6/17/25 Flashcards

Messy Phylogeny

The phylogeny appears messy, but color schemes and lineage traces reveal phylogenetic signals.

Horizontal Transfer

Associated with endosymbiosis.

Mitochondria and Chloroplasts

Key endosymbiotic features.

Endosymbiosis

Multiple rounds involve primary, secondary, and sometimes tertiary stages.

Eight Major Lineages

Alveolates, Straminopiles, Rizarians, Excavates, Plants, Amoebozoans, Fungi, and Animals.

Multicellularity

A key innovation in eukaryotic diversity.

Choanoflagellate

The closest relative to all animals.

Alternation of Generations

Land plants alternate between sporophyte and gametophyte stages.

Alveoli

Air sacs under the cell membranes

Pseudopods

Extensions of the cytoplasm with cytoskeletal elements used to move and feed

Carotenoids

Photosynthetic pigments in chloroplasts

Mycelium

The main body of the fungus

Gametangia

Organs forming gametes that are protected

Synapomorphy

Plant embryo is protected

Waxy Cuticle

Prevent water loss

Closable Stomata

Regulate gas exchange and water loss

Globophytes

The earliest branching lineage after the first endosymbiotic event

Major Groups

There are three major groups with horizontal transfers between them.

Acquisition Order

Mitochondria were acquired first, followed by chloroplasts.

Chloroplast Formation

Photosynthetic bacteria were taken up to form chloroplasts.

Mitochondria Membranes

Eukaryotes with mitochondria typically have two membranes (inner and outer).

Pigment Variation

Different pigments mean different bacteria were taken up.

Primary Endosymbiosis

Primary endosymbiosis involves a non-photosynthetic eukaryotic cell engulfing a cyanobacterium.

Peptidoglycan Remnants

Peptidoglycan remnants suggest the evolutionary story.

Secondary Endosymbiosis Definition

Other photosynthetic eukaryotes, including some protists, have undergone secondary endosymbiosis.

Membrane Count

Usually, three membranes are seen, but sometimes four.

Flexible Cell Membrane

A flexible cell membrane allows the cell to move and engulf other cells.

Diversification Period

These diversified during the Precambrian period (1.5 billion to 600 million years ago).

Impact of Multicellularity

It allowed animals to become larger and more complex.

Artificial Selection Experiments

They used unicellular organisms and selected for traits that favor multicellularity.

Choanocytes Resemblance

Choanocytes, found in sponges, resemble choanoflagellates.

Dinoflagellates Abundance

Dinoflagellates are abundant and contribute to organic debris on the ocean floor.

Coral-Dinoflagellate Relation

Corals use dinoflagellates for carbohydrate production.

Straminopiles Flagella

They have two flagella, but some species have reduced or lost them.

Diatoms Silica Deposition

They deposit silica within structures resembling cell walls, creating different shapes.

Diatomaceous Earth Use

Diatomaceous earth contains diatom shells with sharp, jagged edges, used to prevent pest invasions.

Brown Algae Pigments

They have carotenoids, giving them a brownish color.

Foraminifera Limestone

They create sedimentary deposits that compress into limestone.

Radiolarians Endoskeleton

They secrete a glassy endoskeleton.

Cellular Slime Molds Vegetative State

In a vegetative state, they are single-celled with a haploid nucleus, reproducing through mitosis and fission.

Opisthokonts Flagella

If flagella are present, they are on the back (posterior) of the cell.

Limestone Production

Rizarians (specifically, Foraminifera) are responsible for much of the limestone production due to their calcium carbonate shells.

Saprobes Definition

Saprobes absorb nutrients from dead organic matter.

Hyphae Definition

Hyphae are tubular branches that extend immense distances underground.

Dry Rot Definition

Fungal infections can encroach within the xylem of plants, causing dry rot.

Chloroplasts as Synapomorphy

Chloroplasts are a synapomorphy (shared derived trait).

Waxy Cuticle Definition

Waxy cuticle to prevent water loss

Mycorrhizae Benefits

Beneficial associations with fungi (mycorrhizae) to promote nutrient uptake

Early Plant Lineages

The earlier lineages of plants were nonvascular and needed to live close to water sources.

Gamete and Spore Production

Gametes are produced by mitosis, and spores are produced by meiosis.

Early Land Plants

Early land plants (bryophytes) had a large gametophyte body.

Sporangium Function

The tip of the sporangium ruptures, releasing haploid spores into the environment.

Sporophyte Growth

Which means what follows fertilization is a sporophyte which grows out of the gametophyte.