Download The Smallest Units of Life

The Smallest Units of Life
Cells
What are Cells?
• Cells are the smallest unit that can carry out life
functions
• All cells have a cell membrane and cytoplasm
• The shape of a cell helps its function
ex. Red blood cells are circular
• They are prokaryotic (no nucleus) or
eukaryotic (nucleus)
• Cells can stand alone or work together in multi-cell
organisms
cells
tissues
organs
organ system
organism
What kinds of cells are there?
• Plant
have cell walls
have a definite shape
have no lysosomes
have chloroplasts
large central vacuole
• Animal
have no cell walls
can be any shape
have no chloroplasts
have lysosomes
small vacuoles
have a cytoskeleton
The Cell Theory
• With the invention of the microscope in the
1600’s people were able to explore the
world that they could not see
• They looked at blood, tartar, pond water,
plants and animals
• 3 men contributed to the cell theory:
Schleiden, Schwann and Virchow
Cell Theory Continued
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1.
2.
3.
Schleiden’s contribution was to state that all plants are
made up of cells
Schwann’s contribution was to state that all animals
are made up of cells
Virchow’s contribution was to state that all cells come
from other cells
Their ideas combined to create the cell theory:
All organisms are made up of one or more cells
The cell is the basic unit of all life
All cells come from other cells
Cell Processes-How cells move
things across the membrane
• The cell membrane determines what goes
in and out of the cell
• It is “selectively permeable”
this means that materials that can get through easily
will and those that are larger must get in on their
own
• Materials move in and out of cells in 3
ways:
Cell Processes-How cells move
things across the membrane cont.
1.
2.
3.
Osmosis-movement of
water from an area
where there is a lot to
where there is a little
Diffusion-movement of
molecules from where
there is a lot to where
there is a little
Active Transport-when
energy is required to
move material across
the membrane