1. Domain Eukarya Kingdom Rhodophyta/Biliphyta? Phylum Rhodophyta

2. The Organism as a Unit of Life
Looking Back at Bio 115
The Organism as a Unit of Life
Cellular Structure (cell = unit of life)…one or many!
Metabolism = Homeostasis (PSN, Resp, N2fix, ferment, etc.)
Growth = irreversible change in size
Reproduction…failure = extinction
Acclimatization-short term responses = behavior
Adaptation-long term responses = evolution

3. Multicellular Animals
Shifting Kingdoms
Lumpers
Splitters
Plantae
Protista
Rhodophyta 2 3 5 6 8
Bacteria
Archaebacteria
Archezoans
Euglenoids
Chrysophytes
Green Algae
Brown Algae
Red algae
Slime Molds
True Fungi
Bryophytes
Tracheophytes
Protozoans
Myxozoans
Multicellular Animals

4. How Many Kingdoms? Extant 8 5 3 Extinct 2 Long Time with 1
Archaebacteria
Archezoans
Multicellular Animals
Protozoans
Green Algae
Bryophytes
Tracheophytes
Slime Molds
Myxozoans
True Fungi
Bacteria
Euglenoids
Chrysophytes
Brown Algae
Red algae 8 5 3
Extinct 2 1
Long Time with
Prokaryotes only
Original Cell

5. Rhodophyta Photosynthetic, mostly marine red algae Odd features
Body multicellular, supported by water, so simple thallus
Thallus attached to substrate by holdfast
Rarely pelagic (floating)
Chloroplasts have three membranes (secondary endosymbiont)
Photosynthetic pigments: chlorophyll a, phycoerythrin, phycocyanin…colors can be red, brown, purple, blue, green, blackish!
Storage materials: floridean starch in cytosol (-1,4-glycan)
Wall polysaccharides: cellulose and agar or carrageenan
No flagella, so centriole missing
Gametangia: spermatangia (male) and carpogonium (female)
Some species encrust with calcium carbonate…contribute to reefs
4000 species

6.
Compsopogon
Here are some of the example red algae some of these you should have observed in laboratory.
Caloglossa
Porphyridium
Callithamnion

7. Porphyridium Cell Wall Cell Membrane Mitochondrion Nucleus
Cell Wall
Cell Membrane
Mitochondrion
Nucleus
Stellate Chloroplast
Floridean Starch
Vacuole

8. Polysiphonia nigrescens Polysiphonia nigrescens
Polysiphonia nigrescens
Polysiphonia nigrescens
benthic (attached)
filamentous
common on New England rocky coast
2N tetrasporophyte
tetrasporangium
tetraspore (meiospore)

9. Polysiphonia nigrescens
Tetraspore (meiospore) germinates into isomorphic homothallic gametophyte (1N) thallus
Male branches near the tops of the plants produce spermatangia
Female branches near the bottom of the thallus produce carpogonia

10. Polysiphonia nigrescens
marine/algae/polysiphonia%20male.jpg
Polysiphonia nigrescens
Tetraspore (meiospore) germinates into isomorphic thallus
Male branches produce spermatangia releasing spermatia
Female branches produce carpogonium with trichogyne.
Trichogyne receives spermatium (no flagellum!)
spermatium
trichogyne

11. Polysiphonia nigrescens
The 2N zygote develops inside the cystocarp attached to the gametophyte (1N) thallus.
The cystocarps expand and mature into carposporangia
Carposporangia release diploid carpospores which then germinate into diploid tetrasporophytes.

12. Polysiphonia Life Cycle syngamy
Note: See previous slides for photo credits!
spermatangium
syngamy
gametes (produced by mitosis)
zygote (inside cystocarp)
Carposporophyte (inside cystocarp)
spermatium
(released to water) 1N 2N
carpogonium
carpospore
(released to water
settles to substrate
grows by mitosis)
trichogyne
cystocarp
Tetrasporophyte
Gametophyte isomorphic
homothallic
tetrasporangium
tetrasporocyte
tetraspore
(released to water
settles to substrate grows by mitosis)
meiosis