Outline of the
structure, chemistry,
and functions of the
living cell.
Dr Sesay
Dr Saccoi
Outline
• Definition of a cell
• Theories on origin of the cell
• Timeline In development of the cell theory
• Classification of cells (taxonomy)
• Structure and function of parts the cell
- The cell wall (plants, bacteria and fungi)
- The cell membrane
- The organelles
Definition of a cell
• The cell is the basic structural and functional
unit of life
• It was first discovered by Robert Hooke in 1665
using a light microscope
Theories on origin of the cell
1. Spontaneous generation theory - this is an
outdated theory which stated that living
organisms could arise from nonliving matter as
a regular process in nature.
2. Biogenesis theory – This is the current
accepted theory, it states that living things
Disproving
Spontaneous
Generation
3. Abiogenesis theory – This theory agrees with
biogenesis theory but further explains that even
though living things can only come from living
things currently, the earliest living things to
ever exist had to have come from non-living
things (small organic molecules) when the
Cells can be classified into
two types:
Taxonomy/Classification
• Phylogenic classification uses cell DNA and
protein Amino acid sequence to further sub
classify these groups.
• Prokaryotic cells are divided into Archaea and
Bacteria by DNA and protein sequence
Cells can also be classified
by morphology in 5 kingdoms
Structure and function of
parts of the cell
Structures of Animal cell and
plant cell