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Title: AQA AS BIOLOGY PROKARYOTIC CELLS AND VIRUSES
Description: Detailed first year (AS) biology notes to aid key revision of topics and enhance knowledge.
Description: Detailed first year (AS) biology notes to aid key revision of topics and enhance knowledge.
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Prokaryotic Cells
Prokaryotic cells are smaller than eukaryotic cells
and have no nucleus or nuclear envelope
...
Eukaryotic Cells
Distinct nucleus with a nuclear
envelope
DNA is not associated with pro- DNA is associated with proteins
teins called histones
Some DNA may be in the form No plasmids and DNA is linear
of plasmids
No membrane-bound organelles
Membrane-bound organelles
Viruses
Viruses are acellular, non-living particles
...
No chloroplasts, only bacterial Chloroplasts present in plants
chlorophyll
and algae
They contain nucleic acids such as DNA or RNA as genetic material but can
only multiply inside living host cells
...
Cell wall made of murein
Where present, cell wall is
made of cellulose
May have a capsule
No capsule
Some viruses, like HIV are further surrounded by a lipid envelope
...
Bacteria:
All bacteria posses a cell wall: physical barrier that excludes certain substances /
protects against mechanical damage
...
Capsule: Protects bacterium from other cells
...
Plasmid: possesses genes that may aid the survival of bacteria in adverse conditions
Title: AQA AS BIOLOGY PROKARYOTIC CELLS AND VIRUSES
Description: Detailed first year (AS) biology notes to aid key revision of topics and enhance knowledge.
Description: Detailed first year (AS) biology notes to aid key revision of topics and enhance knowledge.