Biology 1002B Lecture Notes - Lecture 12: Rubisco, Nuclear Dna, Endoplasmic Reticulum
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Evolution of Eukaryotes (2.5b, 2.5c)
Formation of Endomembrane System
o Ancient prokaryotic cell
o Through gradual in-folding of
plasma membrane
o Endomembrane system formed
Golgi apparatus
Endoplasmic reticulum
Nuclear envelope
Energy-Transducing Organelles
o Endosymbiosis
Prokaryotic ancestors of
mitochondria and
chloroplasts were engulfed
by larger prokaryotic cells
Formed mutually
advantageous relationship – symbiosis
Mitochondria came first - capable of using oxygen for aerobic respiration
Chloroplasts developed from ingested cyanobacteria
No evidence as to whether endomembrane system came first or endosymbiosis
o Theory Evidence
Morphology
Form or shape of both organelles is similar to prokaryotic cells
Reproduction
Mitochondria or chloroplasts are derived only from preexisting mitochondria and
chloroplasts – divide by binary fission like prokaryotic cells
Genomes (Genetic Information)
Both organelles contain their own DNA – codes for the proteins essential for the
organelles function
Transcription & Translation
Contain a complete transcription and translational machinery – enzymes and
ribosomes
Similar ribosomes to prokaryotic cells
Electron Transport chain
Can generate energy in the form of ATP through their own ETC
Driving Evolution of Eukaryotes
Earliest cells were prokaryotic and anaerobic
2.2 billion years ago cyanobacteria evolve
o Oxygenic photosynthesis (photosynthesis produces O2)
o Atmosphere contains oxygen
Oxygen perfect as terminal electron acceptor
o Prokaryotes that undergo aerobic respiration are evolved
Oxygenic Phosphorylation
o More ATP can be produced through cellular respiration
Eukaryotic Cells Are Bigger & More Complex
Endosymbiosis cells overcame energy barrier
Prokaryotic cells made enormous amounts of ATP through mitochondrion