CELLS
BASIC UNITS OF LIFE
___
INTRODUCTION
The structural and functional unit of life is a cell. They are also called the building blocks of life
or basic/smallest units of life that can replicate independently. By structural, it is meant that
they are arranged in an orderly manner and they combine together to make different structures
of the body. By functional it means that they are the smallest living being that can survive and
function on its own.
Classification of cells:
Cells are classified on the basis of the following:
1) Based on organelles: Prokaryotic or Eukaryotic
2) Mode of organistaion: uniclellular or multicellular
3) Shape and size
, 2
Prokaryotic cells Eukaryotic cells
Absence of membrane-bound organelles Presence of membrane-bound* organelles
Pro(before)= Primitive Membrane bound*= Enclosed by a
membrane separating their content from the
cytoplasm
Karyon=kernel (nucleus) Eu=True
Lack nucleus(which contains genetic info) Well-defined nucleus= contains chromatin
fibres (chromosomes)
Have nucleoid in direct contact with Complex structure:They tend to be larger and
cytoplasm. Nucleoid is their genetic material more structurally complex.
E.g. bacteria and archaea (performs all the Cellular Communication: Communicatw with
tasks by itself) eachother through complex signaling
pathways
Cell Structure
Name of the part Description Where found Function
Cell membrane Partially permeable Around the Controls what
membrane; forms a cytoplasm substances enter and
boundary around the leave the cell; doesn’t
cytoplasm-made up let content escape
of proteins and lipids
Cytoplasm Jelly like substance Enclosed by the cell 1. Contains the
enclosed with membrane subcellular structures
particles and or organelles
organelles in it 2. Site of chemical
reactions
Nucleus Circular or oval Found inside the Contains genetic
shaped; have a cytoplasm of a cell material; controlling
double-layered unit for every
membrane called organelle with the
nuclear membrane help of proteins;
covering it genes present in the
BASIC UNITS OF LIFE
___
INTRODUCTION
The structural and functional unit of life is a cell. They are also called the building blocks of life
or basic/smallest units of life that can replicate independently. By structural, it is meant that
they are arranged in an orderly manner and they combine together to make different structures
of the body. By functional it means that they are the smallest living being that can survive and
function on its own.
Classification of cells:
Cells are classified on the basis of the following:
1) Based on organelles: Prokaryotic or Eukaryotic
2) Mode of organistaion: uniclellular or multicellular
3) Shape and size
, 2
Prokaryotic cells Eukaryotic cells
Absence of membrane-bound organelles Presence of membrane-bound* organelles
Pro(before)= Primitive Membrane bound*= Enclosed by a
membrane separating their content from the
cytoplasm
Karyon=kernel (nucleus) Eu=True
Lack nucleus(which contains genetic info) Well-defined nucleus= contains chromatin
fibres (chromosomes)
Have nucleoid in direct contact with Complex structure:They tend to be larger and
cytoplasm. Nucleoid is their genetic material more structurally complex.
E.g. bacteria and archaea (performs all the Cellular Communication: Communicatw with
tasks by itself) eachother through complex signaling
pathways
Cell Structure
Name of the part Description Where found Function
Cell membrane Partially permeable Around the Controls what
membrane; forms a cytoplasm substances enter and
boundary around the leave the cell; doesn’t
cytoplasm-made up let content escape
of proteins and lipids
Cytoplasm Jelly like substance Enclosed by the cell 1. Contains the
enclosed with membrane subcellular structures
particles and or organelles
organelles in it 2. Site of chemical
reactions
Nucleus Circular or oval Found inside the Contains genetic
shaped; have a cytoplasm of a cell material; controlling
double-layered unit for every
membrane called organelle with the
nuclear membrane help of proteins;
covering it genes present in the
