topic 3: algae (org. bio)

Ecological or functional group

A group of organisms classified by their role in the environment or similar function, not necessarily by ancestry

Primary endosymbiosis

When a eukaryotic cell engulfs a prokaryote, and the prokaryote becomes an organelle

Secondary endosymbiosis

When a eukaryotic cell engulfs another eukaryotic cell that already has chloroplasts

Haplodiplontic life cycle / Alternation of generations

A life cycle with both a multicellular haploid stage and a multicellular diploid stage

Dinoflagellates

• Mostly marine protists with two flagella; many are planktonic and some cause harmful algal blooms

• cause red tides

Diatoms

• Single-celled algae with glass-like silica cell walls

• 25% of global NPP

Brown algae

• marine algae including kelp

• this cell engulfed a green algae eukaryotic cell

Red algae

• deep in the ocean, their pigments absorb blu elight and reflect red light

• nori (sushi seaweed)

green algae

• closest relative to plants

• contain chlorophyll

• ex: volvox

Phycocolloid

A slimy substance extracted from algae used as a thickener or stabilizer, prevent drying out

What are algae?

Photosynthetic organisms that are not land plants

Are algae a monophyletic group?

No, algae are an ecological/functional group, not a clade.

Evidence for secondary endosymbiosis?

Extra plastid membranes and sometimes a relict nucleus (nucleomorph).

Which groups arose via secondary endosymbiosis?

Diatoms, brown algae, dinoflagellates