Lecture 3- Eukaryotes Flashcards
True or False: Primary phagocytosis of a cyanobacterium led to the ancestor of today’s mitochondria
False; the primary phagocytosis of a cyanobacterium led to the ancestor of red and green algae
What is a mixotroph?
Organism capable of autotrophy (photosynthesis) and heterotrophy
________ is the process in which a eukaryote engulfs a living prokaryote like bacteria
Primary endosymbiosis
What are plastids?
Membrane-bound organelles, like chloroplasts, that result from secondary endosymbiosis
What is the pigment responsible for the color of red algae?
Phycoerythrin
________ occurs when a eukaryote engulfs another eukaryote
Secondary endosymbiosis
What shared derived trait(s) do all stramenopiles share?
Two flagella (one short/smooth and one long with hair-like projections)
True or False: Possessing a mitochondria is a homologous characteristic for the eukarya
TRUE
What shared derived trait(s) do all archaeplastida share?
Chloroplasts via primary endosymbiosis
True or False: The eukaryotic tree is a polytomy
TRUE
An organism is observed to have a protective shell made of calcium or silica. To which eukaryotic supergroup could this organism belong?
SAR
Which eukaryotic supergroup is sister to the opisthokonta?
Amoebozoa
What shared derived trait(s) do all alveolates share?
Alveoli
In which eukaryotic supergroup are red and green algae found?
Archaeplastida
What shared derived trait(s) do all opisthokonta share?
Genetic similarities
What is the function of alveoli in alveolates?
Support plasma membrane
True or False: Nucleariids are sister to fungi and choanoflagellates are sister to animals
TRUE
Eukaryotic Cell Structure- List key derived traits
- Nucleus
- Membrane-bound organelles
- Well developed cytoskeleton: Network of fibers within cell- support, allows for asymmetry, changing shape
Endosymbiosis
Relationship between 2 species in which 1 lives inside the other, common in evolutionary history (mitochondria, chloroplasts)
Serial Endosymbiosis
Series of endosymbiotic events
Primary Endosymbiosis
Phagocytosis of bacterium by larger cell
Describe the first primary endosymbiosis
Mitochondria (first): Alpha proteobacteria (aerobic) within archaea (anaerobic)
Describe later primary endosymbiosis
Chloroplasts (later): Cyanobacteria within heterotrophic eukaryote
Secondary Endosymbiosis
Bigger eukaryote (heterotrophic) engulfs smaller eukaryote (autotrophic) -> secondary plastids
Plastid
General term for chloroplasts and related organelles
Chloroplasts were derived from cyanobacteria via ___________ endosymbiosis
Primary
Secondary plastids were derived from red or green algae (eukaryotes) via ______________ endosymbiosis
Secondary
Heterotrophic eukaryote with mitochondria engulfs cyanobacteria ->
Primary endosymbiosis, leads to green algae (autotrophic eukaryote with chloroplasts)
Heterotrophic eukaryote engulfs green algae ->
Secondary endosymbiosis, leads to autotrophic eukaryote with secondary plastids
Is eukaryotic evolution rapidly changing hypotheses?
Yes
5 Eukaryotic Supergroups
Archaeplastida, SAR, Amoebozoa, Opisthokonta, Discoba
What is included in the 5 eukaryotic supergroups?
Protists, plants, fungi, animals
Protists (General)
“The very first”
Represents the 1st eukaryotic cells, does not include plants, animals, and fungi
Mostly unicellular, complex cellular organization
Nutritional Strategies of Protists
Photoautotrophs, heterotrophs, mixotrophs
Mixotrophs
Capable of photosynthesis and heterotrophy
Ancestral Eukaryotic Traits
- Nucleus, membrane-bound organelles
- Aerobic respiration
- Mitochondria from primary endosymbiosis
What is the shared derived trait of archaeplastida?
Chloroplasts via primary endosymbiosis
- Ancestral archaeplastids participated participated in secondary endosymbiosis
ARCHAEPLASTIDA (what is included)
Red algae, green algae (chlorophytes, charophytes), land plants (ALL PHOTOSYNTHETIC)
Red Algae
ARCHAEPLASTIDA
- Primarily multicellular, often highly branched
- Red due to phycoerythrin
- Absorb blue, green light
- Many live very deep
- Usually warm, tropical water
Green Algae (Chlorophytes and Charophytes)
ARCHAEPLASTIDA
- Closely related to land plants- very similar chloroplasts
- Many forms- unicellular, colonial
2 main groups
Chlorophytes- mostly freshwater
Charophytes- clade that contains plants
SAR
Grouped based on genetic evidence
Shared derived trait: Secondary endosymbiosis of red algae
Includes 3 major clades: Stramenopiles, Alveolates, Rhizarians
Stramenopiles
SAR
Shared derived traits: Often have flagellum with hair-like projections
Often paired with “smooth” flagellum
3 main groups: (all photosynthetic)
- Diatoms
- Golden algae (TINY)
- Brown algae- multicellular
Alveolates
SAR
Shared derived trait: Alveoli: Flattened vesicles just inside plasma membrane- support membrane
Several large and important groups:
- Dinoflagellates
- Apicomplexans
- Ciliates
Rhizarians
SAR
Shared derived trait: Genetic similarities
Often have protective shells of calcium or silica
Radiolarians
Foraminiferans
Cercozoans
Important geologically
Amoebozoans
Typical “blob” shape
Lobe- or tube- shaped pseudopodia
Slime molds- not fungi
Entamoebas- free-living or parasitic
Opisthokonta
Diverse group
Includes animals, fungi, several groups of protists
Nucleariids- protists, closely related to fungi
Choanoflagellates- unicellular, closely related to animals
Discoba
Extremely diverse
Shared derived traits: Crystalline rod in flagella
Some have secondary plastids via green algae- mixotrophic
Trypanosomes and Euglenids
