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The
Parts of Cells |
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A cell is an amazing package made
of a cell membrane, a
nucleus, and many other
structures. Most of the things your
body does are really done inside cells. For
example, you grow
when your cells grow larger and divide. Your arm moves
because
small fibers are moving inside muscle cells. |
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All cells have some of the same parts,
and many parts have
similar jobs. Cells have
the same needs as your whole body
has. For example, your body needs an outside
covering of skin,
a control system of nerves, a support system of bones, and
places
to store food and wastes in the digestive system. Some
cell parts can be compared
to these larger structures in your
body. Only a few of the parts of an animal cell are
pictured here. |
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The cell membrane
surrounds a cell, holding the parts of the cell together. It allows
needed materials, such as sugar, water, and oxygen, to enter the
cell. It allows certain
other materials, such as carbon dioxide and other waste products,
to exit. |
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The nucleus
is the part of the cell that contains chromosomes. Chromosomes are
made of materials including a chemical called DNA (deoxyribonucleic
acid).
DNA is
a chemical shaped like a twisted ladder. Chromosomes carry the instructions
for the
cell to do its jobs. By telling every cell how to do its jobs, chromosomes
control how
the whole body grows and changes. |
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Every chromosome has small sections
of DNA called genes.
Genes are made of DNA.
Each gene carries a single unit of
information. Almost every cell in your body has the
same set
of thousands of genes. Heredity is the process of passing
these genes
from one generation to the next. |
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Plant
Cells |
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Plant cells have all
the parts seen
in the animal cell. Plant cells also
have a few parts not found in
animal cells. |
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A tough
cell wall surrounds
the
cell membrane. The cell wall is stiff,
unlike the thin cell membrane. Cell
walls give plant cells extra support
and protection. |
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Chloroplasts
use the
energy in sunlight to turn water and carbon dioxide
into oxygen and sugar. Plant cells use oxygen
and sugar for respiration.
Chloroplasts give plants their green color. |
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This
plant cell is magnified
about 6,000 times. |
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