Lecture 4 animals (1)

Lecture 4 animals (1) - Protozoans 1 Protozoans define hard...

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Protozoans: 1. Protozoans define hard characterization -- there's vast diversity of protozoans, the number of protozoans rivals all other animals groups combined -- protozoans are found in lots of sizes, feeding patters, i.e. mutualistic, commensealistic, parasitic -- protozoans also contain a variety of different symmetries, including asymmmetry, radial symmetry and spherical symmetry 2. Protozoans appear to be simple, but they are as complex as any other animal -- in protozoans, a single cell is capable of all the functions that multicellular cell does, i.e feeding, digestion, locomotion -- possess organelles not found in metazoans, i.e. contractile vacuoles are only found in protozoans 3. Protozoans are ecologically and economically important -- primary producers and have large role in decomposition -- Human/animal health (malaria, sleeping sickness) Protozons are characterized by the type of locomotion they possess: 1. Ciliary motion: fastest protozoans, i.e. paramecium Cilia: hair-like outgrowths from body/cell wall, Fastest protozoans ( 720 cm/h 2. Flagellar motion: 1/10 of cilia speed Flagella: whip-like outgrowths from body/cell wall, 1/10 of ciliary speed (72 cm/h) -- on organism can have many flagella, but they all have to come from the same end of the cell 3. Amoeboid Motion: very slow Pseudopodia : a free-form projection of the body or cell surface -- extremely slow Ciliary Locomotion: -- function of cilia is to move water parallel to cell surface -- cilia prevents for directed movement and at the same time it creates water current directed to the cytostome (mouth) -- Cilia also prevents stagnant layer of water from accumulating around body -- cilia brings fresh water towards animals surface and excretes waste from cell stationary cell will use up all of water close to cell, cilia brings fresh water for stationary cells -- movement of organism is achieved by coordinated beating of cilia ( Metachronal Beating ) -- cilia beats o bliquely (at an angle ), so organism moves in spiral path -- when cilia encounters a barrier, it can perform avoidance reaction and change its direction -- -- Protista does not include all descendents from common ancestor = paraphyletic -- have many nuclei, but no single nuclei controls the cytoplasm, therefore unicellular -- digestion = food vacuoles, water regulation = contractile vacuoles
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-- reproduction is through binary fission, -- protists live in aqueous environments (marine or freshwater) -- Cilia beats 1 way and animal moves the opposite way 1. Power stroke: Rigid/stiffened cilia - moves from Left to Right,
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Lecture 4 animals (1) - Protozoans 1 Protozoans define hard...

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