Cells
Cells are often called the “building blocks of life”. They are the basic unit of living organisms. Anything that is living is
made of cells. This means you are made of cells, trees are made of cells, an ant is made of cells, and an apple is made of
cells. Can you name other things that are made of cells?
Long ago, people did not know that cells even existed. Cells are so tiny, we cannot see them with our naked eyes. The
invention of the microscope gave people to see and discover cells for the very first time.
The first recorded discovery of cells was in 1655, when an English scientist named Robert Hooke took Anton van Leeuwenhoek's light
microscope and improved upon its design and studied a slice of cork under the lens. While looking through the microscope, he saw tiny
box-shaped sections which reminded him of the small rooms in which monks lived in at the monastery. These were called cells;
therefore Hooke decided that “cells” was the best name for his new finding. Since Hooke was only viewing something
with dead cells, he was only able to see the cell wall.
While Hooke was looking at dead cells, Anton van Leeuwenhoek, a Dutch fabric merchant, decided to see if
there was anything interesting in a drop of water. Using his microscope, he found that the drop of water housed
living organisms. These living organisms were comprised of these cells that Hooke had discovered while looking
at the cork. Leeuwenhoek called his discovery “animalcules.”
It wasn’t long until further cell discoveries were made. In 1838, German Botanist Matthias Schleiden discovered that plant parts were
made of cells. In 1839, Theodor Schwann extended Schleiden’s plant cell theory to animals. Schwann discovered that animals, just like
plants, were also comprised of tiny cells. This led to the knowledge that all living things were made of cells. In 1855, German physician
Rudolph Virchow theorized that all living cells come from other living cells.
The contributions of these people led to what we now refer to as the cell theory. This theory states:
1. All living things are made of one or more cells.
2. The cell is the smallest unit of a living organism.
3. Cells come from other cells.
Over the years, with the improvement of the microscope, scientists discovered that cells were made up of tiny parts that performed
specific functions within the cell. These tiny parts are called organelles.
Inside a Plant Cell – Organelles and their Functions
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chloroplasts
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Golgi body or Golgi apparatus
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rough endoplasmic reticulum
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ribosomes
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smooth endoplasmic reticulum
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cell membrane
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nucleolus
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vacuole
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nucleus
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lysosomes
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nuclear membrane
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cytoplasm
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mitochondrion
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cell wall
Inside a Plant Cell- Organelles and their Functions
1.
chloroplasts
These organelles are found only in plant
cells and some protists. They contain
pigments that absorb sunlight. They use the
sunlight to produce the energy they need in
order to make food (photosynthesis).
2.
rough endoplasmic reticulum
This organelle is a system of tubes and
membranes that twist and turn through the
cell which creates passages for materials to
pass through. It also has ribosomes attached
to it which allows it to aide in protein
synthesis.
3.
smooth endoplasmic reticulum
This organelle is a system of tubes and
membranes that twist and turn through the
cell which creates passages for materials to
pass through. It helps manufacture proteins
and lipids which aide in the building of the
cell membrane.
4.
nucleolus
This organelle produces ribosomal RNA and
is located inside the nucleus.
5.
nucleus
This organelle contains DNA and controls
many functions of the cell by controlling
protein synthesis.
6.
nuclear membrane
The membrane that surrounds the nucleus.
7.
mitochondrion
Inside these organelles, sugar breaks apart
as it reacts with oxygen. This releases
carbon dioxide, water, and a lot of energy.
They are often called the "powerhouses" of
the cell.
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Inside a Plant Cell- Organelles and their Functions
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Golgi body or Golgi apparatus
This organelle is a system of membranes
which receives proteins and then packages
the proteins and carbohydrates in order to be
"shipped" outside the cell.
9.
ribosomes
These organelles assemble proteins which
allow the cell to perform chemical reactions.
10.
cell membrane
A thin, flexible covering made of fat and
protein that surrounds a cell. It allows water,
food, and gases to enter a cell and wastes to
leave a cell.
11.
vacuole
A large, membrane-bound sac filled with fluid
that stores, water, food, waste, and other
substances in which the cell processes. This
gives the cell its shape.
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lysosomes
This small, ball-shaped organelle is more
common in animal cells than plant cells. It
assists in breaking down nutrients and old
cell parts.
13.
cytoplasm
This is a jellylike material between the cell
membrane and nucleus in which the
organelles are located.
14.
cell wall
Composed of cellulose and fiber, this
organelle has a rigid outer layer which
surrounds the cell membrane and protects
the cell. It gives the plant most of its structure
and allows it to stand upright. Pores in this
organelle allow materials to pass in and out
of the cell.
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Animal Cell- Organelles and their Functions
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cell membrane
9.
ribosomes
2.
rough endoplasmic reticulum
10. mitochondrion
3.
smooth endoplasmic reticulum
11. nuclear membrane
4.
nucleolus
12. centrosome
5.
nucleus
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6.
Golgi body or Golgi apparatus
14. cytoplasm
7.
microtuble
15. cilia
8.
vacuole
lysosome
Inside an Animal Cell- Organelles and their Functions
1.
cell membrane
A thin, flexible covering made of fat and
protein that surrounds a cell. It allows water,
food, and gases to enter a cell and wastes to
leave a cell.
2.
rough endoplasmic reticulum
This organelle is a system of tubes and
membranes that twist and turn through the
cell which create passages for materials to
pass through. It also has ribosomes attached
to it which allows it to aide in protein
synthesis.
3.
smooth endoplasmic reticulum
This organelle is a system of tubes and
membranes that twist and turn through the
cell which create passages for materials to
pass through. It helps manufacture proteins
and lipids which aide in the building of the
cell membrane.
4.
nucleolus
This organelle produces ribosomal RNA and
is located inside the nucleus.
5.
nucleus
This organelle contains DNA and controls
many functions of the cell by controlling
protein synthesis.
6.
Golgi body or Golgi apparatus
This organelle is a system of membranes
which receives proteins and then packages
the proteins and carbohydrates in order to be
"shipped" outside the cell.
7.
microtuble
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This organelle is like a conveyor belt inside
of a cell. They move vesicles, granules,
organelles and chromosomes by using
attachment proteins.
Inside an Animal Cell- Organelles and their Functions
8.
vacuole
A membrane-bound sac filled with fluid
that stores, water, food, waste, and other
substances in which the cell processes.
9.
ribosomes
These organelles assemble proteins
which allow the cell to perform chemical
reactions.
10.
mitochondrion
Inside these organelles, sugar breaks
apart as it reacts with oxygen. This
releases carbon dioxide, water, and a lot
of energy. They are often called the
"powerhouses" of the cell.
11.
nuclear membrane
The membrane that surrounds the
nucleus.
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centrosome
The area in the cell where microtubles
are produced.
13.
lysosome
This small, ball-shaped organelle is more
common in animal cells than plant cells.
It assists in breaking down nutrients and
old cell parts.
14.
cytoplasm
This is a jellylike material between the
cell membrane and nucleus in which the
organelles are located.
15.
cilia
Projections ("tiny hairs") from the cell,
designed to move the cell or substances
around the cell.
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