Rhodophyta Flashcards
Majority of seaweeds are what type of algae
Red- more diverse than all other seaweed groups combined
Where is red/ brown algae dominate
Where is green algae dominant
Tropical and temperate
Polar and sun polar
__________ algae are one of the oldest groups of eukaryotic algae
Red
Chloroplasts of red algae appear to have originated from ________ by ______ endosymbiosis
Cyanobacteria
Primary
The major feature of a red algal cell are a chloroplast with _________ per band and only _____ chloroplast membranes
One thylakoid
2
What phylum have Floridean starch grains in cytoplasm
Red algae
Rhodophyta
Floridian starch grains
Long term storage product
Similar to amylopectin of higher plants, is highly branched and resembles Cyanobacteria starch
(No amylose like green algae)
Starch grains cluster around ________ of chloroplast in primitive red algae
Pyrenoid body
Thylakoid structures in Rhodophyta
Unstacked (simile to Cyanobacteria)
Phycobilisomes occur on the surface of the thylakoids
Chlorophyll a found in the chloroplasts and carotenoids: zeaxanthin
Accessory pigments: phycoerythrin: absorption in green and reflect red
Chromatic variation
Colour of red algae varies depending on where it grows
-orange/red light (long wavelength)->phycocyanins
-green light (short wavelength)->phycoerythrin
Species may be yellow-green when growing in the intertidal zone or deep purple when growing 10-20m below the surface (Subtidal zone)
Ratio of phycoerythrin to chlorophyll is much greater at low light intensisties
Sulfated polysaccharides
Typical for many red algae
-major constituents of agar (less sulfated) and carrageenans (more sulfated)-> extracted for commercial uses
Agar
Mainly obtained commercially from species Gelidium, pterocladia
-collected by diving, dragging and raking at low tide
-agar extracted under pressure in autoclave, decolonized and deodorized with activated charcoal, filtered-> food and drug
Calcification of Rhodophyta
-Coralline red algae=heavily calcified walls
-helps establish fossil record
-crystalline calcite (forms of CaCO3)
-possible that CaCO3 formation helps hard best nutrients
Red algae were probably the first __________
Why?
Multicellular organisms
-conspired of cellulosic microfibril network+amorphous matrix of sulphated polysaccharide polymers and mucigel
-sulfated polysaccharide polymers create a multicellular organism by hankering every cell in a gel mass
-mucigels expand with hydration and help cell dispersal and attachment
Diffuse
Cell division is not localized
Early in multicellular red algae