Download 4.1 Introduction to the Cell

4.1 Introduction to the Cell
Cell
Smallest
unit of matter that
can carry on all processes of
life
Robert Hooke (1635)
*Examined slice of
cork under a
microscope and saw
things that reminded
him of small rooms in
which Monks lived so
he called them cells.
*Development of the
microscope lead to
the discovery of the
cell
Cell Theory
*All living things are composed of
1 or more cells
*Cells are the basic unit of
structure and function in an
organism
*Cells come only from the
reproduction of existing cells
3 Characteristics of Cells
1. Size
2. Shape
3. Internal organization
1. Size
* Not all cells are alike,
they have a different
structure to fit their
function
* Body has 200different types of
cells
*Most cells are only
visible to microscope
*Most plant and animal
cells measure only 0.002
inches in diameter
*They are limited in size
by the ratio of their
surface area to their
volume. The larger this
ratio then the better the
cell can survive which
means the smaller the
cell the better for
survival.
2. Cell Shape
*Shape relates
to its function
*Nerve cells
have long
extensions to
pick up
impulses
2. Cell Shape
*Skin cells are
flat shape to
help in
covering
body surface
2. Cell Shape
 White blood cells
can change form
which allows them
to leave the blood
and go to areas
where infection is,
engulf the
infection (bacteria)
and destroy it.
3. Internal organization
Organelles
are
cell
components
which perform
specific
functions.
Organs in a
multicellular
organism carry on
functions of life
just like organelles
carry on life within
a cell.
2 Types of Cells
1. Eukaryotic cells
2. Prokaryotic cells
1. Eukaryotic Cells
*First discovered
about 1.5 billion
years ago
*Has membrane
bound nucleus
which contains the
genetic
information and
directs most of
cell’s activities
*Has membrane
bound organelles
*Has cell
membrane
*Has cytoplasm
(liquid portion
inside cell that
nourishes the
organelles)
Eukaryotic Cells
2. Prokaryotic Cells
* First discovered
about 3.5 billion
years ago
*Does not have a
membrane bound
nucleus
*Does not have
membrane bound
organelles
*First cells on earth
which did not
make their own
food
*Has cell membrane
*Examples are
bacteria and all
unicellular (onecelled) organisms.
Prokaryotic Cells