Chapter 3: The basic unit of life
Unit 13: Cell components & functions Sipsang Sukphol (B.Sc. Biology, M.Ed)
13.1 COMPONENTS OF THE CELL
The major components of the cell are (1) cell membrane, (2) cytoplasm, and (3) nucleus.
13.1.1 Cell membrane (Plasma membrane)
Each cell has a limiting boundary, the cell membrane, plasma membrane or
plasmalemma. It is a living membrane, outermost in animal cells but next to cell
wall in plant cells.
It is flexible and can fold in (as in food vacuoles of Amoeba) or fold out (as in
the formation of pseudopodia of Amoeba)
The plasma membrane is made of proteins and lipids and several models were
proposed regarding the arrangement of proteins and lipids. The fluid mosaic model
proposed by Singer and Nicholson (1972) is widely accepted. It is represented in