A view of the Cell
Discovery of cells
• Microscopes enabled biologists to see
cells and develop the cell theory.
• The cell theory states that the cell is the
basic unit of organization, all organisms are
made up of one or more cells, and all cells
come from preexisting cells.
• Using electron microscopes, scientists can
study cell structure in detail.
Cell Classification
• Cells are classified as prokaryotic or
eukaryotic.
Prokaryotic
• are molecules surrounded by
a membrane & cell wall.
They lack membrane
enclosed organelles.
kingdoms
• Monera (Eubacteria)
• Archaea
Eukaryotic
• have a nucleus and other
organelles and are enclosed
by a plasma membrane.
Some cells have a cell wall.
kingdoms:
• Protista
• Plantae
• Fungae
• Animalia
prokaryote
Eukaryotes
The plasma membrane
• Through selective permeability, the plasma
membrane controls what enters and leaves a
cell.
• The fluid mosaic model describes the plasma
membrane as a phospholipid bilayer with
embedded proteins.
Fluid Mosaic Model
Nucleus
• It contains most of the cell's genetic
material. It’s function is to maintain the
integrity of it’s genes and to control the
activities of the cell by regulating gene
expression.
• Cells make proteins on ribosomes that are
often attached to the highly folded
endoplasmic reticulum.
• Mitochondria break down sugar molecules
to release energy. Chloroplasts convert
light energy into chemical energy.
• The cytoskeleton helps maintain cell shape
and is involved in the movement of
organelles and materials.
The eukaryotic cytoskeleton. Actin filaments are shown in
red, microtubules in green, and the nuclei are in blue.