Name: ____________________ Date: ____________________
Prokaryotes and Eukaryotes Quick Read
All living things are made of cells, the
basic building blocks of life. Cells are so
important that they're called the
structural and functional units of all living
organisms. There are two main types of
cells: prokaryotic and eukaryotic. These
two types of cells differ drastically from
each other.
The word "prokaryote" comes from
Greek words meaning "before nuclei".
Prokaryotes are single-celled organisms
that don't have a nucleus or other
membrane-bound organelles. This means their DNA isn't stored inside a special compartment.
Prokaryotes are ancient, with fossil records going back 3.5 billion years. They were some of the first
life forms on Earth. Examples of prokaryotes are bacteria and archaea.
Prokaryotic cells are generally smaller and simpler than eukaryotic cells. They have a capsule that
acts as a protective coat. This capsule helps prevent phagocytosis, which is when a cell gets
engulfed by another cell. Prokaryotes reproduce asexually through a process called binary fission.
They also have horizontal gene transfer, which means they can share genetic material with each
other.
Eukaryotes, on the other hand, are organisms whose cells do have a nucleus. The word "eukaryote"
comes from Greek words meaning "true" or "good" and "kernel". This nucleus is like a control center
that holds the cell's DNA. Eukaryotic cells also have other membrane-bound organelles, like the
endoplasmic reticulum and the Golgi apparatus. Animals, plants, fungi, and seaweeds are all
eukaryotes.
Eukaryotic cells are more complex than prokaryotic cells. Their DNA is linear and found inside the
nucleus. They also have mitochondria, which are like tiny power plants that produce energy for the
cell. Eukaryotes can be unicellular (single-celled) or multicellular (made of many cells). Unicellular
eukaryotes are sometimes called protists. Eukaryotes can reproduce asexually through mitosis or
sexually through meiosis and fertilization.
Scientists believe that eukaryotes evolved from prokaryotes through a process called endosymbiosis.
This is when one prokaryotic cell engulfed another and they began to live together in a symbiotic
relationship. For example, mitochondria are thought to have once been free-living bacteria that were
engulfed by another cell. The host cell benefited from the energy produced by the mitochondria, and
the mitochondria benefited from the protected environment.
The main difference between prokaryotes and eukaryotes is the presence of a nucleus and other
membrane-bound organelles in eukaryotes. Prokaryotes are simpler and smaller, while eukaryotes
are more complex and larger. Prokaryotes reproduce asexually, while eukaryotes can reproduce both
asexually and sexually.
Even though prokaryotes are smaller and simpler, they are incredibly important. They play a vital role
in many ecosystems, and they were the first life forms on Earth. Eukaryotes, with their complex cells
and ability to form multicellular organisms, have also shaped the world we live in.
In conclusion, prokaryotes and eukaryotes are the two main types of cells, each with its own unique
characteristics. Prokaryotes are simple and lack a nucleus, while eukaryotes are complex and have a
nucleus and other organelles. Both types of cells are essential for life on Earth.
________________________________________________________________________________
_________________
After you’ve read through the article, complete the following tasks:
Highlight the following (highlight where it says it in the text):
The two main types of cells
Examples of prokaryotes
Examples of eukaryotes
Which cell is more complex?
What is endosymbiosis?
Underline the following (underline where it says this in the text):
Do prokaryotes have a nucleus?
Do prokaryotes have organelles?
The size of prokaryotes
How many cells are prokaryotes made of?
Box the following (box where it says this in the text):
Do eukaryotes have a nucleus?
Do eukaryotes have organelles?
How many cells are eukaryotes made of?
0
