Prokaryotic V Eukaryotic
• Prokaryotic cells –
(‘pro’ = before, ‘karyote’ = nucleus) have no
nucleus or nuclear membranes.
• Eukaryotic cells –
(‘eu’ = true, ‘karyote’ = nucleus) have a
nucleus bounded by nuclear membranes.
Timeline showing evolution
of prokaryotes and
eukaryotes
Structure of a generalised bacterial cell
Nucleoid – general area
where DNA lies
Plasmid –small circular
piece of DNA
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diagram
Comparisons....
Prokaryotic cells
• No true nucleus, only diffuse area(s) of
nucleoplasm
• No nucleolus
• Circular strands of DNA but no proteins
to make up chromosomes
• No membrane bound organelles
• No chloroplasts, only photosynthetic
lamellae in some bacteria
• Ribosomes are smaller (70S)
• Flagella if present lack internal 9+2
microtubule arrangement
• No ER or associated Golgi apparatus and
lysosomes
• Cell wall made of peptidoglycan
Eukaryotic cells
• Distinct nucleus, with nuclear
envelope
• Nucleolus is present
• Chromosomes present in which DNA
is located, DNA molecules linear
• Membrane bound organelles are
present
• Chloroplasts present in plants and
algae
• Ribosomes are larger (80S)
• Undulipodia have 9+2 internal
microtubule arrangement
• ER present along with Golgi apparatus
and lysosomes
• Where present, cell wall is made
mostly of cellulose or chitin.
Evolution of
Eukaryotic
Organelles
Lynn Margulis
Prokaryotes and disease
MRSA (methicillin-resistant
Staphylococcus aureus)
Resistance coded on plasmid DNA – bacteria can share
plasmids with each other – pass on resistance to
daughter cells during binary fission
Prokaryotes that help
Food industry
Mammalian intestines
Skin
Sewage treatment