Cyanobacteria. THE FIRST ALGAE!!!!!. Evolution. Old 3.5 billion years Dominated as biogenic reefs During Proterozoic – Age of Bacteria (2.5 bya – 750 mya) they were wide spread Then multicellularity took over Cyanobacteria were first algae!. Cyanobacteria terminology.
THE FIRST ALGAE!!!!!
- Division Cyanophyta
- Cyanobacteria ‘formerly known as’ BlueGreen Algae
- Cyano = blue
- Bacteria – acknowledges that they are more closely related to prokaryotic bacteria than eukaryotic algae
Found in marine sediments and pelagic zone, freshwater lakes, soils,
Live in extreme environments – chemically and temperature.
2) Many – fix or convert atmospheric nitrogen into usable forms through Nitrogen Fixation when other forms are unavailable.
IMPORTANT because atmospheric N2 is unavailable to most living organisms because breaking the triple bond is difficult
- Pigments – chl a, phycobiliproteins
- phycocyanin * BlueGreen Color
- Storage – glycogen
- Cell Walls – amino acids, sugars
- OR - multiserate – not TRUE branching when trichomes are > 1 in rows
Trichome – row of cells
Mucilaginous sheath –
layer of mucilage outside of the cell wall.
Mucilaginous Sheath –
Function – protects cells from drying and involved in gliding.
Sheath is often colored:
Red = acidic
Blue = basic
Yellow/Brown = high salt
Heterocyst – thick walled cell, hollow looking. Larger than vegetative cells.
FUNCTION – provides the anerobic environment for N fixation.
CO2 + H2O ----------- CH2O (sugar) +O2
Electrons for PS1 come from PS2 which evolves oxygen (splitting of water)
2H2S + CO2 -------- CH2O +2S + H2O
H2S is the electron donor – so the reaction does not produce oxygen.
Eg. swimmers itch - Lygnbia
Releases chemicals causing dermatitis
- Hormogonia formation -
- Endospore / Akinete formation -
Hormogonia – short piece of trichome found in filaments. It detaches from parent filament and glides away
Fragmentation - fragmentation
Stromatolites – Shark Bay, W. Australia