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Cells and Cell
Structures
“Cell”
• Name means “small room”
• Basic structural, functional
and biological unit of all
KNOWN living organisms
• Smallest unit of life that can
replicate independently
Microscopes were used as early as the
1600s to look at things.
• 1665 Hooke used a
microscope to look at the
bark of a Cork-bark oak
• Saw this and named them
‘cells’
• Snowflake
Spurred more interest… better technology
• 1838: Schleiden concluded all plants are
made of cells
• 1839: Schwann stated all animals were made
of cells
• 1855: Virchow concluded new cells can only
be produced from existing cells
Cell Theory
• All living things are made of
cells
• Cells are the basic structural
and functional unit of living
things
• New cells are produced from
existing cells
Cell Theory
• What IS a theory?
• Why is it “Cell Theory” and not “Cell Law”?
• Do we know about “ALL living things”?
Prokaryotes and Eukaryotes
• Two (broad) categories of cells
• NO membrane-bound organelles = Prokaryotes
• HAS membrane-bound organelles = Eukaryote
Scanning electron
micrograph of human
brain neuron
www.scienceclarified.com
Scanning electron
micrograph of E. coli
in human intestine
www.listoid.com
Prokaryotes
• Smaller and ‘simpler’
• Bacteria are prokaryotes
• MOST living things are prokaryotes
Prokaryotes
Prokaryotes
• Smaller and ‘simpler’
• Bacteria are prokaryotes
• MOST living things are prokaryotes
• MOST of ‘you’ is prokaryotic
• YOU are outnumbered 10:1 in/on YOU!!!!
American Society for Microbiology, June 5, 2008
Scale between human cells
and bacterial cell
Eukaryotes
• Larger, more ‘complex’
• Eukaryotes have a nucleus
• MOST have other organelles
• Protists to animal/plant cells
Daphnia are NOT protists. They’re related
to lobsters- Crustaceans
Now…
• Start on Obj 6