Page 16 - Innovator's Science-8

slide under a microscope and draw the cells that you see in your notebook.

What did you observe? You will observe a polygonshaped structure as
shown in the given figure. These are cheek cells, which form the inner lining
of your mouth. What similarities and differences did you observe between
Science the cells of onion peel in the given figure before and human cheek cells?
Bytes

Testimony You have now seen both plant and animal cells. Let us learn more about
their structure and parts.
In 1838, German batonist
Ma hias Schleiden Cells have three main parts: a thin outer covering called the cell membrane ,
studied plant ssues and a jelly-like substance called cytoplasm , and a round structure inside called
suggested that all plants
are made of cells. A year the nucleus . The cell membrane protects the cell and controls what goes in
later, Theodor Schneann, and out, helping the cell stay safe and get the things it needs. The
a zoologist, concluded
that animals are also cytoplasm fills up the space between the membrane and nucleus; it holds
made up of cells. all the cell's parts and is where most of the work in the cell happens, like
Together, their breaking down food and making energy. The nucleus is like the cell's control
observa ons formed the
basis of the cell theory, center; it has the cell's DNA and directs all the cell's activities, like growth
which states that cells are and making new cells. Sometimes, in certain cells like onion skin cells, there
the basic units of life.
Later, Rndolf Virchow exists an extra thick outer layer called the cell wall that gives strength and
added that new cells arise support. All these parts work together to keep the cell alive and healthy,
only from pre-exis ng which is very important for the life of every plant, animal, and person.
cells.
The cell membrane is a thin covering that surrounds the cytoplasm and

nucleus, keeping the inside of the cell safe and separate from other cells.
This membrane has tiny pores that let
important materials, like nutrients, move
into the cell and allow waste to go out,

helping the cell function properly. Inside the
cell, the cytoplasm contains different
chemicals and bits, such as carbohydrates,
proteins, fats, and minerals, which the cell

needs to live and grow. Most of the
important life activities happen in the
cytoplasm, making it a vital part of the cell's
structure and survival.
Cell membrane
The nucleus works like the control center of the cell. It manages everything
the cell does, such as how it functions and how it grows. In plant cells, the

cell wall acts like a strong outer layer that gives the cell its shape, strength,
and protection. Because of this, plant cells fit closely together and appear
firm and rigid, helping the plant stand upright and stay strong.

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Science-8