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What defines clade Archaeplastida?
Chloroplasts derived by primary endosymbiosis
What is Primary Endosymbiosis of Chloroplasts
the original event where a eukaryotic cell engulfed a free-living prokaryote, which then evolved into a stable organelle - a chloroplast - within the host cell
What are the sub-groups in Archaeplastida
Rhodophyta - red algae
Glaucophyta - glaucophyte algae
Chlorophyta - green algaes
Streptophyta - streptophyte green algae & land plants
What type of algae is Polysiphonia?
Rhodophyta - red algae
Walk through the phases of the life cycle of Polysiphonia
- Meiosis
- Haploid tetraspores undergo mitosis to produce male & female gametophytes
- Male gametophyte has spermatangia (gametangia) that produce spermatia (gametes)
- Female gametophyte has carpogonia (gametangia) that produce eggs - the egg remains in the carpogonium attached to the gametophyte
- Fertilization
- Fertilized carpogonium becomes Cystocarp w/ zygote
- Zygote undergoes mitosis to become carposporophyte
- Carposporophyte blebs off as single celled carpospores
- Carpospores undergo mitosis to become tetrasporophytes
- Tetrasporophyte contains tetrasporangia, which undergo meiosis to produce tetraspores
Tetrasporophyte
multicellular diploid individual that produces haploid spores
Carposporophyte
multicellular diploid individual that produces diploid spores
Why are red algaes important?
Primary Producers
Able to use more of the wavelengths of light than other photosynthetic organisms
Deepest growing algae because of this - found at 820 ft of depth (300 ft deeper than any other photosynthates)
Provide some of the oldest direct evidence for sexual reproduction (Bangiomorpha ~1.2 BYA)
Coenocytic
Multiple/many organelles & nuclei contained in a common mass of cytoplasm and a shared cell membrane + wall
- Lacks septae between cells
ex. Caulerpa
Isomorphic
gametophyte and sporophyte stages look exactly the same
Heteromorphic
gametophyte and sporophyte stages look distinctly different