Green Algae (Phylum Chlorophyta)

Endosymbiosis Background

  • Primary endosymbiosis: a eukaryotic host cell engulfs cyanobacteria to make chloroplasts (plastids)

    • Gave rise to Green and Red Algae

  • Secondary endosymbiosis: a eukaryotic cell engulfs another eukaryotic cell that already contains plastids

    • Gave rise to Brown Algae, Diatoms, Dinoflagellates, etc.

Class Chlorophyceae

All Chlorophytes: Live in Freshwater, Have Zygotic Life Cycles, and Flagellated Cells

Chlamydomonas - Most primitive green algae

  • Form: Unicellular

  • Structures:

    • 2 Flagella

    • Light-sensing eyespot

    • Pyrenoid (a derived trait used to store starches)

  • Life Cycle: Isogamous; Also includes (before the making of the Zygote):

    • Plasmogamy: fusion of cytoplasm during fertilization.

    • Karyogamy: fusion of nuclei to form the zygote.

    • Zygospore = Zygote resting stage, Zoospore = Flagellated Gametes

Volvox - Motile, Colonial Green Algae

  • Form: Colony of individual biflagellate protist

  • Life Cycle: Oogamous, Have inducer hormones to attract other colonies

    • Asexual Reproduction: Reproduce by forming daughter colonies inside the parent colony, then breaking off at maturity.

    • Sexual Reproduction: Inducer chemicals that attract colonies to mate; there are sperm (gametes) and eggs produced within colonies.

Hydrodictyon - Sessile “Water Net”

  • Form: Colonial, Tube-like (siphonous), Net-like structure (each link is a cell)

  • Life Cycle: Isogamous, Asexual & Sexual Reproduction

Oedogonium - Filamentous Chlorophyte

  • Form: Filamentous

  • Life Cycle: Oogamy.

    • Has Oogonium Structure: The egg-producing structure

Fristhella - Thallus Green Algae

  • Form: Branched Parenchymatous

  • Structures:

    • Rhizoid - to anchor

    • Plasmodesmata - a derived trait used for cell to cell communication

Class Ulvophyceae

All Ulvophytes: Marine/Freshwater, Thallus (Flat multicellular body) or Siphonous (One giant tube-like cell)

Acetabularia - “Mermaids Wine Glass”

  • Form: Siphonous

  • Life Cycle: Gametic

  • Structures:

    • Coenocytic - Multinucleate Cell

    • three-part morphology (rhizoid, stalk, cap)

  • Hemmerling Study: Proves the nucleus is at the base, not the stalk.

Order Siphonales

  • Caulerpa – (Monster of the sea)

    • Native to the black sea.

    • Invasive species that’s banned in US

  • Halimeda - Has calcium carbonate in it which contributes to the white sand beaches, produces toxins

  • Penicillus - Penicillin

Cladophora

  • Form: Branched Filamentous

  • Life Cycle: Anisogamy

    • Zygotic - Freshwater

    • Alt. of Generation - Marine

Ulva - “Sea Lettuce”

  • Form: Thallus

  • Life Cycle: Anisogamy, Alternation of Generation

    • Spores in this cycle are called ZOHO spores (flagellated spores)