Cyanobacteria and Algae

Prokaryotes and Eukaryotes ProkaryotesEukaryotes “primitive nucleus”“true nucleus” Lack clear nucleus and other inclusions Clear nucleus and other inclusions All organisms with cells that lack a nucleus All organisms with cells that have a nucleus

Nutritional Requirements of Prokaryotes Methods of obtaining carbon Methods of obtaining carbon Autotroph (“self-feeding)  incorporate carbon into organic molecules from inorganic sources Autotroph (“self-feeding)  incorporate carbon into organic molecules from inorganic sources Heterotroph (“other feeding”)  derive carbon from breakdown of organic compounds Heterotroph (“other feeding”)  derive carbon from breakdown of organic compounds Methods of deriving energy Methods of deriving energy Chemotroph (“chemical feeding”)  obtain energy from catalyzing inorganic reactions Chemotroph (“chemical feeding”)  obtain energy from catalyzing inorganic reactions Phototroph (“light feeding”)  obtain energy by absorbing light photons Phototroph (“light feeding”)  obtain energy by absorbing light photons

Symbiotic Relationships Between Prokaryotes & Plants Rhizobium lives in soil Rhizobium lives in soil Synthesizes enzyme nitrogenase which converts unusable N 2 to plant-available ammonium (NH 4 + ) Synthesizes enzyme nitrogenase which converts unusable N 2 to plant-available ammonium (NH 4 + ) Forms mutualistic relationship with legumes within root nodules Forms mutualistic relationship with legumes within root nodules Plant → carbohydrates & protection Plant → carbohydrates & protection Bacterium → nitrogenase & other enzymes Bacterium → nitrogenase & other enzymes Both benefit from supply of fixed nitrogen Both benefit from supply of fixed nitrogen

Cyanobacteria “blue green algae” Photosynthetic Photosynthetic chlorophyll a, phycobilins chlorophyll a, phycobilins fix nitrogen fix nitrogen

Symbiotic Relationships Between Prokaryotes & Plants Other examples of symbiotic nitrogen fixing Bacteria Other examples of symbiotic nitrogen fixing Bacteria Frankia – within cells of root nodules of alders Frankia – within cells of root nodules of alders Anabaena – association with water fern, Azolla Anabaena – association with water fern, Azolla Nostoc – invades cavities in gametophytes of hornworts & cycads Nostoc – invades cavities in gametophytes of hornworts & cycads

Figure 17.11

Photosynthetic Protists “Algae”

Algae = Photosynthetic Protists Variety of life histories, body forms, ecological roles Variety of life histories, body forms, ecological roles Often named for distinctive colors Often named for distinctive colors Unicellular, colonial, multicellular Unicellular, colonial, multicellular

Phylum Chlorophyta “green algae” Unicellular, colonial, multicellular Unicellular, colonial, multicellular Most found in freshwater, also some in shallow marine habitats Most found in freshwater, also some in shallow marine habitats Pigments: chlorophyll a & b, carotenoid Pigments: chlorophyll a & b, carotenoid Food stored as starch Food stored as starch Cellulose cell walls Cellulose cell walls

Green Algae (a) (b) (c) 50 µm

Algal Reproduction Zygotic Zygotic diploid phase of life cycle is single-celled zygote diploid phase of life cycle is single-celled zygote Examples: Volvox, green algae, Chlamydomonas Examples: Volvox, green algae, Chlamydomonas Gametic Gametic Multicellular sporophytes Multicellular sporophytes haploid phase of life cycle is single-celled gamete haploid phase of life cycle is single-celled gamete Examples: some brown algae like Cystoseira Examples: some brown algae like Cystoseira Sporic Sporic multicellular gametophytes & sporophytes multicellular gametophytes & sporophytes Examples: Ectocarpus, Ulva (isomorphic), Laminaria (heteromorphic) Examples: Ectocarpus, Ulva (isomorphic), Laminaria (heteromorphic)

Zygotic l.h found commonly in green algae Gametic l.h. found in some Brown algae, especially rockweeds (Fucus, Pelvetia, Cystoseira) Sporic l.h. found in kelps, green algae, land plants

Zygotic Life Cycles Chlamydomonas Figure 18.

Ulothrix Life Cycle Figure 18.

Spirogyra Sexual Reproduction

Phylum Chromophyta (Stramenopiles) All have 2 unequally sized flagella (hairy & smooth) All have 2 unequally sized flagella (hairy & smooth) Photosynthetic ones include: Photosynthetic ones include: Chrysophyceae (golden algae) Chrysophyceae (golden algae) Bacillariophyceae (diatoms) Bacillariophyceae (diatoms) Phaeophyceae (brown algae) Phaeophyceae (brown algae)

Chrysophyceae “golden algae” Carotenoid pigments Carotenoid pigments Usually biflagellated Usually biflagellated Most unicellular, some colonial Most unicellular, some colonial Cell wall of cellulose Cell wall of cellulose Figure µm

Bacillariophyceae “diatoms” Unicellular algae with silica tests (cell wall) Unicellular algae with silica tests (cell wall) Important phytoplankton Important phytoplankton Contain chl. a & c, fucoxanthin Contain chl. a & c, fucoxanthin 3 µm

Reproduction in Diatoms

Phaeophyceae “brown algae” abundant in cool, shallow marine waters abundant in cool, shallow marine waters Largest algae, multicellular thallus Largest algae, multicellular thallus Life history sporic or gametic Life history sporic or gametic More Chlorophylls a & c, fucoxanthin More Chlorophylls a & c, fucoxanthin Carbohydrates can move through sieve elements & be stored (“mannitol”) Carbohydrates can move through sieve elements & be stored (“mannitol”) Cell wall of cellulose & algin Cell wall of cellulose & algin Blade Stipe Holdfast

Figure 18. Gametic (film)

Sporic Life Cycle

Phylum Rhodophyta “red algae” Widespread Widespread Shallow to deep water Shallow to deep water Warm to cool water Warm to cool water Chlorophyl a, phycobilins Chlorophyl a, phycobilins complex life cycle involving three types of thallus structures (“triphasic life cycle”) complex life cycle involving three types of thallus structures (“triphasic life cycle”) Cell wall of cellulose, agar or carrageenan Cell wall of cellulose, agar or carrageenan. (b) (c)

Figure 18. Triphasic Life Cycle

Phylum Euglenophyta “euglena” “mixotroph”, contains chlorophyll a & b “mixotroph”, contains chlorophyll a & b No cell wall No cell wall Contains eyespot Contains eyespot Lack cell wall Lack cell wall

Phylum Dinophyta “dinoflagellates” Unicellular Unicellular Contain two flagella. Contain two flagella. 1 trails from the cell 1 trails from the cell 1 encircles the cell 1 encircles the cell disc-shaped chloroplasts with xanthophyll pigments disc-shaped chloroplasts with xanthophyll pigments Many with tiny projectiles Many with tiny projectiles Many produce toxins (Red Tides) Many produce toxins (Red Tides)

Dinoflagellates

Ecological & Economic Importance Phytoplankton Phytoplankton Base of aquatic food chains Base of aquatic food chains Produce about 4x food as earth’s crops Produce about 4x food as earth’s crops Help build tropical reefs Help build tropical reefs Coralline green & red algae Coralline green & red algae Medicine, food, and fertilizer Medicine, food, and fertilizer Uses of algal cell walls Uses of algal cell walls diatomite for filtering, bulking, abrasive diatomite for filtering, bulking, abrasive agar as culture medium, gel electrophoresis & in baking agar as culture medium, gel electrophoresis & in baking carrageenan used as stabilizer carrageenan used as stabilizer algin used to absorb water & as additive algin used to absorb water & as additive

Kelp movie Kelp movie