Download The Cell

The Cell
Teacher’s Guide
High/Middle
School
Editors:
Brian A. Jerome, Ph.D.
Stephanie Zak Jerome
Assistant Editors:
Heidi Berry
Stephanie Rogers
Anneliese Brown
Visual Learning Company
Brandon, Vermont
1-800-453-8481
www.visuallearningco.com
The Cell
Reviewers:
Mary Cahill
Potomac Middle School
Mclean, Virginia
Wasim Chowdhury, Ph.D.
Department of Biological Sciences
University of Maryland
Baltimore, Maryland
Susan Hurstecalderone
Holy Cross
Chevy Chase, Maryland
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The Cell
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The Cell
Table of
Contents
Page
National Standards Correlations
6
Student Learning Objectives
7
Assessment
8
Introducing the Video
9
Video Viewing Suggestions
9
Video Script
11
Answers to Student Assessments
16
Answers to Student Activities
17
Assessment and Student Activities Masters
18
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The Cell
A Message from our
Company . . .
Dear Educator:
Thank you for your interest in the educational videos produced by the
Visual Learning Company. We are a Vermont-based, family owned and
operated business specializing in the production of quality educational
science videos and materials.
We have a long family tradition of education. Our grandmothers graduated
from normal school in the 1920’s to become teachers. Brian’s mother was
an elementary teacher and guidance counselor, and his father was a high
school teacher and superintendent. This family tradition inspired Brian to
become a science teacher, and to earn a Ph.D. in education, and lead
Stephanie to work on science educational programs at NASA.
In developing this video, accompanying teacher’s guide, and student
activities, our goal is to provide educators with the highest quality materials,
thus enabling students to be successful. In this era of more demanding
standards and assessment requirements, supplementary materials need to be
curricular and standards based - this is what we do!
Our videos and accompanying materials focus on the key concepts and
vocabulary required by national and state standards and goals. It is our
mission to help students meet these goals and standards, while experiencing
the joy and thrill of science.
Sincerely,
Brian and Stephanie Jerome
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The Cell
National Standards
Correlations
National Science Education Standards
(Content Standards: 5-8, National Academy of Sciences, c. 1996)
Science as Inquiry - Content Standard A:
As a result of activities in grades 5-8, all students should develop:
• Abilities necessary to do scientific inquiry
• Understandings about scientific inquiry
Life Science - Content Standard C:
As a result of their activities in grades 5-8, all students should develop
an understanding of how:
• All organisms are composed of cells- the fundamental unit of life.
Most organisms are single cells; other organisms, including humans,
are multicellular.
• Cells carry on the many functions needed to sustain life. They grow
and divide, thereby producing more cells. This requires that they take
in nutrients, which they use to provide energy for the work that cells
do and to make the materials that a cell or an organism needs.
Benchmarks for Science Literacy
(Project 2061 - AAAS, c. 1993)
The Living Environment - Cells (5C)
By the end of the 8th grade, students should know that:
• All living things are composed of cells, from just one to many millions,
whose details usually are visible only through a microscope. Different
body tissues and organs are made up of different kinds of cells. The
cells in similar tissues and organs in other animals are similar to those in
human beings but differ somewhat from cells found in plants.
• Cells continually divide to make more cells for growth and repair.
Various organs and tissues function to serve the needs of cells for food,
air, and waste removal.
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The Cell
Student Learning
Objectives
Upon viewing the video and completing the enclosed student
activities, students should be able to do the following:
•
Understand that all life depends on cells;
•
Identify the three principles of the cell theory and recognize
its importance in studying cells;
•
Understand that scientists use microscopes to make new
discoveries about cells;
•
Differentiate between a light microscope and an electron
microscope;
•
Differentiate between living cells and non-living cells;
•
Identify and explain the function of the different structures
found in cells, including cell wall, chloroplast, nucleus,
nucleolus, cytoplasm, endoplasmic reticulum, ribosome, golgi
apparatus, mitochondria, vacuole, and lysosome;
•
Differentiate between the organization of a plant cell and an
animal cell; and
•
Discuss the specific functions that the different organelles in a
cell perform.
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The Cell
Assessment
Preliminary Test:
The Preliminary Test, provided in the Student Masters section, is an
assessment tool designed to gain an understanding of student preexisting
knowledge. It can also be used as a benchmark upon which to assess
student progress based on the objectives stated on the previous pages.
Video Review:
The Video Review, provided in the Student Masters section, can be used as
an assessment tool or as a student activity. There are two main parts. The
first part contains questions titled “You Decide” that can be answered during
the video. The second series of ten questions consists of a video quiz to be
answered at the conclusion of the video.
Post-Test:
The Post-Test, provided in the Student Masters section, can be utilized as an
assessment tool following student completion of the video and student
activities. The results of the Post-Test can be compared against the results of
the Preliminary Test to assess student progress.
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The Cell
Introducing the
Video
Cells are the building blocks of life. All living organisms contain cells.
Explain to the students that although cells are microscopic, each one contains many organelles that allow the cell to function. Before showing the
video, ask students to name the parts of a cell that they already know. The
most
commonly known parts of a cell include the nucleus, cell membrane, and the
cell wall. Have one volunteer write the list on the chalkboard. After
viewing the video, have students add to the list on the board other
organisms not mentioned before the showing. Along with listing the names
of the organelles, have the students explain how each organelle enables the
cell to function.
Video Viewing
Suggestions
You may want to photocopy and distribute the Student Master, “Video
Review.” You may choose to have your students complete this Master while
viewing the program or to do so upon its conclusion.
The program is approximately 20-minutes in length and includes a tenquestion video quiz. Answers are not provided to the Video Quiz on the
video, but are included in this teacher’s guide. You may decide to grade
student quizzes as an assessment tool or to review the answers in class.
The video is content-rich with numerous vocabulary words. For this reason
you may want to periodically stop the video to review and discuss new
terminology and concepts.
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The Cell
Student Assessments
and Activities
Assessment Masters:
•
Preliminary Test
•
Video Review
•
Post-Test
Student Activity Masters:
•
The Animal Cell
•
The Plant Cell
•
The Cell Theory and Microscopes
•
Seeing Cells
•
Vocabulary of The Cell
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The Cell
Video ScriptThe Cell
1. All living things have one very important thing in common. They all possess tiny
structures that can’t be seen with the naked eye.
2. What are these tiny structures?
3. Flowers possess them.
4. Plants and trees rely on these structures to grow tall and…
5. …to convert radiant energy from the sun to simple sugars that contain chemical
energy.
6. Fish use them to carry out their lives in water,…
7. ...and even large animals such as this pelican…
8. …and this sea lion depend on these structures to move, grow, and reproduce.
9. What are the structures on which all life depends? Here is one more clue: they
often are called the building blocks of life!
10. These structures are called cells.
11. During the next few minutes we are going to take a look at the general characteristics
of cells, their designs,…
12. …and the activities they perform.
13. We are also going to take a look at how cells help human beings carry out their lives.
14. Graphic Transition - Seeing the Invisible
15. Exactly what are cells and how important are they?
16. As we have stated, all life depends on cells. The human body contains not only
millions of cells, but hundreds of different kinds of cells as well.
17. Most cells are too small to be seen with the naked eye.
18. For example, this small drop of water contains dozens of single-celled organisms not
visible to the naked eye.
19. Using a tool called a microscope, however, these invisible cells become visible.
20. The first microscopes, which contained just a single lens, were similar to a
magnifying glass.
21. But in 1590 a man who made reading glasses decided to put two lenses together in a
tube and made the first compound microscope.
22. Today, compound light microscopes are widely used. These microscopes let light
pass through an object on a glass slide and then through two or more lenses.
23. Convex lenses enlarge the image and bend the light toward the eye.
24. The most common compound light microscopes magnify objects up to 430 or 1000
times their original size, while those with more powerful lenses have even greater
magnification power.
25. Objects that are too small to be seen with a compound light microscope can only be
viewed with an electron microscope, which has the ability to magnify images up to
one million times their original size.
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The Cell
Script
26. Rather than using lenses to bend light, electron microscopes use magnetic fields to
bend beams of electrons.
27. This electron microscope is called a scanning electron microscope.
28. Scanning electron microscopes are used to study the outside of objects.
29. Graphic Transition- Discovering the Cell
30. Early scientists did not have the high-powered microscopes we use today.
31. Instead, they utilized simple microscopes, such as this one, to explore the
microscopic world.
32. One such scientist was the English biologist Robert Hooke
33. You Decide! What’s the object Hooke saw under his microscope?
34. In 1663, Hooke took a piece of cork, cut a very thin slice, and viewed it under the
microscope.
35. Looking at the cork he discovered tiny square-shaped forms. He called these
structures cells.
36. What Hooke was seeing was not living cells but the remaining cell walls of dead
plant cells.
37. Around the same time, a Dutch scientist named Anton van Leeuwenhoek was also…
38. …using a simple microscope to look at living microscopic organisms.
39. He was the first to discover single-celled organisms we know today as bacteria.
40. Graphic Transition- The Cell Theory
41. In 1838 a German botanist, Matthias Schleiden, used the microscope to study…
42. … parts of plants.
43. Schleiden concluded that plants were made of cells.
44. One year later, scientist Theodor Schwann, who had been looking…
45. …at different animal cells, concluded that…
46. …all animals, too, are made of cells.
47. Together, Schleiden and Schwann concluded that all living things are made of cells.
48. In the mid-1850’s, a doctor by the name of Rudolph Virchow stated that new cells
do not form on their own.
49. He stated that cells divide to form new cells.
50. In other words, new cells come from previously existing cells.
51. The combined discoveries of Schleiden, Schwann, and Virchow led to what we
know today as the cell theory.
52. The cell theory is a fundamental principle of biology and has three major parts.
53. First, it states that all living organisms are made of one or more cells.
54. This ranges from single-celled organisms, such as this bacteria,…
55. …to large organisms such as this horse.
56. Second, the cell theory states that cells are the basic units of structure and function
in all organisms.
57. This means that there is no life without cells.
58. Third, the cell theory states that all cells come from previously existing cells.
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The Cell
Script
59. As previously stated, new cells do not just magically appear, but come from other
cells when they divide.
60. These three main concepts make up the cell theory.
61. Graphic Transition – Organization of the Cell
62. Most cells are smaller than the head of this pin.
63. But, believe it or not, cells are made up of even smaller parts called organelles.
64. Organelles are the structures within cells that break down food, move water, and
store nutrients.
65. All parts of a cell are extremely important in carrying out functions in both plants and
animals.
66. While both plant and animal cells contain many similar cell structures, there are
some distinct differences between plant and animal cells.
67. One difference between plant and animal cells is the structure that surrounds the cell.
68. Plant cells are surrounded by a relatively rigid cell wall. The cell wall is made of
cellulose, a strong and tough material.
69. Cell walls enable trees to stand straight and tall.
70. You Decide! Do animals possess a cell wall?
71. Animal cells do not possess a cell wall, possessing only a cell membrane.
72. Plants also possess a cell membrane, but it lies inside the cell wall.
73. In both plants and animals, the cell membrane allows only certain materials to flow
into and out of the cell.
74. For example, food and oxygen move through the cell membrane into the animal
cell,...
75. …while waste products go through the membrane to exit the cell.
76. Another difference between plant and animal cells is that plants possess structures
called chloroplasts.
77. Chloroplasts are organelles that convert light energy into chemical energy that the
cell uses to carry out its activities.
78. Chloroplasts enable plants to produce their own food from the energy of the sun
79. Animal cells don’t have chloroplasts. Therefore animals need to obtain their energy
by eating food made by other living things, such as fruits, vegetables and meats.
80. Let’s now take a look at some of the other structures found in cells
81. Graphic Transition – The Nucleus
82. Our brains are the control centers of our bodies.
83. The brain guides us through all the activities we take part in during the course of a
day.
84. Cells, too, have a control center, called the nucleus.
85. The nucleus acts as the cell’s brain control center, regulating all cellular activities.
86. The nuclear membrane surrounds and protects the nucleus.
87. Like the cell membrane, the nuclear membrane allows only certain materials to pass
in and out of the nucleus.
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The Cell
Script
88.
89.
90.
91.
92.
93.
Also located in the nucleus is a small, dark, round structure called the nucleolus.
The nucleolus is where RNA is built and ribosome pieces are created.
Graphic Transition- Cytoplasm
You Decide! What is the material seen flowing through this cell?
If you said water, then you are close. The liquid is called cytoplasm.
Cytoplasm contains a large amount of water as well as many chemicals and
structures that help carry out the life processes of the cell.
94. Within the cytoplasm are many organelles that we’ll now explore.
95. Graphic Transition- Endoplasmic Reticulum and Ribosomes
96. This network of roads used to transport cars and trucks is like a cell organelle...
97. ...called the endoplasmic reticulum.
98. Its function is to transport materials such as proteins throughout the cell, or in and
out of the cell.
99. The endoplasmic reticulum forms a series of tubular passageways, seen here.
100. Attached to the inner surface of the endoplasmic reticulum and scattered in the
cytoplasm are small, round structures called ribosomes.
101. Ribosomes play a very important role in the cell because they contain a
chemical,called RNA,that directs the production of proteins.
102. Proteins speed up chemical reactions in the cell, as well as control cell growth
and repair.
103. Graphic Transition- Golgi Bodies and Mitochondria
104. This loading dock contains material that has been packaged …
105. …and will soon be transported to other locations.
106. Golgi bodies, or the Golgi Apparatus, are stacks of membrane-covered sacs that
package and move particles to the outside of the cell.
107. The Golgi Apparatus can be thought of as the cell’s conveyor belt, transporting
material.
108
This electrical generating plant provides energy for thousands of people.
1
109. Similarly, structures called mitochondria are the powerhouses of the cell.
110. These rod-shaped structures seen here supply most of the energy for the cell.
111. They break down food to produce large amounts of energy.
112. Muscle cells, which expend large amounts of energy, also contain many
mitochondria.
113. Graphic Transition- Vacuoles and Lysosomes
114. This silo, located on this farm, stores food that will…
115. …eventually be fed to cows.
116. Similarly, vacuoles located in the cell store food and other materials for later use by
the cell. They can also store waste.
117. In plant cells, vacuoles are the main area where water is stored.
118. The last cell organelles we’ll explore are lysosomes.
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The Cell
Script
119. Lysosomes, seen here, contain enzymes. Enzymes break down large food particles
into smaller particles, which are then burned in the mitochondria to provide energy
for the cell.
120. Lysosomes also digest old parts of the cell when they lose their effectiveness.
121. For example, as this tadpole grows, its tail cells are slowly digested by the
lysosomes until the tail disappears.
122. You Decide! What do lysosomes do with the old tail cells?
123. This material is reused to make new body parts to become an adult frog.
124. Graphic Transition- Summing Up
125. During the past few minutes we have explored many different characteristics of
cells.
126. We studied how different scientists have made many different discoveries about
cells using microscopes...
127. ...and how they developed the cell theory, which states that...
128. ...all living things are made of cells, and . . .
129. ...that cells are the basic unit of structure and function in living things . . .
130. ...and that new cells come from previously existing cells.
131. We also explored some of the important differences between plant and animal cells.
132. Finally, we took a look at some of the important organelles in cells, including the
nucleus, . . .
133. ...the endoplasmic reticulum, and ribosomes, . . .
134. ...golgi bodies and mitochondria, . . .
135. ...as well as vacuoles and lysosomes.
136. So the next time you see a plant . . .
137. ...or animal, or see other...
138. ...people, think about how all these living things contain cells. You just might look
at your world a little differently.
Video Quiz
Fill in the correct word when you hear this tone. Good luck and let’s get started.
1. All living things possess _____.
2. Robert Hooke discovered cells while looking at a piece of ____.
3. ________ microscopes use magnetic fields to magnify objects.
4. All cells come from ________ _____.
5. _______ are structures within cells that have specific roles.
6. Animal cells do not have a cell ____.
7. _______ are found in plants, and change light energy into chemical energy.
8. The _______ acts as the cell’s control center.
9. _______ is the fluid that fills the cells.
10. __________ break down food to produce energy in the cell.
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The Cell
Answers to
Student Assessments
Preliminary Test
1. cell theory
2. organelles
3. cellulose
4. nucleus
5. mitochondria
6. vacuoles
7. golgi bodies
8. chloroplast
9. chromosomes
10. endoplasmic reticulum
11. false
12. false
13. true
14. true
15. false
16. true
17. true
18. true
19. false
20. true
Video Quiz:
1. cells
2. cork
3. electron
4. other cells
5. organelles
6. wall
7. chloroplasts
8. nucleus
9. cytoplasm
10. mitochondria
Post Test
1. true
2. true
3. true
4. true
5. false
6. false
7. false
8. false
9. true
10. true
11. chloroplast
12. vacuoles
13. chromosomes
14. cell theory
15. cellulose
16. endoplasmic reticulum
17. golgi bodies
18. nucleus
19. organelles
20. mitochondria
Video Review
You Decide:
A. Hooke saw a piece of cork under his
microscope.
B. Animals do not possess a cell wall.
C. Cytoplasm is the liquid flowing
through the cell.
D. Lysosomes reuse the material in the
old tail to make new body parts for the
adult frog.
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The Cell
Answers to Student
Activities
.
The Animal Cell
Seeing Cells
1. cell membrane
2. mitochondrion
3. nucleolus
4. lysosome
5. endoplasmic reticulum
6. ribosome
7. cytoplasm
8. nuclear membrane
9. nucleus
10. vacuole
11. golgi bodies
Questions: 1. The nucleus controls the activities
of the cell.
2. The cell membrane determines which materials
enter and exit the cell.
Observations:
Part I: The cork cells are rectangular in shape.
There are no materials within the cell walls.
You can tell that the cells are not living because
they are empty.
Part II: You can see organelles in the elodea
leaf cells. Examples include chloroplasts,
vacuoles, and cytoplasm. The elodea leaf cells
are rectangular in shape and green in color due
to the presence of chlorophyll. You can tell
that the cells are living because it is possible to
identify the organelles, including moving
chloroplasts. One difference is that iodine kills
the cell, ceasing all movement. A second
difference is that by killing the cells, the iodine
makes it easier to view the organelles.
Chloroplasts are oval.
Conclusion:
Non-living cells are easier to observe because
all of the organelles have died, leaving only the
cell walls. In order to see the organelles in a
living cell, a powerful microscope is needed.
Hooke was using a very simple microscope so
it is improbable that he saw the cell as clearly
as the students were able to.
The Plant Cell
1. mitochondrion
2. vacuole
3. chloroplast
4. cytoplasm
5. endoplasmic reticulum
6. ribosome
7. nucleus
8. nucleolus
9. nuclear membrane
10. cell membrane
11. cell wall
12. golgi bodies
Vocabulary
1. cell theory, g
2. cellulose, a
3. golgi bodies, c
4. nucleus, j
5. chromosomes, h
6. cytoplasm, e
7. endoplasmic reticulum, f
8. ribosomes, b
9. mitochondria, d
10. vacuoles, i
The Cell Theory and Microscopes
Part I:
1. B
3. A
2. B
4. D
Part II:
1. F
4. F
2. T
5. T
3. T
Part III:
Student essays will vary.
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Assessment
and Student
Activity
Masters
18
The Cell
Name___________________
Preliminary Test
Directions: Fill in the blank with the correct word. A list of possible
answers is provided at the bottom of the page.
1. The _____________ states that all cells come from previously existing cells.
2. The smaller structures that make up cells are called _____________.
3. _____________ is the material that makes up the cell wall in plants.
4. The _____________ acts as the brain of the cell.
5. _____________ are the powerhouses of the cell and break down food to
produce large amounts of energy.
6. _____________ are the parts of the cell responsible for storage of food,
materials, and waste.
7. _____________ are stacks of membrane-covered sacs that package and
transport protein to the outside of the cell.
8. An organelle that enables a plant to produce its own food is called a
_____________.
9. Rod-like structures inside the nucleus that contain DNA, the chemical that acts
as a genetic blueprint, are called _____________.
10. A network of tubular passageways in the cell whose function it is to transport
materials is called the _____________.
chromosomes
cell theory
ribosomes
mitochondria
vacuoles
chloroplast
organelles
endoplasmic reticulum
nucleus
lysosomes
golgi apparatus
cellulose
19
©2001
The Cell
Name___________________
Preliminary
Test
Directions: Decide whether the answer is True (T) or False (F).
11.Robert Hooke first discovered cells by looking at a
piece of cork under an electron microscope.
T
F
12.Both plant and animal cells contain cellulose, a
strong and tough material that makes up the cell wall.
T
F
13.Plant cells contain chloroplasts, while animal cells
do not.
T
F
14.The nuclear membrane protects the nucleus by
allowing only certain materials to pass in and out.
T
F
15.Lysosomes contain RNA and direct the production of
proteins in a cell.
T
F
16.A fluid that flows through the cell and helps to carry
out the life processes of the cell is called cytoplasm.
T
F
17.Chromosomes contain DNA.
T
F
18.Electron microscopes are able to magnify objects too
small to be seen with a compound microscope.
T
F
19.Mitochondria are responsible for packaging and
transporting protein to the outside of the cell.
T
F
20. The nucleolus is located inside the nucleus of a cell.
T
F
20
©2001
The Cell
Name___________________
Video Review
Directions: During the course of the program answer the “You Decide”
questions as they are presented in the video. Answer the Video Quiz
questions at the end of the video.
You Decide:
A. What is the object Hooke saw under his
microscope?
Answer: _______________
B. Do animals possess a cell wall?
Answer: _______________
C. What is the material seen flowing through
this cell?
Answer: _______________
D. What do lysosomes do with the old tail cells?
Answer: _______________
Video Quiz:
1. All living things possess ______________?
2. Robert Hooke discovered cells while looking at a piece of ____________.
3. _______________ microscopes use magnetic fields to magnify objects.
4. All cells come from ____________ ___________.
5. ______________ are structures within cells that have specific roles.
6. Animal cells do not have a cell __________.
7. __________ are found in plants, and change light energy into chemical energy.
8. The _________________ acts as the cell’s control center.
9. ___________ is the fluid that fills the cells.
10. ______________ break down food to produce energy in the cell.
21
©2001
The Cell
Name___________________
Post Test
Directions: Decide whether the answer is True (T) or False (F).
1. Plant cells contain chloroplasts, while animal cells do
not.
T
F
2. Electron microscopes are able to magnify objects too
small to be seen with a compound microscope.
T
F
3. The nucleolus is located inside the nucleus of a cell.
T
F
4. The nuclear membrane protects the nucleus by allowing
only certain materials to pass in and out.
T
F
5. Both plant and animal cells contain cellulose, a strong
and tough material that makes up the cell wall.
T
F
6. Mitochondria are responsible for packaging and
transporting protein to the outside of the cell.
T
F
7. Robert Hooke first discovered cells by looking at a piece
of cork under an electron microscope.
T
F
8. Lysosomes contain RNA and direct the production of
proteins in a cell.
T
F
9. Chromosomes contain DNA.
T
F
10. A fluid that flows through the cell and helps to carry
T
F
22
©2001
The Cell
Name___________________
Post Test
Directions: Fill in the blank with the correct word. A list of possible
answers is provided at the bottom of the page.
11. An organelle that enables a plant to produce its own food is called a
_____________.
12. _____________are the parts of the cell responsible for storage of food,
materials, and waste.
13. Rod-like structures inside the nucleus that contain DNA, the chemical that acts
as a genetic blueprint, are called _____________.
14. The _____________ states that all cells come from previously existing cells.
15. _____________ is the material that makes up the cell wall in plants.
16. A network of tubular passageways in the cell whose function it is to transport
materials is called the _____________.
17. _____________ are stacks of membrane-covered sacs that package and
transport protein to the outside of the cell.
18. The _____________ acts as the brain of the cell.
19. The smaller structures that make up cells are called _____________.
20. _____________ are the powerhouses of the cell and break down food to
produce large amounts of energy.
lysosomes
golgi apparatus
cell theory
chloroplast
organelles
vacuoles
cellulose
chromosomes
nucleus
endoplasmic reticulum
mitochondria
ribosomes
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©2001
The Cell
Name___________________
The Animal Cell
Background: Recall from the video that the internal structures of a cell are called
organelles. In this activity you will identify the different organelles of an animal cell.
Directions: Use the vocabulary words listed below to label the parts of the animal cell.
It may help to refer to a textbook with a diagram of an animal cell to complete this
activity. Answer the questions beneath the diagram.
1.
11.
10.
9.
2.
3.
8.
7.
4.
6.
5.
vacuole
endoplasmic reticulum
cell membrane
nuclear membrane
golgi bodies
ribosome
cytoplasm
lysosome
mitochondrion
nucleus
nucleolus
Questions:
1. What is the function of the nucleus?
2. What is the role of the cell membrane?
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The Cell
Name___________________
The Plant Cell
Directions: Choose from the vocabulary words listed below to label the parts of the plant
cell. It may help to refer to a textbook with a diagram of a plant cell to complete this
activity.
12.
11.
10.
1.
2.
9.
8.
7.
3.
4.
6.
5.
vacuole
endoplasmic reticulum
cell membrane
nuclear membrane
golgi bodies
ribosome
cytoplasm
mitochondrion
25
nucleolus
chloroplast
nucleus
cell wall
©2001
The Cell
Name___________________
The Cell Theory and
Microscopes
Directions: Read the passage below about how new discoveries and improvements in technology
led to the development of the cell theory. Use this information to answer the questions on the
following page.
Cells and Microscopes
In today’s world, a great deal is known about microscopic life. We can picture microorganisms as if
they are tangible objects we can pick up and hold. Imagine if you were living in the 1600’s and all
that you know of can be seen with the unaided eye. During this time, people believed in spontaneous generation, which means that living things originate spontaneously out of material such as dust
or mud. When a few Dutch eyeglass makers invented a microscope in the late 1500’s, it was one of
the biggest breakthroughs in biology. It magnified objects up to 9 times their size. In 1674, a Dutch
scientist named Anton van Leeuwenhoek invented a simple, hand held microscope. He examined
living cells in substances like pond water and blood. He observed things that no one had ever seen
before. His microscope magnified objects up to 270 times their size!
As new microscopes were invented, new hypotheses about cells were developed. A hypothesis is a
scientific prediction that can be tested. In 1665, the English scientist Robert Hooke used a
microscope to observe thin slices of cork. He noticed spaces separated by walls and referred to
these spaces as cells, meaning “little rooms.”
A German botanist named Matthias Schleiden made the next discovery concerning cells. In 1838,
he reported that all plants are made of cells. The following year, German zoologist, Theodor Schwann,
concluded that animals are also made of cells. Two decades later, Rudolf Virchow, a pathologist,
inferred that all cells come from preexisting cells. These new pieces of evidence developed into a
more accepted observation in science called the cell theory. The cell theory consists of the
following three principles:
1) cells are the basic units of life;
2) all organisms are made of one or more cells; and
3) all cells arise from existing cells.
A new principle has been added to the cell theory in its modern form. Part four of the cell theory
states that cells contain the hereditary information of the organisms of which they are a part, and this
information is passed from parent cell to daughter cell. This addition to the cell theory was due, in
part, to the development of more powerful microscopes
Today we commonly use compound light microscopes. Compound light microscopes use lenses to
bend beams of light and can magnify objects up to 2000 times their size. In 1931, a man named
Ernest Rusk built the first electron microscope. The electron microscope uses a magnetic field to
bend beams of electrons and can magnify objects up to 1,000,000 times their size. The latest
technology available in microscopy is called a scanning interferometric apertureless microscope.
This microscope uses the principles of a light microscope, but has the potential to allow imaging of
single atoms! Science and technology have come a long way since the 1600’s.
26
©2001
The Cell
Name___________________
The Cell Theory and
Microscopes (cont.)
Directions: Part I: Circle the correct multiple choice answer. Part II: Decide whether the
statement is True (T) or False (F).
Part I
1. Which microscope represents the most recent development?
A. simple microscope
B. scanning interferometric apertureless microscope
C. compound light microscope
D. electron microscope
2. The first microscope was invented in the:
A. late 1600’s
C. early 1600’s
B. late 1500’s
D. early 1500’s
3. Rudolph Virchow was a:
A. pathologist
B. German zoologist
C. German botanist
D. English scientist
4. Spontaneous generation means:
A. hereditary information is passed from a parent cell to a daughter cell
B. all cells arise from existing cells
C. life comes only from other life
D. living things can originate from anything
Part II
1. Electron microscopes can only magnify objects up to 1000 times their
size.
2. The modern cell theory has four principles.
3. Robert Hooke was the first person to use the term “cell.”
4. A theory is a scientific fact.
5. The latest technology in microscopy allows imaging of particles
as small as atoms.
T
T
T
T
T
F
F
F
F
F
Part III – Think about how far science has come since the 1600’s. Write a short essay about
what you think new developments in technology could mean for the cell theory. Presently,
a microscope is available that enables us to view the smallest unit of matter known to
humans, the atom. Do you think there are organisms smaller than the atom that we still do
not have the technology to see? What would be possible implications of such a discovery?
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©2001
The Cell
Name___________________
Seeing Cells
Background: The English scientist Robert Hooke discovered the cell by examining a
piece of cork under a microscope. In this lab, you will observe what Robert Hooke
discovered and compare it to the cell of a living organism.
Objective: In this activity you will use a microscope to locate structures in a cell, compare
living and non-living cells, and describe the shapes of cells.
Materials:
microscope
slides
cover slip
razor blade
medicine dropper
forceps
water
large cork stopper
elodea leaf
iodine staining solution
Procedure:
Part I:Cork
1. Your teacher will prepare a slice of cork thin enough for microscopic examination.
2. Place the cork slice in a small drop of water on a slide. Using your medicine dropper,
add a drop of water to the top of the cork slice and cover it with a cover slip.
3. Observe the cork under low power and draw what you see below:
4. Observe the cork under high power. Draw what you see below, paying attention to the
shapes of the cells. Label the cell wall.
Observations:
1. What is the general shape of the cork cells?
2. Does there appear to be any materials within the cell walls?
3. How can you tell that the cells in cork are non-living cells?
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©2001
The Cell
Name___________________
Seeing Cells (cont.)
Part II: Elodea Leaf
1. Using your forceps, place your leaf in a drop of water on a slide and add a cover slip.
2. Examine the leaf under low power and note the shape of the cells. Find a section of the
leaf where the cells appear most clearly.
3. Center the clearest part of the leaf. While under high power, use the fine adjustment to
focus the microscope.
4. Look for small moving bodies. Note the direction in which they are moving.
5. Make a new wet mount by placing a different elodea leaf in a drop of the iodine staining
solution and covering it with a cover slip.
6. Observe the leaf under high power. Draw what you observe in the space provided:
Observations:
What structures do you see in the elodea leaf cells that you did not see in the cork cells?
What is the general shape and color of the elodea leaf cells?
In the slide prepared with water, how can you tell that the elodea leaf cells are living?
What are two main differences between the slide of the elodea leaf that was prepared using
water and the slide of the elodea leaf that was prepared using the iodine staining solution?
1)
2)
What is the general shape of the chloroplasts?
Conclusion: Was it easier to observe living cells or non-living cells? Think about the type
of microscope you used. Do you think Robert Hooke saw the very same thing you saw in
this lab? Explain the reasons for your answers.
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©2001
The Cell
Name___________________
Vocabulary of The Cell
Directions: Unscramble the following vocabulary words and match each
word with its correct definition.
___ 1. lcel rhotye
___ 2. slceuleol
a. a strong and tough material that makes up
a cell wall
b. round structures that contain a chemical
called RNA, sometimes attached to the
endoplasmic reticulum
___ 3. ioglg edbiso
___ 4. lsunceu
___ 5. seomcmshroo
c. membrane-covered sacs that package and
transport protein to the outside of the cell
d. rod-shaped structures that supply most of
the energy for the cell, sometimes referred
to as the powerhouse of the cell
___ 6. tmsaoyclp
___ 7. sadocielnmp urtmlueci
___ 8. oseriboms
e. fluid that flows through the cell,
containing a large amount of water, as
well as many chemicals and structures
f. network of tubular passageways that
transports materials throughout the cell
___ 9. ratmohnidoci
___ 10. sovaluce
g. all living things are made of cells; cells
are the basic units of structure and
function in an organism; and all cells come
from previously existing cells
h. found inside the nucleus, these dark,
rod-like structures contain proteins and
DNA
i. parts of the cell where materials are
stored
j. sometimes referred to as the cell’s brain, it
regulates all cellular activities
30
©2001