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Protists
Michelle Reilly, Cady Trvalik and Lisa Lucero
The Six Groups
Euglenozoa
Alveolata
Choanoflagella Brown Algae (Stramenopila)
Rhodophytakinetoplastid (Euglenozoa).
Chlorophyta
Stramenopila
All protists are aquatic - a few are terrestrial.
Three Types of ProtistsAnimal-like - protozoans• all heterotrophic, unicellular and mobile.
o divided by mobility/means of attaining food: pseudopods cilia flagella parasites
Fungi-like • all heterotrophic• contain long hyphae- like strands (bright in color)• can act as decomposers - break down dead organisms by releasing digestive
enzymes into organism.
Plant-like - all algae-Autotrophic capable of making their own food-contain chlorophyll and carry out photosynthesis-commonly called algae-four phyla: euglenophytes, chrysophytes, diatoms, dinoflagellates-accessory pigments help absorb light, give algae a variety of colors
Anatomy of a ProtistExtreme diversty: most cells contain:• nucleus or macronucleus: where the DNA is contained• micronuclei: smaller storages of DNA for everyday use.• cell membrane: pellicle, specialized to protists• cell walls: in plant-like protists• gullet: indentation on side of protist where food is swept• vacuoles: "bubbles" in cytoplasm to store/digest food • eyespot: helps protist to find light. • capsule: extra membrane.
Remember that the anatomy of a protist varies on whether it is animal-like, plant-like or fungus-like.
Digestion
Differs based on group:• Animal-like: heterotrophic
o use cilia, flagella and pseudopods to engulf food
o phagocytosis o vacuoles
• Fungus-like: heterotrophico phagocytosis of bacteria
• Plant-like: autotrophico photosynthesis o metabolic pathways plant-likeo chlorophyll A and C - not much B - and carotenoids
Excretion
• Excretion o excretion - the process of removing metabolic wastes
• Special excretory structures are absent in many unicellular organisms. o Excretion is accomplished by diffusion through cell membranes
• Freshwater Protozoans- in the amoeba and paramecium CO2, ammonia, and mineral salts diffuse through the cell membrane directly into the aquatic environment.
• Contractile vacuoles and osmosiso Contractile vacuole - pumps excess water out of the cell.o osmosis - the tendency of a fluid, usually water, to diffuse from
an area of high to low concentration.
Gas Exchange
• takes place directly at membrane - diffusiono diffiusion: unfacilitated movement of objects across a
membrane from area of high to low concentration• do not need specialized respiratory system
o autotrophs take in CO2, give off O2o heterotrophs take in O2, give off CO2
• diffusion keeps protists small - disadvantage
Circulation
• circulation- movement of materials within a cell or between parts of an organismo no circulatory system is needed for protists
• protists have a thin cell membrane • absorption occurs by diffusion & active transport
o active transport - the movement of ions or molecules across a cellular membrane from a lower to a higher concentration, requiring the consumption of energy.
• circulation occurs by cylosiso movement of cytoplasm
ReproductionGreat variation - most common in red.• Animal-like:
o asexual: binary/multiple fission, budding, encystmento sexual: isogamy, anisogamy, oogamy.
• Plant-like: o primarily asexual: binary fission, sporogony
• Fungus-like: o primarily sporogony, some binary fission
Plant and fungus-like protists often undergo an alteration of generations.
Support and Movement of Protist
Cilia-Used for movement-Hair like projections -May completely cover cell surface or may be clustered in a few rows or tufts-When bonded together can construct "leg-like" structures
Flagella -Long cellular for locomotion-Used for movement-"Hairy" numerous fine, hairlike projectionsvs. "Smooth" flagella
Lifestyle and Environment of a Protist
-They live in almost any environment that contains liquid water-Protist such as algae, are photosynthetic and are vital primary producers in ecosystems-Play big role in the ocean as part of the plankton-Healthy levels of algae will provide much of the oxygen for various animals-Algae are a food source small animals that live in water.-Diatoms may produce oxygen in our atmosphere-Amoeba, form the ‘predator’ stratum of the food chain-Many protozoans are parasitic on humans and our livestock-Some cause diseases such as malaria
Animal-like Protist: Paramecium
• covered with cilia - aid in motion and feeding• Dinidium: a Paramecium's worst nightmare• trychocists used for defense, hunting.• devoid of senses - can sense motion and do 360-degree turns• live in warm, stagnant water• reproduce sexually and asexually• can use electromagnetic radiation, biophotons, to
communicate
Fungi-like Protist : Slime Molds
• lives in moist soil, decaying plants, and trees.
• very bright appearance • single- celled organisms• go from single-celled to
unicellular, back to single-celled
• Form sporangiao sporangia - a cluster of
cells on top of a stalk
Plant-Like Protist: Euglena-contain chlorophyll and carry out photosynthesis-commonly called algae-four phyla: euglenophytes, chrysophytes, diatoms, dinoflagellates-accessory pigments help absorb light, give algae a variety of colors
-live in water-have 2 flagella for movement-use chlorplasts for photosynthesis, but can turn into heterotrophs if they are kept in the dark-has an eyespot used for sensing light and dark -pellicle - like a cell wall, helps maintain their shapes
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