Cells
Cell Theory
 All living organisms are composed of cells.
 They may be unicellular or multicellular.
 The cell is the basic unit of life.
 Cells arise from pre-existing cells.
Modern Cell Theory
1. all known living things are made up of a cell or cells.
2. the cell is structural & functional unit of all living things.
3. cells come from pre-existing cells by division.
4. Most cells contains hereditary information which is
passed from cell to cell during cell division.
5. All cells are basically the same in chemical composition.
6. all energy flow (metabolism & biochemistry) of life
occurs within cells.
Two Basic Types of Cells
 Prokaryotic (Bacterial cells)
 Eukaryotic (EVERYTHING else!!)
Prokaryotic Cells
 Bacteria
 Simple
 Usually 1 chromosome
 May have Plasmid
(Circular, double
stranded DNA)
 No membrane-bound
organelles
 DNA  Nucleoid region
 Have ribosomes
E. coli - Gram-negative,
strains undergoing
conjugation. E. coli can cause
urinary tract infections,
traveler's diarrhea and
nosocomial infections.
Bacteria
E.coli at 1000x
(Our scope)
E. coli At 10 000X (a little
better)
Although Not Living, Here are Viruses
(Bacteriophages) Attacking a Bacterium
Eukaryotic
 Membrane-bound organelles
 Mitochondria Cellular Respiration takes place to produce
energy (ATP molecule)
 May be autotrophic (undergo photosynthesis that requires
light or chemosynthesis that does not use sunlight but uses
other “chemicals” such as CO2 or methane
 May be heterotrophic (consumes their food)
 True nucleus
 Plants have cell wall
 Many are multi-cellular; some are single-celled
 Genes on chromosomes, some of which code for proteins
 And no Algae are NOT plants……they are protists!
“Typical” Plant Cell
“Typical” Animal Cell Micrograph
“Typical “ Animal Cell
Cells are Specialized  A Few
Examples
 Red blood cells are in
abundance and carry
oxygen (O2) to your
cells
 White blood cells fight
infection
 Nerve cells send
impulses (electric and
chemical signals)
 Sperm cells  Male
gametes that carry
genetic information
 Ovum  Female
gamete that carries
genetic information
Eukaryotic Cells - Plant
Mitochondria
Cell/Plasma
Membrane
Cell Wall
Nucleus
Nucleolus
Chloroplast
Central
Vacuole
Eukaryotic
 Includes everything
EXCEPT
bacteria……even this
guy (yes, he’s real!)
 the hydrothermal
worm lives around
thermal vents at the
bottom of the
ocean……really tiny
(568/1000 of a
millimeter)
More Tiny Critters!
 A dust mite about half a
million times
amplification…….these dudes
live in your mattress,
pillow…….
The house dust mite, D. pteronyssinus