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Chapter 3
Cells: The Basic Units of Life
Section 1: The Diversity of Cells
Section 2: Eukaryotic Cells
Section 3: The Organization of Living
Things
Ms. Jho Ann
Life Science ESL G6
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Section 1
The Diversity of Cells
Bellringer
Why do you think cells weren’t discovered until 1665? What
invention do you think made their discovery possible? Do
you think people can ever see cells with the naked eye?
Explain your answer.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Diversity of Cells
Objectives
• State the parts of the cell theory.
• Explain why cells are so small.
• Describe the parts of a cell.
• Describe how eubacteria are different from
archaebacteria.
• Explain the difference between prokaryotic cells and
eukaryotic cells.
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Section 1
The Diversity of Cells
Cells and the Cell Theory
• Finding Cells in Other Organisms In 1673, Anton van
Leeuwenhoek, a Dutch merchant, made his own
microscopes. Leeuwenhoek was the first person to see
bacteria. And he discovered that yeasts that make bread
dough rise are single-celled organisms.
• The Cell Theory All organisms are made of one or more
cells. The cell is the basic unit of all living things. All cells
come from existing cells.
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Section 1
The Diversity of Cells
Cell Size
• A Few Large Cells Most cells are small. A few, however,
are big. A chicken egg is one big cell.
• Many Small Cells There is a physical reason why most
cells are so small. Cells take in food and get rid of wastes
through their outer surface. As a cell gets larger, it needs
more food and produces more waste. Therefore, more
materials pass through its outer surface. As the cell’s
volume increases, its surface area grows too. Learn how to
calculate a cells surface area-to-volume ratio in the next
slide.
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Section 1
Math Focus: Surface Area-to-Volume Ratio
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Section 1
The Diversity of Cells
Parts of a Cell
• The Cell Membrane and Cytoplasm The cell membrane
is a protective layer that covers the cell’s surface and acts
as a barrier. Inside the cell is a fluid called cytoplasm.
• Organelles Organelles are structures that perform
specific functions within the cell.
• Genetic Material DNA is the genetic material that carries
information needed to make new cells and new organisms.
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Section 1
The Diversity of Cells
Two Kinds of Cells
• With or Without a Nucleus There are two basic types of
cells— cells without a nucleus and cells with a nucleus.
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Section 1
The Diversity of Cells
Prokaryotes: Eubacteria and Archaebacteria
• Eubacteria The most common prokaryotes are
eubacteria (or just bacteria). Bacteria are the world’s
smallest cells.
• Archaebacteria Three types of archaebacteria are heatloving, salt-loving, and methane-making.
End of Slide
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Section 1
The Diversity of Cells
Eukaryotic Cells and Eukaryotes
• What Are Eukaryotes? Organisms made of eukaryotic
cells are called eukaryotes.
• The Cell Theory Eukaryotic cells are the largest cells.
Unlike bacteria and archaebacteria, eukaryotic cells have a
nucleus. You can see other parts of a typical eukaryotic cell
on the next slide.
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Section 1
A Typical Eurkaryotic Cell
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Section 2
Eukaryotic Cells
Bellringer
List three differences between prokaryotic and eukaryotic
cells. Draw two diagrams illustrating the differences.
Write your responses in your science journal.
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Section 2
Eukaryotic Cells
Objectives
• Identify the different parts of a eukaryotic cell.
• Explain the function of each part of a eukaryotic cell.
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Section 2
Eukaryotic Cells
Cell Wall
• Supportive Structure A cell wall is a rigid structure that
gives support to a cell.
Cell Membrane
• Protective Barrier The cell membrane is a protective
barrier that encloses a cell.
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Section 2
Eukaryotic Cells
Cytoskeleton
• Web of Proteins The cytoskeleton is a web of proteins in
the cytoplasm.
Nucleus
• DNA Envelope The nucleus is a large organelle in a
eukaryotic cell. It contains the cell’s DNA, or genetic
material.
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Section 2
Eukaryotic Cells
Ribosomes
• Making Proteins Organelles that make proteins are
called are the smallest of all organelles.
Endoplasmic Reticulum
• Cell Factory The endoplasmic reticulum, or ER, is a
system of folded membranes in which proteins, lipids, and
other materials are made.
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Section 2
Eukaryotic Cells
Mitochondria
• Producing Energy A mitochondrion is the organelle in
which sugar is broken down to produce energy.
Chloroplasts
• Photosynthesis Plants and algae have chloroplasts in
some of their cells. Chloroplasts are organelles in plant and
algae cells in which photosynthesis takes place.
End of Slide
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Section 2
Eukaryotic Cells
Golgi Complex
• Packaging Proteins The organelle that packages and
distributes proteins is called the Golgi complex.
Cell Compartments
• Vesicles The bubble that forms from the Golgi complex’s
membrane is a vesicle. A vesicle is a small sac that
surrounds material to be moved into or out of a cell.
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Section 2
Eukaryotic Cells
Cellular Digestion
• Lysosomes Lysosomes are organelles that contain
digestive enzymes.
• Vacuoles A vacuole is a large vesicle. In plant and fungal
cells, some vacuoles act like large lysosomes.
End of Slide
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Section 2
Organelles and Their Functions
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Section 3
The Organization of Living Things
Bellringer
Your room might be a mess, but your body is a very
organized thing. Why can’t you use your teeth to breathe?
Why can’t you use your arm muscles to digest food? What
organs of your body serve more than one purpose? How
are those functions related or not related?
Record your answers in your science journal.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
The Organization of Living Things
Objectives
• List three advantages of being multicellular.
• Describe the four levels of organization in living things.
• Explain the relationship between the structure and
function of a part of an organism.
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Section 3
The Organization of Living Things
The Benefits of Being Multicellular
• Larger with Longer Lives multicellular organisms are
usually larger than single-celled organisms. Larger
organisms are prey for fewer predators. The life span of a
multicellular organism is not limited to the life span of any
single cell. Specialization makes the organism more
efficient.
Cells Working Together
• What Is a Tissue? A tissue is a group of cells that work
together to perform a specific job.
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Section 3
The Organization of Living Things
Tissues Working Together
• What Is an Organ? A structure that is made up of two or
more tissues working together to perform a specific
function is called an organ.
• Organs Working Together group of organs working
together to perform a particular function is called an organ
system. See how an organ system is formed on the next
slide.
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Section 3
Levels of Organization in the Cardiovascular System
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Section 3
The Organization of Living Things
Organisms
• What Is an Organism? Anything that can perform life
processes is an organism.
Structure and Function
• Close-Knit Relationship In organisms, structure and
function are related. Structure is the arrangement of parts
in an organism. Function is the job the part does.
End of Slide
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Chapter 3
Cells: The Basic Units of Life
Concept Map
Use the following terms to complete the concept map on
the next slide: prokaryotes, cells, do, do not, plants,
eubacteria, humans, bacteria, eukaryotes.
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Chapter 3
Concept Map
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Chapter 3
Concept Map
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