Download You may know that all living things are made of tiny units called cells

You may know that all living things are made of tiny units called
cells. But did you know that different types of living things have
different types of cells? Not all cells are the same. Living things such
as people, birds, fish, and insects are made of animal cells. Living
things such as flowers, grass, trees, and mosses are made of plant
cells.
Animal cells are surrounded by a thin and flexible cell membrane.
Because the cell membrane is flexible, animal cells can have many
different shapes. This is why cells in your body can look so different.
Some cells are long with thread-like extensions. Other cells are
round and compact. Cells in your body have different shapes so that
they can do different jobs.
Plant cells are surrounded by a cell membrane. However, they are
also surrounded by a strong and thick cell wall. Cell walls are rigid
and surround the cell membranes. Because cell walls are not very
flexible, they give all plant cells a similar box-like shape. Cell walls
give support to plants. They allow plants to grow straight up.
Because of cell walls, trees can grow hundreds of feet tall.
Animal cells are also different from plant cells because
animal cells cannot make food. All animals must eat food to
survive. However, plants can make their own food. Plants
have structures called chloroplasts inside their cells.
Chloroplasts capture sunlight. Plant cells use energy from
sunlight to make food. Without sunlight, plants would not
be able to make food. Animals do not have chloroplasts
inside their cells.
Every plant and animal cell also has a part called the
nucleus. A nucleus controls all the activities that take place
inside a cell. However, the cells of bacteria do not have a
nucleus. Bacteria cells are less complicated than plant and
animal cells. However, all bacteria cells are surrounded by a cell
membrane. Some bacteria cells also have cell walls and
chloroplasts.