Cells

Cell Discovery1665

• 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 Discovery1673

• Antony van Leeuwenhoek– Saw first live cell

Cell Theory150 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 OrganellesTaken from www.cellsalive.com

• Nucleus: Brain– Control center of the cell– Surrounded by 2 membranes– DNA found here

Animal Cell Organelles

• Smooth ER– Lacks Ribosomes

– Synthesizes fats

• Rough ER– Contains ribosomes

– Synthesizes proteins

Endoplasmic Reticulum (ER): Smooth & Rough

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