Single Cell Eukaryotes Flashcards
Three domains of life
Bacteria
Archaea
Eukaryotes
Endosymbiosis theory:
1) phagocytosis of bacterial cell (red cyanobacterium)
2) phagocytosis causes double membrane mitochondria (one cellular, one bacterial)
3) eukaryote also takes up plastids
4) mitochondria also engulfs plastids leaving them with own set of DNA (Always inherited from the mother)
Evidence for Endosymbiosis theory (4)
- mito and plastids have own genome
- similar plastids found in divers lineages of protists
- molecular and structural similarities between mitochondria and plastids
- genomic sequences of mitochondria show similarity with that of some prokaryotes
Similarity of Mitochondria and Bacteria
1) size/morphology
2) mitochondrial division similar to bacterial binary fission
3) circular DNA
4) protein synthesis machinery (rRNA/tRNA)
5) phylogenetic analyses and signature sequences
Types of unicellular eukaryotes (2)
1) Autotrophic
2) Heterotrophic
Autotroph
Produce their own energy (Ex, Chloroplast)
Heterotroph
Food is sourced from organic compounds
Groups (clades) classified by (5)
Molecular sequence Cell ultrastructure Presence/absence of locomotory structures Presence/absence of mito and plastids Structure of membrane
Clades (5)
1) Flagellates
2) Ciliates, apicomplexa, etc
3) Amoebae
4) Algae
5) Opisthokonts
Flagellate subgroups (3)
Diplomonadida (giardia)
Parabasalida (Trichomonas)
Euglenozoa (Trypanosoma)
Ciliate/Apicomplexa Subgroups
Apicomplexa (babesia)
Ciliata (Balantidium coli - pigs)
Flagellates
flagellated
anterior (front) flagella
2 or more flagella per cell
highly modified mitochondria
Diplomonadida
Subgroup of Flagellates lack mitochondria possess Mitosomes instead - ATP gen. most are Anaerobic most are Symbiotic
Giardia
Diplomonadida
Intestinal parasite of humans, wild/domestic animals
Resistant cysts contaminate water
Diarrhoea in cats, dogs, caged birds
Parabasalida
Subgroup of Flagellates lack mitochondria Posses Hydrogenosomes Most are anaerobic ALWAYS Symbiotic
Trichomonas
STD in humans and cattle
Relies on direct transmission
Severe disease, especially in female repro.
Males usually asymptomatic
Humans - T. Vaginalis (increase HIV risk)
Cattle - T. Foetus (abortions risk)
Euglenozoa
Subgroup of Flagellates
Many autotrophic and photosynthetic
Contain mitochondria
Kinetoplastids
Part of Euglenozoa –> part of flagellates
Flagellar movement
Free living and parasitic
Asexual reproduction by binary fission
Trypanosoma
Kinetoplastid –> Euglenozoa –> Flagellate
live in circulatory system of vertebrates
Humans: Sleeping sickness, chagas disease
Animals: Nagana
Intermediate host for Trypanosoma (2)
Old world: Tsetse Fly
New world: Reduviid bugs (kissing bugs)
Apicomplexa
4000 species obligate parasites INTRAcellular parasites Apicomplexa used for cell invasion move by small movements of cytoskeleton
Example of Apicomplexa parasites
Babesia causes babesiosis in cattle
intermediate host: cattle tick
Ciliates
Dual nucleus
Freshwater unicellular alveolates
cilia for movement and feeding
Ciliates of veterinary importance (1)
Balantidium coli (pigs)
Conjunction
type of asexual reproduction micronuclear replication (1 to 4), 3 die mitosis then occurs (up to 4 again) nuclei swap nuclei fuse macronuclei form
Rumen Ciliates
Essential for digestion
500,000 ciliates per mL, 100L per rumen = 50x10^9
Amoebae
Cells that move by cytoplasmic flow Flagellum USUALLY absent heterotroph soil, fresh, marine environments movement: Pseudopodia (false feet) Predator
Opportunistic Amoebae (2)
Acanthamoeba
naegleria
can enter brain/eye through freshwater contact
Entamoeba Histolytica
causes dysentery
also found in guts of dog by non-pathogenic
Red Alga
(rhodophyta)
some multicullular
use chlorophyll and other pigments (makes them RED)
Green Algae
Use chlorophyll (Green) freshwater, marine, soil unicellular, colonial, multicellular forms autotrophs in marine CLOSEST RELATIVE TO PLANTS
Opisthokonts
- Posterior flagellum
- unicellular/multicellular both have single flagella
Example) Sperm
Choanoflagellates
- “choano’ –> Collar
- Flagella produce water current for feeding
- many unicellular, some colonial
- CLOSE RELATIVE OF ANIMALS
Animals are more closely related to _______ than they are to other protists
Opisthokonts
Animals arose from?
Choanoflagellate ancestors
4 types of Interspecific interactions
1) Amensalism (-/0)
2) Commensalism (+/0)
3) Mutualism (+/+)
4) Parasitism (+/-)
Mutualism
(+/+): Both species benefit
Ex)
- Ants and thorny acacia
- Ciliates digest cellulose in ruminant stomach
- Bacterial produce Vit. K in human colon
Commensalism
(+/0): One benefits and one is unaffected
Ex) Adult cow stomach flukes
Pigs and the ciliate Balantidium coli
Malaria
Apicomplexan Plasmodium falciparum Mosquito is host Liver infected 1st; Blood infected 2nd Blood parasite - haemolysis/fever/blood becomes sticky
Coccidiosis
Apicomplexam
Gastrointestinal parasite
Transfer through cyst ingestion
Important parasite in livestock + wildlife conservation and rehabilitation
Life cycle of Coccidiosis
1) Oocyst with sporozoites infect intestinal mucosa
2) Development into trophozoites in intestinal cells
3) Trophozoites infect sex cells
4) Trophs undergo binary fizzion in MALE sex cells and fertilize and infected egg which is infected, but hasnt undergone binary fission.
5) Fertilization occurs and ovum is released
6) Cyst released in faeces where troph divides into 2 within 1 ovum
African Trypanosomiasis
Flagellate Transmission: Effected Tsetse fly Affects humans and domesticated animals Humans: Sleeping sickness Cattle: Nagana
Gene duplication
Primary source of producing new genes \
Homologs
traits from a common ancestor
Orthologs
Traits in different species but derived from a common ancestor
Paralogs
Similar trait but with a different function and do not share a common ancestor
First line of defence in the immune system?
Interferon-alpha
IFN-alpha
Relationship between RNA placticity and genome size
Increased RNA plasticity equals a reduced genomic diversity/evolution
Octopus
Have many editing site in RNA (RNA plasticity)
RNA changes instead of DNA
