Cell Clasification and Structure
Prokaryotic cells are small and structurally simple
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Prokaryotic cells
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first appeared ~ 3.5 billion years ago
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"before nucleus"
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small, ~1/10th size of eukaryotic cells
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lack true, membrane-bound nucleus
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surrounded by plasma membrane
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lack true, membrane-bound organelles
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less complex than eukaryotic
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contain a simple DNA molecule
The eukaryotic cell probably originated as a community of prokaryotes
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fossil record indicates
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eukaryotes evolved from prokaryotes ~1.5 BYA
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how did eukaryoites arise?
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theory: through a combination of 2 processes
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membrane infolding
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endosymbiosis
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membrane infolding
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of plasma membrane of ancestral prokaryotic cells
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gave rise to endomembrane system of eukaryotic cells
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endosymbiosis
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thought to have generated first
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mitochondira
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heterotrophic prokaryote came to reside in ancestral prokaryote
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chloroplast
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photosynthetic prokaryote came to reside in ancestral prokaryote
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Cells can be classifited in prokaryotic and eukaryotic cells:
