Science Workbook
Cell Structure Lesson
Day 1
Cells Day 1
Inquiry Lab: Is It Alive?
Sometimes, it is difficult to tell living things from nonliving things. To be considered
alive, something must have all of the characteristics of life.
Procedure
1. With your group, discuss some characteristics you could look for to tell whether
something is living or nonliving.
2. Examine an assortment of objects given to you by your teacher.
3. Make a table that has three columns. In the first column, describe each of the
objects. In the second column, state whether each object is living or nonliving.
4. In the third column, write down the characteristics of life that you observed in
each object.
Analysis
1. Identify characteristics of life that are difficult to see during a brief observation
like this one.
______________________________________________________________
______________________________________________________________
______________________________________________________________
2. Identify an object or material (not necessarily among your samples) that
undergoes growth but that has never been alive.
______________________________________________________________
______________________________________________________________
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Cell Structure Lesson
Introduction to Cells
After reviewing the list of objects you compiled in the Is It Alive? Lab, work with a
partner and make two new lists: those items comprised of cells and those items not
comprised of cells. Give a rationale for each answer.
Cells
No Cells
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Cell Structure Lesson
Reference: Units of length
Reference: Cell size
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Cell Structure Lesson
BIG IDEAS READING
The Discovery of Cells
In 1665, Robert Hooke, an English scientist, used a crude
microscope to look at a thin slice of cork. His microscope
could magnify objects to only 30 times their normal size.
Hooke saw many “little boxes” in the cork. They
reminded him of the small rooms in which monks lived,
so he called them cells. Hooke later discovered cells in the
stems and roots of plants. Ten years later, Anton van
Leeuwenhoek, a Dutch scientist, used a more powerful microscope that could magnify objects 300-fold.
He discovered many living creatures in pond water. He named them animalcules, or “tiny animals.”
Today, we know that they were not animals. They were single-celled organisms.
Cell Theory It took more than 150 years for scientists to fully appreciate the discoveries of Hooke and
Leeuwenhoek. By the 1830s, microscopes were powerful enough to resolve structures only 1 µm apart. In 1838,
Matthias Schleiden, a German botanist, concluded that cells make up every part of a plant. A year later,
Theodor Schwann, a German zoologist, discovered that animals are also made up of cells. In 1858, Rudolph
Virchow, a German physician, proposed that cells come only from the division of existing cells. The
observations of Schleiden, Schwann, and Virchow form the cell theory:
• All living things are made up of one or more cells.
• Cells are the basic units of structure and function in organisms.
• All cells arise from existing cells.
The cell theory has withstood the rigorous examination of cells by scientists equipped with today’s highpowered microscopes. As new tools and techniques are invented, scientists will learn more about the
characteristics of cells.
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Cell Structure Lesson
What they are REALLY saying is ___?
Use the space below to provide a short description of what each of the sections from the Big Ideas
Reading is REALLY saying. Please write these summaries in your own words.
Section #
What they are REALLY saying…in your words
1: The
Discovery
of Cells
2: Cell
Theory
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Cell Structure Lesson
BIG IDEAS READING
Cell Features All cells—from bacteria to those in a berry, bug, or bunny—share common structural features.
All cells have a cell membrane, cytoplasm, ribosomes, and DNA. The cell membrane is the cell’s outer
boundary. It acts as a barrier between the outside environment and the inside of the cell. The cytosol, the fluid
inside the cell, is full of dissolved particles. The cytoplasm includes this fluid and almost all of the structures
that are suspended in the fluid. Many ribosomes are found in the cytoplasm. A ribosome is a cellular structure
on which proteins are made. All cells also have DNA, the genetic material. DNA provides instructions for
making proteins, regulates cellular activities, and enables cells to reproduce.
Features of Prokaryotic Cells The bacterium shown in the figure below is an example of a prokaryote, an
organism that is a single prokaryotic cell. A prokaryotic cell is quite simple in its organization. The genetic
material is a single loop of DNA, which looks like a tangled string and usually lies near the center of the cell.
Ribosomes and enzymes share the cytoplasm with the DNA.
Image Caption: The cytoplasm of a prokaryotic cell is made up of everything that is inside the cell membrane, including
ribosomes and a loop of DNA.
Prokaryotic cells have a cell wall that surrounds the cell membrane and that provides structure and support.
Some prokaryotic cell walls are surrounded by a capsule, a structure that enables prokaryotes to cling to
surfaces, including teeth, skin, and food. Scientists think that the first prokaryotes may have lived 3.5 billion
years ago or more. For millions of years, prokaryotes were the only organisms on Earth. They were very simple
and small (1 to 2 µm in diameter). Like their ancestors, modern prokaryotes are also very small (1 to 15 µm),
and they live in a wide range of habitats. Prokaryotes make up a very large and diverse group of cells.
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Cell Structure Lesson
Features of Eukaryotic Cells A eukaryote is an organism that is made up of one or more eukaryotic
cells. Some eukaryotes live as single cells. Others are multicellular organisms. In fact, all multicellular
organisms are made up of eukaryotic cells. Because of their complex organization, eukaryotic
cells can carry out more specialized functions than prokaryotic cells can.
Primitive eukaryotic cells first appeared about 1.5 billion years ago. As shown in the animal cell in the
figure below, a eukaryotic cell contains compartments that are separated by membranes. The cell’s
DNA is housed in an internal compartment called the nucleus.
Image Caption: The cytoplasm of a eukaryotic cell is made up of many different structures that are surrounded by
membranes.
In addition to having a membrane, cytoplasm, ribosomes, and a nucleus, all eukaryotic cells have
membrane-bound organelles. An organelle is a structure that carries out specific activities inside the cell.
The animal cell in the figure above shows many of the organelles found in eukaryotic cells. Each organelle
performs distinct functions. Many organelles are surrounded by a membrane. Some of the membranes
are connected by channels that help move substances within the cell.
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Cell Structure Lesson
What they are REALLY saying is ___?
Use the space below to provide a short description of what each of the sections from the Big Ideas
Reading is REALLY saying. Please write these summaries in your own words.
Section #
What they are REALLY saying…in your words
1: Cell
Features
2: Features
of
Prokaryotic
Cells
3: Features
of
Eukaryotic
Cells
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Cell Structure Lesson
BIG IDEAS LECTURE
As the teacher lectures, use the space below to take notes.
Questions
(write down any questions you may
have here)
Notes
(Place your notes here)
CELL MEMBRANE =
CYTOPLASM =
RIBOSOME =
PROKARYOTE =
EUKARYOTE =
NUCLEUS =
ORGANELLE =
DNA =
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Cell Structure Lesson
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Cell Structure Lesson
Day 1 Review
Using what you have written in your notebook today, answer the following review questions in
the space provided…
1. List the three parts of cell theory.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
2. Describe the importance of a cell’s surface area-to-volume ratio.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
3. Compare the structure of a eukaryotic cell with that of a prokaryotic cell.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
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Cell Structure Lesson
Cells Day 1
Homework
Section: Introduction to Cells
In the space provided, write the letter of the description that best matches
each term.
_____ 1. cell membrane
_____ 2. cytoplasm
_____ 3. nucleus
_____ 4. ribosome
a. cell structure with its own membrane that
stores the cell’s genetic material
b. cell structure where proteins are made
c. layer that forms the boundary between the
inside and outside of a cell
d. the fluid inside a cell and all of the structures
within the fluid
Write ct next to all of the statements that are part of the cell theory. Leave the other statements blank.
_____ 5. Cells come in many different sizes.
_____ 6. All cells arise from existing cells.
_____ 7. A cell’s shape reflects its function.
_____ 8. All living things are made up of one or more cells.
_____ 9. Cells are the basic units of structure and function in organisms.
In the space provided, write the letter of the phrase that best answers each question.
_____ 10. Who first discovered cells?
a. scientists who wanted to confirm the cell theory
b. scientists looking at skin cells through microscopes
c. scientists looking at living plants through microscopes
d. scientists looking at cork and pond water through microscopes
_____ 11. Why can eukaryotes carry out more specialized functions than prokaryotes can?
a. Eukaryotes have more organelles.
b. Prokaryotes have more organelles.
c. Eukaryotes are bigger.
d. Prokaryotes are bigger.
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