Name ___________________________ Class ________ Date ___________
TEKS
Biology
Lesson 4A
TEKS 4A Compare and contrast prokaryotic and eukaryotic cells.
TEKS Lesson 4A:
Prokaryotic and Eukaryotic Cells
What are the two types of cells?
Cells come in an amazing variety of shapes and sizes, but all cells contain DNA. Also, all cells are
surrounded by a thin flexible barrier called a cell membrane. There are two basic categories of cells
based on whether they contain a nucleus. The nucleus (plural: nuclei) is a large membrane-enclosed
structure that contains DNA. Eukaryotes are cells that enclose their DNA in nuclei. Prokaryotes are
cells that do not enclose their DNA in nuclei.
How do prokaryotes and eukaryotes compare?
In addition to both having DNA and a cell membrane, prokaryotes and eukaryotes have a couple of
other things in common. For example, all cells have ribosomes, small particles of RNA and protein
that assemble proteins. Ribosomes are found throughout the cytoplasm of both eukaryotes and
prokaryotes. In addition, most prokaryotes and many eukaryotes have cell walls. A cell wall is
a strong supporting layer that surrounds a cell’s membrane. Finally, all cells grow, divide, and
maintain homeostasis. A typical prokaryotic (left) and eukaryotic (right) cell are shown below.
How do prokaryotes and eukaryotes contrast, or differ?
Although they share a few characteristics, prokaryotes and eukaryotes are very different. In fact, it should
usually be very easy to distinguish a prokaryote from a eukaryote using even the most basic microscope.
Size and Complexity In general, prokaryotic cells are much smaller and less complex than eukaryotic
cells. Further, almost all prokaryotic organisms, such as bacteria, are unicellular. So, if an organism is
multicellular, it is almost always made up of eukaryotic cells. Cells contain a variety of specialized
structures called organelles that carry out specific cellular functions. Ribosomes, found in both
prokaryotes and eukaryotes, are an example of an organelle. In general, eukaryotes contain far more
organelles than prokaryotes. In addition to ribosomes, for example, most eukaryotic cells contain
endoplasmic reticulum, Golgi apparatus, and mitochondria. A simplified prokaryotic and eukaryotic cell
are shown on the next page.
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Name ___________________________ Class ________ Date ___________
TEKS
Biology
Lesson 4A
Cell Division While all cells grow and divide, prokaryotes and eukaryotes do so differently.
Prokaryotes divide by binary fission, a form of asexual reproduction that results in two genetically
identical daughter cells. Eukaryotic cells undergo a two-step cell division process: mitosis followed by
cytokinesis. Mitosis is division of the nucleus. Cytokinesis is division of the cytoplasm. Cytoplasm
includes all of a eukaryotic cell’s contents outside the nucleus.
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Name ___________________________ Class ________ Date ___________
TEKS
Biology
Lesson 4A
Classification Prokaryotes and eukaryotes are classified very differently.
Prokaryotes make up two of the three domains of life: Bacteria and Archaea. These
domains correspond to the kingdoms of Eubacteria and Archaebacteria. Eukaryotes
make up the third domain of life, Eukarya. Eukarya consists of four kingdoms:
Protista, Fungi, Plantae, and Animalia. As an indication of how varied prokaryotes are,
the two prokaryotic domains are less similar to each other than either is to domain
Eukarya.
Three Domains
Domain
Organism Characteristics
Kingdoms
Included in
Domain
Bacteria
Prokaryotes with cell walls
made up of petidoglycan
Eubacteria
Archaea
Prokaryotes whose cell walls
do not contain peptidoglycan
Archaebacteria
Eukarya
Eukaryotes
Protista, Fungi,
Plantae, Animalia
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TEKS
Name ___________________________ Class ________ Date ___________
Biology
Lesson 4A
Lesson Check
1. Learn Vocabulary The chart below shows a few of the key terms from the lesson with their
definitions. Complete the chart by writing a strategy to help you remember the meaning of each term.
Term
Definition
Cell
Basic unit of life
Cell membrane
Thin flexible barrier that
separates the cell from its
environment
Eukaryote
Cell with DNA that is enclosed
in a nucleus
Nucleus
A membrane-enclosed cell
structure that contains most of
a eukaryotic cell’s DNA
Prokaryote
Cell with DNA not enclosed in a
nucleus
How I’m Going to Remember
the Meaning
I’ll think of cells in a jail that are
small rooms in a building.
2. Compare and Contrast Compare and contrast prokaryotic and eukaryotic cells by completing
the table.
Prokaryotic Cell
Cell membrane
Eukaryotic Cell
yes
Nucleus
Cell size
Complexity
larger
simpler
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Name ___________________________ Class ________ Date ___________
TEKS
Biology
Lesson 4A
Fill in the blanks.
3. Review Your body is made up of ________________________ cells.
4. Review Bacteria are unicellular ________________________ cells.
5. Explain What is the function of ribosomes? ____________________________________________
_______________________________________________________________________________
6. Review What is a cell wall, and what types of cells have one? _____________________________
_______________________________________________________________________________
For Questions 7–10, write True if the statement is true. If the statement is false, change the underlined
word or words to make the statement true.
_____________ 7. Compare and Contrast All cells grow and divide.
_____________ 8. Review Cell division in prokaryotes is called mitosis.
_____________ 9. Review Cytokinesis is one stage of cell division in prokaryotes.
____________ 10. Review Prokaryotic cell division results in two genetically different cells.
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