BIOEE1780 Diversity 2

• Membrane enclosed nucleus
• Mitochondria (endosymbiosis of proteobacteria)
• Some have chloroplasts (endosymbiosis of cyanobacteria)
• Relatively large
• Generally multicellular such as protists
• Relatively complex

2 byA

• First step was the loss of the firm cell wall to form a flexible cell membrane.This allowed for larger cell size.
• To deal with increasing large cell size, infolding to increase surface area:volume ratio.
• Complex cell skeleton forms from microtubules and microfilaments.
• Internal membranes with ribosomes to synthesize proteins.
• The infolding cell membrane eventually enclosed the DNA, forming the nucleus
• Flagellum formed from microtubules, allowing the cell to propel itself.
• Endosymbiosis led to mitochondria and chloroplasts.

• They distribute daughter skeletons, allowing for mitosis to take place.
• In addition they allow for the development of flagellum.

• Primary endosymbiosis resulted from the incomplete phagocytosis of a bacterium.
• During endosymbiosis, rather than being ingested, the bacterium survived.
• When the host reproduced, subsequent generations would contain the descendants of the originally engulfed bacterium.
• The bacterial cells and the host cell developed a mutualistic symbiotic relationship: the host cell provided a safe environment and nutrients. The bacteria performed oxidative respiration, because it would’ve otherwise been poisoned by the increasing oxygen in the atmosphere at the time.

Aerobic proteobacterium.

Cyanobacterium.

• Synapomorphy of all plants.
• The common ancestor of glaucophytes, red algae, green algae, and land plants engulfed a cyanobacterium.
• All other occurrences of chloroplasts arose through secondary or tertiary endosymbiosis events.

A eukaryote, already carrying a symbiont, is engulfed by another eukaryote.

• Ancestor engulfed Green algae
• Euglenids (group of protists)

Common ancestor of stramenopiles and alveolates engulfed a red algae.

Dinoflagellates’ common ancestor engulfed a protist, which already had a chloroplast, because its ancestor had engulfed a red algae.

• Not a monophyletic group.
• Protists are eukarya that are not animals, plants or fungi.
• Have diverse characteristics.

• Unicellular
• Sacs called alveoli under the cell membrane to give it structure and support.
• Are photosynthetic and have chloroplasts that have been acquired through the secondary endosymbiosis of red algae.
• Dinoflagellates
• Ciliates
• plasmodium

• 2 flagella in an equatorial groove and longitudinal.
• Tertiary endosymbiosis of protist.
• A few are freshwater, many are abundant as marine plankton.
• Alveolites
• Endosymbionts of coral (corals are a result of quaternary endosymbiosis)
• Responsible for red tide blooms and bioluminescence (triggered by movement as an anti-predator defense mechanism).

Dinoflagellates release a neurotoxin in high temperatures, which leads the corals to expel them.

• paramecium,
• characterized by short, numerous flagella.
• Aquatic.
• Can be multinuclear.
• alveolites

• Intracellular parasites with vestigial chloroplasts.
• Alveolites.
• Complex of proteins at the apical prominence attach to and penetrate the host cell.

• Two flagella that are not of equal length. One the flagella is covered in tubular hairs.
• Many however, have lost their flagella.
• Brown algae
• diatoms

• Large multicellular algae
• Kelp forests, support a number of organisms such as sea otters, echinoderm sea urchins and sea lions.
• Stramenopiles
• Secondary endosymbiosis of red algae.

• Unicellular
• Stramenopiles
• Secondary lost their double flagella
• Secondary endosymbiosis of red algae.
• Deposit silica in their cell membranes and thus have beautiful shells.
• Major component of plankton and almost all are marine.
• 20% of carbon fixation on earth.

• Reduced or lost mitochondria
• Euglenids
• Giardia
• Trypanosoma

• Unicellular parasite
• Intestinal parasite
• Water borne
• Excavate
• Degenerate mitochondria and obtain energy from their host,

• Excavates
• Have mitochondria, one large flagellum
• Secondary endosymbiosis of green algae.
• Excavates

• Single celled, single enlarged mitochondria
• Some are free living while others are parasites
• Excavates
• Some cause debilitating sickness, such as sleeping sickness, Chagas’ disease, Leishmaniasis.

• Lobe shaped pseudopods (lobe shaped extension pods) used for movement
• Move by cytoplasmic streaming (slime molds)
• Amoeba
• Slime molds (unicellular, but multinucleate)

• Loss of the rigid cell wall and development of a flexible cell membrane.
• This led to larger size, the potential for infolding and compartmentalization, and endocytosis.

• Mitochondria is double membrane bound (its own membrane and the membrane that enclosed it.
• Mitochondria has its own DNA
• Mitochondria has its own circular chromosome. (like a proteobacterium)

• Chloroplast is double membrane bound.
• cpDNA is within chloroplast.
• Own circular chromosome.

• The number of membranes around the chloroplast indicates the events of endosymbiosis.
• Glaucophytes, red algae, green algae and lands plants have a double membraned chloroplast.
• Dinoflagellates have 4 membraned chloroplasts.

• Has a chloroplast from primary endosymbiosis.
• Retain a small amount of peptidoglycan in chloroplast membrane.

euglenoids

stramenopiles

dinoflagellates

ameobozoans

dinoflagellates

brown algae

excavates

trypanosoma

yes

nope none