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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

Watch the video!

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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