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Cells
Cell Discovery
1665
• Robert Hooke: Around the time of Newton
– discovered the cell
– Saw dead cells of a cork plant
– Called them cells because they related to his
‘cell’
Cell Discovery
1673
• Antony van Leeuwenhoek
– Saw first live cell
Cell Theory
150 Years Later
1. All living things are composed of one or
more cells
2. Cells are the basic units of structure and
function in an organism
3. Cells come only from the reproduction of
existing cells
Cell Diversity
• 200 different types of cells in our body
• Most are microscopic
• Few can be seen without a microscope
– Frog egg cells
– Giraffe nerve cell in leg (2 meters long)
Cell Shapes
• Why are cells shaped differently?
Shape Determines Function!!
Cell Shapes
• What does a nerve cell
look like?
• How does a skin cell
appear?
Cell Shapes
• What about a white blood cell?
• Why??
Shape Determines Function!!
Internal Organization
• Cells have structures called organelles
– Perform specific functions in the cell
– Like miniature organs
Why are Cells so Small?
• Surface area to volume ratio!!
– As a cell gets larger, it adds volume faster than
it adds surface area
– (In English) The bigger the inside, the less area
there is on the outside for stuff to pass through
• Modeling Activity
Animal Cell Organelles
Taken from www.cellsalive.com
• Nucleus: Brain
– Control center of the cell
– Surrounded by 2 membranes
– DNA found here
Animal Cell Organelles
Endoplasmic Reticulum (ER): Smooth & Rough
• Rough ER
– Contains ribosomes
– Synthesizes proteins
• Smooth ER
– Lacks Ribosomes
– Synthesizes fats
Animal Cell Organelles
• Golgi Apparatus (golgi body): UPS Center
– Packages and transports moleules
Animal Cell Organelles
• Lysosomes: Police force & Recycle Center
– Digest invaders (such as bacteria)
– Recycle materials from old organelles
Animal Cell Organelles
• Mitochondrion: Power house
– Provide the cell with energy
– ATP important here
– Surrounded by 2 membranes
Animal Cell Organelles
• Cytosol: Soup of the cell
– “Bathes” other organelles with nutrients
• Cell membrane: Gatekeeper
– Controls what goes in or out of the cell
Plant Cell Organelles
• Vacuole: Landfill & Scaffolding
– Stores water, chemicals, and wastes
– Important in plant rigidity
Plant Cell Organelles
• Chloroplasts: Photosynthesis factories
– Photosynthesis occurs here
– Gives plants their green color
– Surrounded by 2 membranes
Plant Cell Organelles
• Cell wall: Shape & Protection
– Provides plants with their shape (no bones)
– Protects the plant (no skin)
Prokaryote Cell Organelles
• Single Cell
• Cell wall
• No nucleus
– Nuclear region
• No membrane
bound organelles