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.