Download Cells: The Basic Unit of Life

Cells: The Basic Unit of
Life
Where does life come from?!? The answer may
seem very obvious to us now, but people who
lived long ago had some interesting ideas.
Originally, people thought that life came from the
heavens – mostly through rain. Later, as the world
became more scientific, they thought that life must
generate spontaneously.
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This was disproved
through a famous
experiment where
Aristotle placed a piece
of meat in an open jar,
and one in a closed jar.
What do you think
happen? What did the
Prove?
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The open jar quickly filled with maggotts,
flies, and worms.
The closed jar didn’t get any insects.
This meant that life had to come from
somewhere – it couldn’t generate inside the
closed jar.
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Eventually, with the
invention of the
microscope, people realized
that all living organisms are
made up of one or more
cells. All of the cells that
makes up plants have the
same structures inside. The
cells that name up animals
are also similar to each
other, but slightly different
than the plants.
Animal Cells
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All animal cells have
the same structures.
The first is the cell
membrane.
This is like, a
gatekeeper, surrounding
the whole cell and
controlling the
movement of materials
into and out of the cell.
The Nucleus
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The nucleus of the cell is
like the ‘brain’ or the
control center.
It directs all of the cells
activities. Inside the nucleus
is the nucleolus.
Also in the nucleus there are
chromosomes which
contain all of the genetic
information (the stuff passed
down by the parent cells).
The chromosomes look like
balled up strings.
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Each chromosome contains
many genes, which
determine the specific
characteristics of an
individual.
The cytoplasm is the area of
the cell where all of the
‘work’ happens. This is
where nutrients are
absorbed, transported, and
processed. You could think
of it like the blood of the
cell.
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Each Cell also has a
number of organelles.
These are kind of like
our organs. The have a
specialized purpose and
do a specific job.
Plant Cells
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Plant cells contain ALL
of the structures and
organelles found in
animal cells, plus a few
more.
Plant cells have a rigid
cell wall that surrounds
the cell membrane. This
gives the cell protection
and support.
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Plant cells also contain
larger vacuoles, which are
spaces filled with liquids
containing water, sugar,
minerals, and proteins.
They also have chloroplasts
which are organelles that are
filled with chloroplasts. This
gives plants their green
color, and helps with
photosynthesis.