Study Notes
The Cell
It is the basic unit of life. All living things are made
up of cells.
A cell is composed primarily of four elements—
carbon, hydrogen, oxygen and nitrogen and trace
elements.
Living things are composed over 60% water.
The major building substance of cell is protein.
Cells vary in size from microscopic to over a meter
length. Shape of the cells often reflects function.
,NUCLEUS
Governs the activities of the cell and is necessary
for reproduction. It contains genetic material called
deoxyribonucleic acid (DNA), which carries
hereditary instructions and directs the production
of proteins.
Characteristics structures:
Nuclear envelope is a two- membrane boundary
between the inside of the nucleus and that of
the cytoplasm.
Nucleoplasm is the fluid portion of the nucleus
Chromosomes are substances containing DNA,
the cell’s hereditary materials and package DNA
and control gene expression.
Nucleolus is a dense cluster of DNA and materials
used to assemble the sub units of ribosomes.
, PLASMA MEMBRANE
Limits and encloses the cytoplasm and acts as a
selective barrier to the movement of substances
into and out of the cell.
Composed of a bilipid layer containing proteins.
Proteins act a enzymes or carriers in membrane
transport, form pores ,provide reception sites for
hormones and other chemicals or play a role in
cellular replication and interactions during
development and immune reactions.
CYTOPLASM
Where most cellular activities occur. Its fluid
substance called cytosol contains e inclusions,
stored or inactive such as fat globules, water
vacuoles, crystals in the cytoplasm and specialized
bodies known as organelles.
The specialized organelles are:
The Cell
It is the basic unit of life. All living things are made
up of cells.
A cell is composed primarily of four elements—
carbon, hydrogen, oxygen and nitrogen and trace
elements.
Living things are composed over 60% water.
The major building substance of cell is protein.
Cells vary in size from microscopic to over a meter
length. Shape of the cells often reflects function.
,NUCLEUS
Governs the activities of the cell and is necessary
for reproduction. It contains genetic material called
deoxyribonucleic acid (DNA), which carries
hereditary instructions and directs the production
of proteins.
Characteristics structures:
Nuclear envelope is a two- membrane boundary
between the inside of the nucleus and that of
the cytoplasm.
Nucleoplasm is the fluid portion of the nucleus
Chromosomes are substances containing DNA,
the cell’s hereditary materials and package DNA
and control gene expression.
Nucleolus is a dense cluster of DNA and materials
used to assemble the sub units of ribosomes.
, PLASMA MEMBRANE
Limits and encloses the cytoplasm and acts as a
selective barrier to the movement of substances
into and out of the cell.
Composed of a bilipid layer containing proteins.
Proteins act a enzymes or carriers in membrane
transport, form pores ,provide reception sites for
hormones and other chemicals or play a role in
cellular replication and interactions during
development and immune reactions.
CYTOPLASM
Where most cellular activities occur. Its fluid
substance called cytosol contains e inclusions,
stored or inactive such as fat globules, water
vacuoles, crystals in the cytoplasm and specialized
bodies known as organelles.
The specialized organelles are:
