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Scientist think that about 2 billion years ago, eukaryotes evolved and this led to an increase in the diversity of life on Earth. Eukaryotes are: more complex than prokaryotes. have more genes; allowing for greater cellular diversity in terms of size, shape, mobility, and specialized functions. The theory of endosymbiosis suggests that eukaryotic cells evolved from symbiotic relationships between two or more prokaryotic cells.
Although one prokaryotic cell engulfed a different, simpler prokaryotic cell, the engulfed cell survived and became part of the host cell.
Eukaryotic Evolution
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Chloroplasts and mitochondria: may have been freeliving prokaryotes engulfed by larger prokaryotes. comparison of chloroplasts, mitochondria, and prokaryotes shows:
similar types of membranes similar types of ribosomes each reproduces by binary fission each contains circular chromosomes gene sequences match
Scientists hypothesize that: the first multicellular organisms arose from colonies created by individual cells that divided genes within these cells contained instructions for some cells to become specialized with the passage of time, groups of cells developed different functions.
Eukaryotic Evolution
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Kingdom Protista
Representative Organisms: Algae, Amoeba, Spyrogyra, Paramecium
Cell Type: • Eukaryotic (has a nucleus and membranebound organelles)• most are unicellular (only one cell)
Methods of Reproduction:
Reproduction in protists is mostly asexual. The Protists do NOT develop complex sex organs and do NOT form embryos.
Asexual: All protists can produce asexually in a process called mitosis.Sexual: A few protists can produce sexually .
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Kingdom Protista
Characteristics:
Protists are singlecelled organisms but a few form multicellular colonies (the brown and red algae).
Protists have been classified into 3 groups ...
ALGAE (PlantLike) : Algae have photosynthetic pigments and photosynthesize
PROTOZOA (AnimalLike): "first animal", move & digest food internally
heterotrophic; consume prokaryotes, other protists or organic waste
SLIME MOULDS (FungusLike): slime moulds excrete digestive enzymes and absorb nutrients through their cell membrane (external digestion)
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Single Celled or Multicellular
Prokaryote or Eukaryote
"Feeds" off of others or Photosynthesis
Algaeplantlike protists
Protozoaanimallike protists
or Internal Digestion
External Digestion
Bacteria and Archaea
"Feeds" off of others or Photosynthesis
Plant
or Internal Digestion
External Digestion
Fungi
AnimalSlime Mouldfunguslike protists
Protists
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ALGAE plantlike protists Algae are plantlike protists that contain chlorophyll and photosynthesize Algae have cellulose cell walls. Algae have different pigments used to perform photosynthesis (they are autotrophs) Some algae move (are motile) using cilia. Algae are producers that start many food chains.
PlantLike Protists 1. Green Algae 2. Brown Algae 3. Red Algae 4. Diatoms major component of plankton5. Dinoflagellata have 2 flagella6. Golden Algae yellow/brown colour
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cilia flagella streaming pseudopods
PROTOZOA animallike protists Characteristics of Protozoa
They are heterotrophs (they must feed off other organisms to survive) They are unicellular and are "hunters" or "gatherers" (feed). Digestion in protozoans is intracellular (inside the cell). Protozoa lack cell walls. Many protozoa cause diseases (or are parasitic.) Most protozoa are motile (they can move) using either cilia, flagella or pseudopods
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PROTOZOA animallike protists
There are 4 phyla of protozoa
a) ciliates motile protozoa that use hair like projections called cilia to "swim" ie: Paramecium
b) flagellates motile protozoa that use a tail like projection called flagellum to "swim"
c) cercozoans motile protozoa that use "pseudopods" temporary cytoplasmic extensions that are used for feeding and movement (streaming) ie: Amoeba
d) sporozoans generally nonmotile but reproduce using spores
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SLIME MOULDS funguslike protistsFunguslike protists are called slime moulds.
Characteristics of Slime Moulds
Slime moulds secrete chemicals that digest food in their environment and then absorb the digested chemicals and so they are considered heterotrophs (feed off other organisms). Reproduction is asexual through fragmentation and the production of spores. slime moulds have cell walls made of cellulose (not the same kind as plants)
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Kingdom Protista
Biological Role:
Photoplankton are the basis of many food chains Algae produce O2 (photosynthesis)
Some work with termites (symbiosis) to help them digest wood fibre Used by humans to make: * fertilizer * icecream * paint * petroleum products * cosmetics * bioremediation in sediments
Connection to Human Health:
Some protozoa are parasites Plasmodium causes malaria Entamoeba hystolitica causes dysentery Trichomonas hominis help break down materials in human intestines Giardia lamblia 'beaver fever' nori seaweed used to wrap sushi rolls
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Kingdom Protista
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Kingdom Protista
Shape: The shapes of protists varies greatly
Size: · typically only 0.010.5 mm in size, · some protozoa grow as large as 5 cm