Chapter 25 Flashcards
Origin & Diversification of Eukaryotes
What are the 3 fundamental elements of Eukaryotes?
- Nucleus
- Organelles
- Structurally complex cytoskeleton
Protist
informal name for a diverse group of mostly unicellular eukaryotes
What does a structurally complex cytoskeleton allow a eukaryote to do?
- have asymmetrical form
- move, feed, grow
List the 3 stages of eukaryotes.(early records)
- initial diversification
- multicellular & appearance of novel features
- Rise of large eukaryotes
List the characteristics of initial diversification
- single celled
- all had a nucleus, flexible membrane, and cytoskeleton
- varied in size and shape
List the novel (new) features in the second stage
- complex multicellularity - organisms had differentiated cell types
- sexual life cycles
- photosynthesis
List the characteristics in that gave rise to large eukaryotes.
- body sized maximized
- increased taxonomic diversity
- increase types of morphological differences
- soft bodied
Endosymbiosis
symbiotic relationship where one organisms lives in the body or cell of another
Plastids
general term for chloroplasts and related organelles
Endosymbiont Theory
that mitochondria & plastids were formerly small bacteria that began living within larger cells.
Primary endosymbiosis
engulfment of a prokaryote by another living cell and incorporation of that prokaryote as on organelle
What stage of endosymbiosis is responsible for the initial eukaryotes mitochondria and chloroplast?
Primary endosymbiosis
Serial endosymbiosis hypothesis
suggesting that mitochondria evolved before plastids through a sequence of endosymbiotic events.
Secondary endosymbiosis
a eukaryotic cell engulfs a cell that has already undergone primary endosymbiosis.
How did secondary endosymbiosis occur?
when photosynthetic eukaryotic algal cells were ingested by heterotrophic eukaryotes.
Multicellularity in different eukaryotes arose ___.
independently
Multicellular colonies
complex of connected cells with little to no cellular differentiation
Complex mutlicellularity
complex of connected cells that are differentiated
Co-opting
changes in how existing genes are used rather than addition of new genes
List the 4 “Supergroups” of Eukaryotes
- Excavata
- SAR
- Archaeplastida
- Unikonta
List the 3 clades Excavata has
- Diplomonads
- Parabasalids
- Euglenozoans
List the characteristics of Dipolomonads
- Most in anaerobic environments
- Highly reduced mitochondria called mitosomes
- Many are parasites
Give an example of Dipolomonads
giardia intestinalis - lives in mammals intestines and is found in creek water
List the characteristics of Parabasalids
- most in anaerobic environments
- highly reduced mitochondria called hydrogenosomes
- many are animal symbionts or parasites
Give an example of parabasalids symbiont and parasite.
Its a gut mutualist in termites
human parasite called trichomonas vaginalis
List the characteristics of Euglenozoans
- highly diverse (hetetrophs, autotrophs, parasites)
- flagella with spiral or crystalline structure
What kind of “troph” is euglenozoans?
Mixotroph - meaning it can switch how it obtains energy