Botany 8.2 Eukaryotic Algae

are algae monophyletic or polyphyletic?

polyphyletic meaning they originated on multiple occasions

which clades of algae are more closely related to non-photosynthetic protozoa?

• eugleophyta

• dinophyta

what 3 sets of characteristics are used to identify algae?

1. photosynthetic pigments

2. storage products

3. cell covering

what are the photosynthetic storage products?

carbohydrates and lipids

why is it important for phytoplankton to have oil in their cells?

it helps reduce cell density and regulates buoyancy

cells coverings in prokaryotes vs eukaryotes

prokaryotes: peptidoglycan (protein and sugar cell wall)

eukaryotes:

1. membrane outermost layer

2. outer layer is cellulose embedded in some sort of matrix

3. calcium carbonate and silicone dioxide cell walls

plants vs algae

• plants have multicellular diploid embryos that are developmentally and nutritionally dependent on parent gametophyte tissue

• algae are aquatic photosynthetic autotrophs that are smaller and less complex than plants

filament growth

cells that share cell walls, they can either have one plane or multiple planes of cell division

true parenchyma growth

millions of cells with 3 planes of cell division

pseudoparenchyma growth

“false parenchyma”, where they have 2 planes of cell division, but they coil and weave onto each other so that it looks like they have 3 planes of cell division

siphonous growth

one giant cell with multiple nuclei

coenobia growth

unicellular colony with a fixed number of cells

coencytic growth

type of siphonous growth where the entire algae is one cell with multiple nuclei and plastids

advantages of asexual or sexual reproduction

asexual advantage - fast and no need for mate

sexual advantage - genetic recombination

cellular bisection

one cell goes through mitosis and cytokinesis to make 2 cells

zoospores

motile spores with flagella

aplanospores

non-motile spores; parents who can produce motile spores still produce non-motile spores

autospores

non-motile spores; non-motile parent producing non-motile spores

autocolony formation

parent colonies produce gametes with the same number of cells (ex.coenobia growth)

sexual reproduction varies in what?

• genetic recombination

• alternation of haploid and diploid phases

• meiosis

• fusion of haploid gametes

isogamy

equal sized gametes, both flagellated, and no gender only positive or negative

anisogamy

both flagellated, female is bigger than male

oogamy

female non-flagellated egg and male flagellated sperm

what is the most derived and most ancestral life cycle?

most derived - gametic

most ancestral - zygotic

describe gametic meiosis

• free-living diploid adults go through meiosis and create gametes

• haploid gametes either die or fuse

• haploid gametes fuse into one diploid gamete

• diploid gamete goes through mitosis and cytokinesis to form into free-living adults

describe zygotic meiosis

• free-living haploid adult goes through mitosis and cytokinesis to produce haploid gametes

• haploid gametes fuse with other strain of gametes to make a diploid zygote

• diploid zygote goes through meiosis to make haploid spores

isomorphic vs heteromorphic alternations of generations

isomorphic - gametophytes and sporophytes look identical

heteromorphic - gametophytes and sporophytes look different

describe sporic meiosis

• free-living haploid gametophyte go through mitosis and cytokinesis to creates haploid gametes

• haploid gametes fuse to create diploid zygote

• diploid zygote goes through mitosis and cytokinesis to create free-living diploid sporophyte

• diploid sporophyte goes through meiosis to create haploid spores

• haploid spores settle and regrow through mitosis and cytokinesis to form free-living haploid gametophytes (back to beginning)