Download aerobic respiration

Marek Mentel
Prednáška, Gymnázium GJH, marec 2012
Are eukaryotes all about oxygen?
...and what Earth history has to do with it?
Marek Mentel
Prednáška, Gymnázium GJH, marec 2012
Lecture content
• What are eukaryotes - eukaryotes specific features
• Eukaryotes origin theories
• Mitochondria types i.e. aerobic and anaerobic mitochondria
hydrogenosomes
mitosomes (cryptons)
• Energetic metabolism of individual mitochondria forms i.e. respiration
aerobic
anaerobic
fermentation
chemolithotrophy
• Mitochondria origin in the context of Earth geochemistry changes
Cytology - Prokaryotic & Eukaryotic cells comparison
Cytology - Eukaryotic cells specific features
Nucleus / EndoMembrane system / Golgi apparatus
Cytoskeleton / Flagella & Cilia
Endocytosis e.g. Phagocytosis
Mitosis
Sex – Meiosis & Fertilization
Mitochondria
Plastids
Peroxisome
Linear chromosomes (centromere, telomere, telomerase)
Spliceosome (spliceosomal Introns splicing - mRNA export coupling)
Habitats and Energetics - Prokaryotic & Eukaryotic
cells versatility comparison
aerobic respiration
anaerobic respiration
!! not true for eukaryotes !!
Eukaryotic cells origin theories review
Phagocytosis first / Mitochondria late view Mitochondria first / Phagocytosis late
view
Eukaryotic cells origin theories - prokaryotes within
prokaryotes plausibility
Mealybug Planococcus citri
endosymbiotic γ-proteobacteria
within ß-proteobacteria
Eukaryotic cells origin theories - ox-tox hypothesis
Eukaryotic cells origin theories - hydrogen hypothesis
Aerobic mitochondria
•
Biosynthetic pathways:
Heme synthesis
Fe-S synthesis
Ubiquinone synthesis
•
Metabolism:
Amino acids
Carbohydrates
Nucleotide
&
Lipid
•
Energetics:
Krebs cycle
aerobic respiration – oxidative phosphorylation
aerobic respiration
(facultative) Anaerobic mitochondria
• Unicellular protists & Metazoa:
Ciliates
nitrate, nitrite
Fungi
nitrate, nitrite, sulfur
Nematodes
fumarate
Plathelminths
fumarate
Snails
fumarate
Bivalves
fumarate
anaerobic respiration
Chemolithotrophic mitochondria
• Metazoa:
Bivalves
Polychaete worm
Crustaceans
chemolithotrophy – inorganic electron donor (S2-, HS-, H2S)
Hydrogenosomes and Mitosomes (Crypton) - MLOs
no energy metabolism
Mitosome
fermentation
– substrate-level phosphorylation
Hydrogenosome
• Unicellular anaerobes:
Parabasalids
(Trichomonas)
Ciliates
(Nyctotherus)
Chytridiomycete fungi
(Neocallimastix)
Amoeboflagellate
(Psalteriomonas)
Stramenopile
(Blastocystis)
Diplomonads
(Giardia)
Entamoebids
(Entamoeba)
Microsporidia
(Encephalitozoon)
Apicomplexan
(Cryptosporidium)
 Mitochondria, Hydrogenosomes, Mitosomes common features:
double membrane
protein targeting / import
iron-sulfur clusters synthesis
mitochondrial carrier family proteins
Hydrogenosomes and Mitosomes structure
hydrogenosome with cristae - N.ovalis
mitosome - Giardia
& Methanogen
mitochondria
& EReticulum
hydrogenosome without cristae
Neocallimastix patriciarum
mitosome - Cryptosporidium
(facultative) Anaerobic mitochondria – Fasciola hepatica
Anaerobic mitochondria / Hydrogenosome – Nyctotherus ovalis
Hydrogenosome – Piromyces sp. E2
Mitosome – Giardia intestinalis
Earth history - Geological TimeScales
eukaryotes origin
P - Pleistocene
Holocene
Geochemical history of Earth – atmosphere
oxygenation
eukaryotes origin
Earth history – significant lag in oceans oxygenation
& Canfield oceans chemistry
slight atmosphere oxygenation
continents weathering
sulfate-reducing bacteria radiation
Geochemical history of Earth – significant lag in
oceans oxygenation & Canfield oceans
eukaryotes origin
Anbar & Knoll, 2002
Earth history – significant lag in oceans oxygenation
& Canfield oceans
eukaryotes origin
Eukaryotic anaerobes & Proterozoic ocean chemistry
Dietrich, 2006
Mentel & Martin, 2008
Origins of mitochondria, hydrogenosomes and
mitosomes
Glycolysis - backbone of energy metabolism in Eukaryotes
Martin, 2001
Metabolically flexible mitochondria – Arenicola marina
Take home messages:
• Eukaryotes and Mitochondria
• Mitochondria:
O2
aerobic
oxidative phosphorylation
anaerobic
chemolithotrophic
hydrogenosomes – not uniform
mitosomes
• genome
• cristae
substrate-level
phosphorylation
no energy metabolism
• Anaerobic mitochondria & eukaryotic anaerobes make sense in
light of Proterozoic ocean chemistry
Obligate aerobes like ourselves seems to represent specialized
adaptation to recently oxygenated habitats
Take home messages:
• geochemical Earth history (changing Earth)
&
interconnection
Eukaryotes evolution
?
what makes mitochondria an essential compartment for eukaryotic cell –
where is the limit for its reduction
• not energy metabolism
- mitosomes
- cryptic mitochondria (Cryptosporidium parvum)
- mitosomes (Giardia intestinalis (syn. lamblia))
 iron-sulfur cluster biosynthesis
- cryptic mitochondria (Cryptosporidium parvum)
- mitochondria (yeast)