CHAPTER 18

Endosymbiosis

The process where complex cells evolved from simpler prokaryotic ancestors, incorporating features such as mitochondria and chloroplasts.

Primary Endosymbiosis

The initial acquisition of mitochondria and chloroplasts by eukaryotic ancestors, involving no more than 1 or 2 membranes.

Secondary Endosymbiosis

The process where a eukaryotic cell engulfs another eukaryotic cell that already contains an endosymbiont.

Diplomonads

• A group of excavates

• two equal-sized nuclei

• anaerobic, parasitic lifestyle.

Parabasalids

• Excavates

• lack mitochondria and use hydrogenosomes to generate energy

• parasites.

Trypanosomes

• Parasitic excavates

• membrane flap for nutrient uptake

• trypanosome cell: characterized by their unique flagellum

Euglena (Euglenid)

• nonpathogenic excavate that is motile

• mixotroph: chemoorganotrophic and phototrophic lifestyles.

Ciliates

A major group of alveolates characterized by their use of cilia for motility and feeding.

Diatom frustules

Cell walls made of silica in unicellular, phototrophic eukaryotes.

Mycelia

A mass of hyphae that forms the vegetative structure of most fungi.

Chitin

The primary component of fungal cell walls.

Fruiting bodies

Reproductive structures such as mushrooms and puffballs that arise from fungi, facilitating spore dispersal.

Ascomycota genera

• Saccharomyces cerevisiae

Basidiomycota key genera

• Agaricus

• Amanita

Marine Red Algae in Archaeaplastida

• red because of phycoerthrin pigment

• oxygenic phototrophs adapted to marine environments.

Green Algae in Archaeplastida

• marine, freshwater, and terrestrial habitats

• oxygenic

chlorophytes that contain chlorophyll a abd b for photosynthesis

Geen algae in group Archaeplastida

AKA rhodophytes

red algae in Archaeplastida

Basidiomycota: Basidium

• mushrooms and puffballs, characterized by a spore-producing structure called basidium.

• haploid basidiospored formed by meiosis

• vegetative and sexual reproduction

Ascomycota characteristics

• sexual (mating) and asexual reproduction (conidia)

• spherical/oval

mycoses

infections caused by fungi

• athletes foot

• histoplasmosis

endosymbiosis characteristics

• membrane bound nucleus and other organelles

• 80s ribosome

• 70s for mitochondria and chloroplasts

eukaryotic phylogenetic tree

18 S rRNA

Giardia intestinalis

• Diplonomad, protozoan parasite

• cause giardiasis → diarrhea and gastrointestinal distress

• anaerobic

• uses mitosome

Trichomonas vaginalis

• parabasalid

• sexually transmitted parasite

Trypanosoma brucei

• cause africcan sleeping sickness

• Trypanosomes (excavates)