Alga - singular, Algae - plural
Algae orders are highly specialized and distinct. Classifications change frequently.
Originally classification was on color and form only.
1800's light microscopy
1935 - 1980 16 different major classification schemes published
1960's Electron microscopy - ultrastructure
1. Mitosis and Cytokinesis
2. Flagellar apparatus
3. Cell coverings and scales
1980's Molecular level
1. PCR
2. Gene mapping
Time line
Estimates:
3.5 - 3.7 billion yrs ago, first cyanobacteria CO2 = 10% of atmosphere
2004 CO2 concentration = .038% or 380 ppm
As blue-green algae multiplied more O2 released into atmosphere that acted as a toxin to anaerobic life forms and lead to the appearance of eukaryotes. (part of Gaia Hypothesis)
The earliest multi-celled organism was a red algae or Rhodophyta (about 1 billion years old)
Taxonomy:
Division or Phylum for algae
(Kingdom)-- algae {Eukaryotes with the Protista, prokaryotes with Monerans}
Division
Class
Order
Family
Genus
Species
Example:
Division: Chlorophyte
Class: Ulvophyceae
Order: Ulvales
Family: Ulvaceae
Genus: Ulva
Species: lactuca
Common name: "sea lettuce"
Major Divisions:
Prokaryotes
All three are different names for the same organism (Blue-Green algae)
Division Rhodophyta (Red Algae)
Division Chlorophyta (Green Algae)
3 membranes around chloroplast
Unicellular flagellated organisms
Division Dinophyta - (dinoflagellates) (red tides/ Pfisteria)
Division Euglenophyta
Division Cryptophyta
PRIMARY FACTORS
all algae have Chlorophyll a a strong indication that there is a common alga ancestor
Chlorophyll a absorbs light between 400 - 700 nm
PAR- Photosynthetic Active Radiation (the light radiation of absorption)
wavelength = 400 nm - blue ----------------------------------- 700 nm - red
Accessory pigments- extra pigments to help chlorophyll a attract and absorb more efficiently
Pigments
Blue Green- (Cyanobacteria)
Cell structure:
Cyanobacteria- Contain Thylakoids - Photosynthetic pigment also in chloroplasts of other algae
Cell divides by furrowing- pinch off in middle and divide up organelles and split nucleus and chloroplast.
Alga bodies are called THALLUS
They take several forms:
which fuse to
form zygotes
Which then form thallus