellular Eukaryotes 19 BODY PLANS Chordates COELOMATE Arthropods Hemichordates Annelids Brachiopods Echinoderms Mollusks Bryozoans Nematodes Nemerteans Gastrotrichs Rotifers ACOELOMATE Flatworms Cnidarians PSEUDOCOELOMATE Sponges Ancestral Metazoan Unicellular Eukaryotes 1 OUTLINE Unicellular Eukaryotes (Protozoa / Protista) 1. Introduction (Classification) 2. Locomotion 3. Nutrition, Digestion & Excretion 4. Osmoregulation 2 INTRODUCTION 1. Unicellular Eukaryotes defy tidy characterization -Vast Diversity rivals all other animal groups combined. -Array of sizes, feeding habits, physiological mechanisms. 2. Apparently Simple BUT actually as complex as any other animal. - i.e. a single cell capable of feeding/digesting, locomotion, “behaving” and reproducing - Possess organelles not generally found in metazoan cells 3. Ecologically and Economically Important - Primary producers and role in decomposition. - Human / animal health (Malaria, Chagas’) 3 INTRODUCTION Classification - Paraphyletic Group: most recent common ancestor is also the ancestor of animals, plants and fungi (hence the group does NOT include all the descendants of the common ancestor). Classification: Phylum Euglenozoa Amoebas (informal grouping) Class Euglenoidea Euglena Amoeba Class Trypanosomatidea Trypanosoma Phylum Ciliophora Paramecium Phylum Apicomplexa Class Coccidea Plasmodium 4 LOCOMOTION Three mechanisms of locomotion in Unicellular Eukaryotes 1. Ciliary motion Cilia: hair-like outgrowths from surface of cell. Fastest ciliates are up to 720 cm/h 5 LOCOMOTION Three mechanisms of locomotion in Unicellular Eukaryotes 2. Flagellar motion Flagella: whip-like outgrowths from surface of cell. Fastest flagellate - up to 72 cm/h 6 LOCOMOTION Three mechanisms of locomotion in Unicellular Eukaryotes 3. Amoeboid motion Pseudopodia: a free-form projection of the cell. 7 CILIARY LOCOMOTION A cilium propels water parallel to the surface of attachment - Provides the means for 'directed' movement - Prevents stagnant layer of water accumulating around body - Ciliary beating: a circular motion with 2 components: 1. Power Stroke 2. Recovery Stroke 8 CILIARY LOCOMOTION Ciliary Locomotion Body Wall Direction of animal Power Stroke: Stiffened cilia propel water parallel to cell surface Recovery Stroke: Cilia bends towards body to reduce resistance 9 CILIARY LOCOMOTION Ciliary Locomotion Body covered by distinct rows of cilia Movement of organism is achieved by coordinated beating of cilia Metachronal Beating 10 CILIARY LOCOMOTION - Cilia beat can reverse permitting avoidance reaction (B) Barrier or harmful stimulus - Cilia beat obliquely (i.e. at an angle), therefore organism moves in a spiral path 11 FLAGELLAR LOCOMOTION A flagellum propels water parallel to the main axis of the flagellum. Main axis of flagellum Flagellum - Bending in opposite directions along the flagellum to produce a wave action along the flagellum. Flagellate 12 FLAGELLAR LOCOMOTION Tractellum – a flagellum that draws water toward and over Direction of the cell body flagellum pulse In sessile flagellates: - Moves water across cell surface (i.e. prevents stagnation) Direction of movement - Bringsfood particles towards Direction of the organism water flow 13 FLAGELLAR LOCOMOTION Pulsellum – a flagellum that propels the cell in a cell body Direction of first direction. flagellum pulse In free-living flagellates: - Moves organism through water like a tadpole Direction of movement Direction of water flow 14 15 AMOEBOID LOCOMOTION Classic amoeboid locomotion uses cytoplasmic streaming & large blunt pseudopodia (lobopodia) 16 : Ectoplasm (gel-like, plasmagel) : Endoplasm (fluid state, plasmasol) 17 AMOEBOID LOCOMOTION : Ectoplasm (gel-like, plasmagel) : Endoplasm (fluid state, plasmasol) 1 Hyaline cap (ectoplasm, Gel) 2 Endoplasmic stream 3 Endoplasm fountains out to periphery actin microfilaments cross-link actin subunits polymerize Actin microfilaments Provide structure / 1 3 2 3 18 AMOEBOID LOCOMOTION Filopodia – much slimmer than lobopodia, contain only ectoplasm and lack a hyaline cap Filopodia of Chlamydophrys Reticulopodia – elaborate, extremely thin filaments that branch and coalesce repeatedly in highly complex patterns Reticulopodia of Globigerina