Episodes of life
- Prokaryotes
a. 3.5 B yrs ago - Oxygen production started with evolution of photosynthesis
a. 2.5 B yrs ago—stromatolites - Single celled eukaryrotes
a. Protists
b. 1.8 B yrs ago - Multicellular eukaryotes
a. 1 B yrs ago
b. [Protista]: plantae, fungi, animalia
Origin of eukaryotic cells
- Inward folds of PM of a prokaryotic cell to make the nucleus
- Endosymbiosis—incorporation of mitochondria and chloroplasts into cell
algal protist
unicellular, colonial, multicellular
a. Green algae ancestor of land plants
fungal protist (not related to fungi)
a. No cell walls or have cell walls made of cellulose not chitin
b. Fungal protist, protozoa, algae do not form natural groups
c. Slime molds: heterotrophic protist
i. Land organisms that eat microorganisms in dying plant or animal matter
1. Can be multinucleate mass of protoplasm (plasmodial slime molds)
2. Can be amoeba-like uninucleate cells (cellular slime molds)
Oomycota
i. Unicellular to filamentous forms
ii. Reproduce sexually or by oogamy (female big, sperm small and plentiful)
1. Zygote is thick walled oospore
iii. Downy mildew pathogen
1. Threatened grapes and came from USA
2. Cure—copper sulfate
iv. Damping off disease
1. Affects greenhouses
characteristics of algae
- Lack leaves, roots, flowers, seeds, may have specialized tissue
- Photoautotrophic
- Different groups have different pigments or chloroplast structure (endosymbiotic origins)
- Eat plankton
- Coral animals eat unicellular algae zooxanthellae that live within their tissues
o Stress can eject the algae
phytoplankton
o Algae and cyanobacteria in water column
o Energy source for most marine species
o Important in chemical cycling—CO2 to sugar
o Fixing CO2 into CaCO3 in scales covering their bodies
Algal blooms caused by
warm water, low salinity, and high nutrient content
o Kill fish or food poisoning in humans and animals
o Algae produce toxin
food chains
commercial use
- Important macronutrients N, P K
- 12-8-10
- Fertilizer
- Eat as vegetables or food prep
- High protein, mineral, vitamin
- Manufacturing products—thicken or stabilize
dinoflagellates
- Unicellular biflagellate
- Cell membrane stiff cellulose plates
- Chlorophyll a, c and carotenoid peridinin to protect chlorophyll
- Flagella beat in 2 grooves
- Store starch
- Neurotoxic shellfish poisoning
o Eating shellfish that have brevotoxins from dinoflagellate
Euglenoids
- Unicellular, NO cell wall
- Chloroplast a b and store paramylon other than starch
- Contractile vaculoles allows cells to eliminate excess water
- Divide as they swim (asexual)
Diatoms
- Two part cell walls made of silica and cellulose
- Bilateral symmetry—pennate diatom
- Radial symmetry—centric diatom
- Chlorophyll a and c and fucoxanthin
(Phaeophyta) Brown algae
- Seedweed
- Thallus body form branched filaments
- Differentiated regions—stripe, blade, holdfast
- Airbladders to float
- Chlorophyll a and c and fucoxanthin like diatom (common origin)
reproduction
- Sporophyte (2n) is spore produing stage
o Give sporangia that release spores (n) by meiosis
Spores germinate produce gametophyte - Gametophyte is gamete producing stage
o Gives gametangia (antheridia and oogonia) that produce gametes
Fertilization follows and zygote grows into sporophyte
(rhodophyta) Red algae
- Multicellular seaweed
- Pigment form phycobilin—absorb green and blue light
- Chlorophyll a only
- Deposit CaCO3 in cell walls
- Coralline algae for coral reefs and tide pools
(Chlorophyta) Green algae
- Unicellular parenchymatous (tissue like)
- Aquatic
- Store starch in plastids
- Cell walls made of cellulose
Chlorophyceae largest group of green algae
o Closer to land plants than other class of green algae
o Glycolate oxidase in peroxisomes (photorespiration
o Cell division with phycoplast
Microtubules are horizontal
Ensure each daughter cell gets a nucleus
o Chlamydomonas
2 flagella and 1 chloroplast w/ a stigma (light perception)
Cell wall has no cellulose
Complex colonies
Held together by matrix and flagella beat individual
Colonies may be polar
* Stigmas may be longer on one end
Undergo mitosis
o Volvox
Some are reproductive
Polar, spins CW, moves to light
Divide by mitosis to make sphreroids
Sexual reproduction done by oogamy
Filamentous and parenchymatous species
Connected by plasmodesmata
Coleochaete
One thick discoid alga grows on surface of fresh water plants
Cytokinesis –in growth of cell wall and constriction of cell membrane
Phragmoplast at mitosis (assembly of microtubules and ER for anaphase and telophase to make cell plate)
Oogamous
* Zygote grows in oogonium on female parent
* No spore generation, only multicellular generation is haploid
* Antheridia are multicellular
o Chara
Grows in temperate lakes (branched apical growth)
Cytokinesis –in growth of cell wall and constriction of cell membrane
Phragmoplast at mitosis (assembly of microtubules and ER for anaphase and telophase to make cell plate)
Oogamous
* Zygote grows in oogonium on female parent
* No spore generation, only multicellular generation is haploid
Antheridia are multicellular
- Class Ulvophyceae
o Marine species
o Filamentous or flat thallus
o Ulva (sea lettuce)
