Cells - ed Online

Visual Learning Companywww.visuallearningco.com

25 Union StreetBrandon VT 05733

1-800-453-8481

Teacher's Guide

Cells

Editors:Brian A. Jerome, Ph.D.Stephanie Zak Jerome

Assistant Editors:Anneliese BrownLouise Marrier

Graphics:Lyndsey Canfield

Dean LadagoFred Thodal

1-800-453-8481Visual Learning CompanyCells

The purchase of this video program entitles the user the right to reproduce or duplicate, in whole or in part, this teacher’s guide and the black line master handouts for the purpose of teaching in conjunction with this video, Cells. The right is restricted only for use with this video program. Any reproduction or duplication, in whole or in part, of this guide and student masters for any purpose other than for use with this video program is prohibited.

The video and accompanying teacher’s guide are for instructional use only. In showing these programs, no admission charges are to be incurred. The programs are to be utilized in face-to-face classroom instructional settings, library settings, or similar instructional settings.

Duplication Rights are available, but must be negotiated with the Visual Learning Company.

Television, cable, or satellite rights are also available, but must be negotiated with the Visual Learning Company.

Closed circuit rights are available, and are defi ned as the use of the program beyond a single classroom but within a single campus. Institutions wishing to utilize the program in multiple campuses must purchase the multiple campus version of the program, available at a slightly higher fee.

Video streaming rights are available and must be negotiated with the Visual Learning Company.

Discounts may be granted to institutions interested in purchasing programs in large quantities. These discounts may be negotiated with the Visual Learning Company.

The video and this teacher’s guide are the exclusive property of the copyright holder. Copying, transmitting, or reproducing in any form, or by any means, without prior written permission from the copyright holder is prohibited (Title 17, U.S. Code Sections 501 and 506).

Copyright © 2008

ISBN 9781592342198

A Message from our Company . . .Visual Learning is a Vermont-based, family-owned company specializing in the creation of science programs. As former classroom science teachers we have designed our programs to meet the needs and interests of both students and teachers. Our mission is to help educators and students meet educational goals while experiencing the thrill of science!

Viewing Clearances

Use and Copyright:

1-800-453-8481Visual Learning Company Cells

Table of Contents2

2

2

4

5

6

7

7

8

12

13

14

16

18

19

20

21

23

24

25

A Message from our Company

Viewing Clearances

Use and Copyright

National Standards Correlations

Student Learning Objectives

Assessment

Introducing the Program

Program Viewing Suggestions

Video Script

Answer Key to Student Assessments

Answer Key to Student Activities

Pre-Test

Post-Test

Video Review

Vocabulary

Writing Activity

Developing the Cell Theory

Make Your Own Cell

Making Pizza: Cells at Work!

The Amazing Amoeba


National Standards CorrelationsBenchmarks for Science Literacy(Project 2061 - AAAS)

National Science Education Standards(Content Standards: K-4, National Academy of Sciences)

Grades 3-5

The Living Environment - Cells (5C)

By the end of the 5th grade, students should know that:

• Microscopes make it possible to see that living things are made mostly of cells. Some organisms are made of a collection of similar cells that benefi t from cooperating.

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.

• 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.

Structure and Function in Living Systems

Life Science - Content Standard C

As a result of their activities in grades 5-8, all students should develop an understanding of:


Student Learning ObjectivesUpon viewing the video and completing the enclosed student activities, students will be able to do the following:

• Understand that cells are the basic building blocks of life.

• Explain the main components of the cell theory:- all organisms are made up of one or more cells.- the cell is the basic unit of life in all living things.- all cells come from previously existing cells.

• Appreciate the fact that cells are very tiny organisms, too small to be seen with the naked eye.

• Identify and describe the function of the following parts of a cell:- cell membranecytoplasm- nucleus

• Understand that when new cells are made, they receive a copy of the genetic material (DNA) from the original cell.

• Generally describe prokaryotic cells (bacteria) as cells that do not possess a nucleus.

• Explain that there is a wide variety of prokaryotic cells. Some bacteria cause disease and infection, but not all are harmful.

• Explain that plants and animals are made up of eukaryotic cells, which tend to have a greater number of cell parts.

• Understand that a third group of cells, archaea, have some characteristics common to prokaryotic and eukaryotic cells.

• Differentiate between plant and animal cells by explaining that plant cells possess cell walls and chloroplasts, while animal cells do not.

• Explain the important role chloroplasts play in the process of photosynthesis.

• List some of the important activities carried out by cells, including the conversion of food into energy, the exchange of materials between the cell and the outside environment, and cell reproduction.


The Post-Test can be utilized as an assessment tool following student completion of the program and student activities. The results of the Post-Test can be compared against the results of the Preliminary Test to assess student progress.

The Preliminary Test is an assessment tool designed to gain an understanding of students’ 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.

Assessment

Preliminary Test (p. 14-15):

Video Review (p. 18):

Post-Test (p. 16-17):

The Video Review can be used as an assessment tool or as a student activity. There are two sections. The fi rst part contains questions displayed during the program. The second part consists of a fi ve-question video quiz to be answered at the end of the video.


Introducing the Program

Program Viewing SuggestionsThe student master “Video Review” (p. 18) is provided for distribution to students. You may choose to have your students complete this master while viewing the program or do so upon its conclusion.

The program is approximately 14 minutes in length and includes a fi ve-question video quiz. Answers are not provided to the Video Quiz in the video, but are included in this guide on page 12. You may choose 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.

Before showing the video program, ask students if they have eaten bread or yogurt today. Tell them that living cells are used to make these foods. Have them look at their hand. Explain to students that the skin on the back of their hand is made up of millions of cells. The human body is made up of billions and billions of living cells.

Write the following phrase on the board: “Cells are the building blocks of life”. Ask students for their interpretation of this phrase. As a class, discuss why cells are so important to all living things, including humans. Cells possess many structures and processes, enabling them to carry out a wide variety of important functions. Tell students to pay close attention to the video to learn more about cell structures and processess.


Video Script 1. What important thing do living organisms have in common? 2. Here are some clues. 3. This thing is so small it can’t be seen with the naked eye. 4. In fact, there are billions of these things in the human body. 5. These things are found in all plants and animals,... 6. ...including trees,... 7. ...fi sh,… 8. ...and birds. 9. These structures are sometimes referred to as the building blocks of life.10. What are these incredibly important things on which life depends? 11. They are cells.12. What exactly are cells?13. What jobs do cells carry out…14. ...and why are they so important?15. During the next few minutes, we are going to try to answer those questions...16. ...as we explore the fascinating features of cells.17. Graphic Transition – Development of the Cell Theory18. In 1665, a British scientist named Robert Hooke....19. ...used a simple microscope to look at a thin slice of cork.20. He saw something that looked like this. 21. You Observe! Describe what Hooke saw. 22. Hooke saw hundreds of tiny little boxes, which he called cells. What he was actually

seeing was the remaining walls of once-living plant cells.23. Later, a Dutch scientist named Antonie van Leeuwenhoek used a simple microscope

to identify tiny animals in pond water...24. ...and blood cells in different animals.25. He was also the fi rst person to see bacteria.26. And, he discovered that yeast, used to make bread dough rise,...27. ...is actually a single-celled organism.28. Following the discoveries of Hooke and van Leeuwenhoek, it took scientists over 150

years to realize that all living things are made of cells.29. In the late 1830s, a German scientist named Theodor Schwann concluded that all

plants and animals are made of cells.30. Schwann developed the fi rst two parts of what is now called the cell theory.31. The fi rst part states that all organisms are made up of one or more cells.32. So all living things, from very small organisms to animals as large as elephants, are

made up of cells.33. The second part of the cell theory states that the cell is the basic unit of life in all living

things.34. This means that no life can exist without cells.


Video Script35. About 20 years later, a German doctor, Rudolf Virchow, concluded ...36. ...that cells only develop from other cells.37. This third idea was added to the cell theory, stating that all cells come from previously

existing cells.38. So, in other words, cells can’t just magically appear, they have to come from other

cells as they divide.39. Together, these three very important concepts make up the cell theory.40. Graphic Transition – Common Cell Parts41. You Decide! Look at your hand. Can you see skin cells?42. No, you can’t see the cells because they are very small.43. Generally speaking, cells are so small that most cannot be seen with the naked eye.44. For example, cells are so small it is estimated that over 100 trillion cells make up the

human body.45. All cells have a cell membrane, which is a thin, sheet-like structure that surrounds the

cell.46. The cell membrane holds the cell together.47. It separates material inside the cell from material outside.48. The cell membrane also controls the movement of material in and out of the cell.49. Inside the cell is a fl uid called cytoplasm.50. Cytoplasm is a jelly-like mixture of water and other chemicals.51. The cytoplasm surrounds structures in the cell, which are collectively referred to as

organelles.52. Many cells contain a very important organelle – the nucleus.53. You can think of the nucleus as the control center of the cell, responsible for

coordinating the activities of the cell.54. The nucleus also contains genetic material, called DNA.55. When new cells are made, they receive a copy of the genetic material from the

original cell.56. Genetic material is very important because it contains the blue print for the cell, which

determines how a cell looks, develops, and functions.57. Graphic Transition – Types of Cells58. There are hundreds of different types of cells, which scientists commonly divide into

several major groups.59. Prokaryotic cells are cells that do not have a nucleus.60. Prokaryotic cells are also called bacteria.61. Generally speaking, bacteria cells are smaller than other types of cells. 62. There are thousands of different types of bacteria cells.63. Some cause disease and infection.64. But most bacteria are not harmful. Some are even used in making foods, such as

yogurt and cheese.


Video Script65. Another main group of cells, eukaryotic cells, do have a nucleus.66. Eukaryotic cells also have a greater number of cell parts.67. Plants and animals are made up of eukaryotic cells.68. A third group of cells, archaea, have some characteristics common to both prokaryotic

and eukaryotic cells. 69. Many but not all archaea live in extreme environments such as the hot geothermal

springs and these salt pools in Death Valley.70. Graphic Transition – Plant and Animal Cells71. These giant redwood trees in Northern California are among the largest living things

on the planet.72. Some of these trees are over 300 feet, or 100 meters, tall!73. One of the key factors enabling them to reach such great heights is found in their

tiniest structures – their plant cells.74. Plant cells are surrounded by a relatively rigid cell wall.75. Cell walls are made of cellulose. That’s a strong material that enables plants,

including trees, to grow tall.76. Animal cells do not have a cell wall – only a cell membrane.77. Plant cells also differ from animal cells in that they contain organelles called

chloroplasts. These enable them to make their own food from the sun’s light energy.78. You Decide! What is the process by which plants make food from the sun’s light

energy?79. Photosynthesis is the process by which plants convert light energy from the sun into

food.80. Unlike plants, animals can’t produce their own food and must eat other living things,

such as grass, fruits, vegetables, and meat, to obtain energy.81. Graphic Transition – Activities of Cells82. There are many, many important functions carried out by cells. But we only have time

to mention a few.83. One important job that cells perform involves converting food into energy that a cell

can use to grow and repair itself.84. Several specialized organelles are involved in what is known as energy conversion.85. Cells are also capable of exchanging materials inside the cell with those on the

outside.86. The cell membrane and other organelles help regulate the exchange of food, water,

gases, and many other materials.87. Cells create other new cells in the process of reproduction.88. Reproduction commonly occurs through cell division, during which a single cell

divides into two new cells.89. Each new cell has the same general characteristics of the original cell.


Video Script 90. Graphic Transition – Summing Up 91. During the past few minutes, we have explored some of the fascinating

characteristics of cells. 92. We began by discussing the cell theory, including the important discoveries that led

to its formation. 93. We explored common cell parts, including the cell membrane and nucleus. 94. We highlighted the difference between prokaryotic and eukaryotic cells. 95. We also focused on the differences between plant and animal cells. 96. Finally, we discussed activities of cells, including energy conversion and

reproduction. 97. So, the next time you look at yourself in the mirror,… 98. …admire beautiful fl owers,… 99. …or pet an animal,…100. …think about some of the things we have discussed during the past few minutes. 101. You just might think about living organisms and cells a little differently. 102. Graphic Transition – Video AssessmentFill in the correct word to complete the sentence. Good luck and let’s get started.1. The ____ is the basic unit of life.2. The _____ is the control center of the cell.3. _____ cells do not contain a nucleus.4. Plant cells are surrounded by a rigid cell ___.5. New cells are produced in the process of ______.5. New cells are produced in the process of ______.


Answer Key to Student AssessmentsPre-Test (p. 14-15) Post-Test (p. 16-17)

Video Review (p. 18)

1. b - cells 2. d - life 3. a - smaller 4. c - cell membrane 5. d - cytoplasm 6. b - nucleus 7. b - eukaryotic cells 8. a - photosynthesis 9. c - cell wall and chloroplasts10. d - reproduction11. true12. false13. false14. true15. false16. All organisms are made up of one or more cells. The cell is the basic unit of life in all living things. All cells come from previously existing cells.17. Cells can’t be seen with the naked eye because they are very small. It is estimated that over 100 trillion cells make up the human body.18. The cell membrane is a thin, sheet-like structure that surrounds the cell and holds the cell together. The cell membrane separates material inside the cell from material outside it. The cell membrane also controls the movement of material in and out of the cell.19. Prokaryotic cells are cells that do not have a nucleus.20. Plant cells contain chloroplasts, which enable them to carry out photosynthesis.

1. c - cell wall and chloroplasts 2. b - eukaryotic cells 3. d - cytoplasm 4. a - smaller 5. b - cells 6. d - reproduction 7. a - photosynthesis 8. b - nucleus 9. c - cell membrane10. d - life11. false12. false13. true14. false15. true16. Plant cells contain chloroplasts, which enable them to carry out photosynthesis.17. The cell membrane is a thin, sheet-like structure that surrounds the cell and holds the cell together. The cell membrane separates material inside the cell from material outside it. The cell membrane also controls the movement of material in and out of the cell.18. Prokaryotic cells are cells that do not have a nucleus.19. Cells can’t be seen with the naked eye because they are very small. It is estimated that over 100 trillion cells make up the human body.20. All organisms are made up of one or more cells. The cell is the basic unit of life in all living things. All cells come from previously existing cells.

1. Hooke saw hundreds of tiny little boxes, which he called cells. He was actually seeing the remaining walls of once-living plant cells.2. No, you can’t see the skin cells on your hand because they are very small.3. Photosynthesis is the process by which plants convert light energy from the sun into food.

1. The cell is the basic unit of life.cell is the basic unit of life.cell2. The nucleus is the control center of the cell.3. Prokaryotic cells do not contain a nucleus.4. Plant cells are surrounded by a rigid cell wall.5. New cells are produced in the process of reproduction.


Writing Activity (p. 20)

Vocabulary (p. 19 )Answer Key to Student Activities1. cells2. cell theory3. cell membrane4. cytoplasm5. nucleus6. prokaryotic cells7. eukaryotic cells8. chloroplasts9. photosynthesis10. cell division

In 1665, the British scientist, Robert Hooke, used a simple microscope to look at a thin slice of cork. He saw box-like structures called cells. Over the years, scientists made other discoveries that led to the development of the cell theory. This theorystates: all organisms are made of cells; cells are the basic unit of life in living things; and cells come from previously existing cells. Most cells are so small they cannot be seen with the naked eye. All cells have a cell membrane, which is a thin, sheet-like structure that surrounds the cell. Inside the cell is a fl uid called cytoplasm. Many cells contain an important structure called the nucleus, which is responsible for controlling cell activities. It contains genetic material, also called DNA. There are several major groups of cells. Prokaryotic cells, also called bacteria, do not have a nucleus. Eukaryotic cells do have a nucleus and make up plants and animals. A third group of cells called archaea often live in extreme environments, such as in salt or geothermal pools.

In Your Own Words (p. 20)1. The cell theory states: all organisms are made up of one or more cells; the cell is the basic unit of life in living things; all cells come from previously existing cells.2. A prokaryotic cell does not have a nucleus. A eukaryotic cell does have a nucleus and has a greater number of cell parts.3. Plant cells are surrounded by a cell wall and a cell membrane. An animal cell is surrounded by just a cell membrane. Plant cells contain organelles called chloroplasts. Animal cells do not.

Developing the Cell Theory (p. 21-22)1. B - late 1500s2. B - cork3. D - life4. B - previously existing cells5. A - compound microscope1. true2. false3. true4. true

5. false

Make Your Own Cell (p. 23)

Making Pizza: Cells at Work! (p. 24)

The Amazing Amoeba (p. 25)1. nucleus2. cell membrane3. pseudopod4. food vacuole5. cytoplasm

1. Cytoplasm is a jelly-like mixture of water and other chemicals which surrounds the organelles in the cell. The nucleus is the control center of the cell and is responsible for coordinating the activities of the cell. The cell membrane is a thin, sheet-like structure that surrounds the cell. The cell membrane holds the cell together. It also controls the movement of material in and out of the cell.2. The plant cell has structures called chloroplasts which are represented by the green jelly bean in the model. Chloroplasts carry out the process of photosynthesis. A plant cell also has a cell wall which surrounds the cell membrane. Animal cells do not have these structures.3. The cell membrane in the model is represented by the ziploc bag. The bag can’t control the movement of material in and out of the cell like the actual cell membrane. The actual cell membrane would be thinner than the bag.

1. Yeasts are eukaryotic microorganisms that have been used for thousands of years in baking breads.2. The yeast seemed to “expand” after sitting in the water and sugar mixture. The yeast cells were converting the sugar into energy and releasing carbon dioxide.3. The carbon dioxide gas released from the yeast cells formed pockets or bubbles, causing the bread to “rise.”

Pre-Test

4. The thin, sheet-like structure that surrounds the cell is called the:

5. Inside the cell is a jelly-like fl uid called:

1. All organisms are made up of one or more of the following:

2. In all living things, cells are referred to as the basic unit of:

3. Compared to the size of the head of a pin, most cells are much:

Circle the best answer for each of the following questions.

6. Prokaryotic cells do not have the following structure:

10. Cells create new cells in the following process:

7. These types of cells have a nucleus and are found in plants and animals:

8. Plant cells are able to convert the sun’s light energy into food in the following process:

9. Animal cells do not have the following structures:

a. viruses b. cells c. paramecium d. cell walls

a. diffusion b. reproduction c. fermentation d. life

a. smaller smaller smaller b. heavier c. larger larger larger d. more voluminous

a. cell water cell water cell water b. enzymatic fl uid c.enzymatic fl uid c.enzymatic fl uid cell jello d. cytoplasm

a. cytoplasm b. nucleus c. cell d. vacuole membrane

a. cytoplasm b. nucleus c. cell d. hereditary membrane material

a. prokaryotic b. eukaryotic c. archaea d. bacteria cellscellscell cells

a. photosynthesis b. respiration c. fermentation d. glycolysis

a. food vacuoles b. nucleus c. cell wall and d. mitochondria chloroplasts

a. photosynthesis b. respiration c. transpiration d. reproduction

Visual Learning Company

Page

14Cells

Name

Write a short answer for each of the following.

Pre-Test

16. List two of the three parts of the cell theory.

17. Why can’t cells be seen with the naked eye?

18. What is the cell membrane and what is its job?

11.

12.

13.

14.

15.

Write true or false next to each statement.

19. What are prokaryotic cells?

20. What cell part enables plant cells to carry out photosynthesis?

In 1665, a British scientist named Robert Hooke used a simple microscope to look at a thin slice of cork.

The cell theory states that cells are rarely found in living things.

Most cells can be seen with the naked eye.

The cell nucleus contains genetic material, also called DNA.

Animal cells contain cell walls and chloroplasts.


Page

15Cells

Name

Circle the best answer for each of the following questions.

Post-Test

1. Animal cells do not have the following structures:

a. food vacuoles b. nucleus c. cell wall and d. mitochondria chloroplasts

2. These types of cells have a nucleus and are found in plants and animals:

a. prokaryotic b. eukaryotic c. archaea d. bacteria cellscellscell cells

3. Inside the cell is a jelly-like fl uid called:

a. cell water cell water cell water b. enzymatic fl uid c.enzymatic fl uid c.enzymatic fl uid cell jello d. cytoplasm

4. Compared to the size of the head of a pin, most cells are much:

a. smaller smaller smaller b. heavier heavier heavier c. larger larger larger d. more voluminous

5. All organisms are made up of one or more of the following:

a. viruses b. cells c. paramecium d. cell walls

6. Cells create new cells in the following process:

a. photosynthesis b. respiration c. transpiration d. reproduction

7. Plant cells are able to convert the sun’s light energy into food in the following process:

a. photosynthesis b. respiration c. fermentation d. glycolysis

8. Prokaryotic cells do not have the following structure:

a. cytoplasm b. nucleus c. cell d. hereditary membrane material

9. The thin, sheet-like structure that surrounds the cell is called the:

a. cytoplasm b. nucleus c. cell d. vacuole membrane

10. In all living things, cells are referred to as the basic unit of:

a. diffusion b. reproduction c. fermentation d. life


Page

16Cells

Name

Post-Test

Write a short answer for each of the following.

16. What cell part enables plant cells to carry out photosynthesis?

17. What is the cell membrane and what is its job?

18. What are prokaryotic cells?

11.

12.

13.

14.

15.

Write true or false next to each statement.

19. Why can’t cells be seen with the naked eye?

20. List two of the three parts of the cell theory.

Most cells can be seen with the naked eye.

Animal cells contain cell walls and chloroplasts.

In 1665, a British scientist named Robert Hooke used a simple microscope to look at a thin slice of cork.

The cell theory states that cells are rarely found in living things.

The cell nucleus contains genetic material, also called DNA.


Page

17Cells

Name

After you watch the video, test your knowledge with these questions.

While you watch the video, answer these questions:

3. You Decide!

Video Review

2. You Decide!

1. You Observe!Describe what Hooke saw.

Look at your hand. Can you see skin cells?

What is the process by which plants make food from the sun’s light energy?

1. The ______________ is the basic unit of life.

2. The ______________ is the control center of the cell.

3. __________________ cells do not contain a nucleus.

4. Plant cells are surrounded by a rigid cell __________.

5. New cells are produced in the process of ____________________.


Page

18Cells

Name

VocabularyUse these words to fi ll in the blanks next to the sentences below.

1.

7.

2.

6.

8.

4.

5.

3.

9.

10.

Wo

rds

Basic building blocks of life.

A theory that states: all organisms are made of cells, the cell is the basic unit of life in living things, and cells come from previously existing cells.

Thin, sheet-like structure that surrounds a cell.

Jelly-like mixture of water and other materials in cell.

Control center of a cell; contains genetic material (also called DNA).

Cells that do not have a nucleus; also called bacteria.

Cells that possess a nucleus; plants and animals are made of these cells.

Structures in plant cells that carry out the process of photosynthesis.

Process by which plant cells convert the sun’s energy into food.

Common process by which cells reproduce.

cells

cell theory

cell membrane cytoplasm

photosynthesis nucleusprokaryotic cells eukaryotic cells

chloroplastscell division


Page

19Cells

Name

2. What is the difference between a prokaryotic cell and a eukaryotic cell?

1. State the three parts of the cell theory.

Use the correct word from above to complete the sentences in the following paragraph.

Writing Activity

In Your Own Words

3. List two differences between a plant cell and an animal cell.

Wo

rds

In 1665, the British scientist, Robert Hooke, used a simple ___________ to look at a thin slice of cork. He saw box-like structures called __________. Over the years, scientists made other discoveries that led to the development of the ___________________. This theory states: all organisms are made of cells; cells are the basic unit of life in living things; and cells come from previously existing cells. Most cells are so small they cannot be seen with the naked eye. All cells have a cell _________________, which is a thin, sheet-like structure that surrounds the cell. Inside the cell is a fl uid called __________________. Many cells contain an important structure called the _____________, which is responsible for controlling cell activities. It contains genetic material, also called _________. There are several major groups of cells. _______________ cells, also called bacteria, do not have a nucleus. _________________ cells do have a nucleus and make up plants and animals. A third group of cells called ___________often live in extreme environments, such as in salt or geothermal pools.

cells

cell theorymicroscope

membranecytoplasm

nucleus DNA

prokaryotic

eukaryotic

archaea


Page

20Cells

Name

Developing the Cell Theory

Background: Imagine living in the 1600s and all that you knew about could only be seen with the naked eye. People did not know there were thousands of different kinds of tiny life forms too small to be seen with the unaided eye. When a few Dutch eyeglass

Later, a German botanist named Matthias Schleiden made the next major 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 stated that all cells come from preexisting cells. Together, these pieces of evidence developed into an important observation in science called the cell theory. The cell theory consists of the following three parts: 1. cells are the basic units of life 2. all organisms are made of one or more cells 3. all cells come from existing cells.

More recently a fourth part has been added to the cell theory. Part four of the cell theory states that cells contain the hereditary information that 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. There may be a compound light microscope in your classroom. 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 fi rst electron microscope. The electron microscope uses a magnetic fi eld to bend beams of electrons and can magnify objects up to 1,000,000 times their size. Science and technology have come a long way since the 1600’s!

Directions: Read the information below and answer the questions on the next page.

makers invented a microscope in the late 1500s, it was one of the biggest breakthroughs in science. Early microscopes magnifi ed objects up to nine times their size. As more powerful microscopes were invented, new ideas about cells were developed. 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.” In 1674, a Dutch scientist named Anton van Leeuwanhoek invented a better and simpler hand-held microscope. His microscope magnifi ed objects up to 270 times their size! He looked at living cells in pond water and blood cells. He saw things that no one had ever seen before.


Page

21Cells

Name

Developing the Cell TheoryDirections: Circle the correct multiple choice answer.

1. This fi rst microscope was invented in the:A. late 1600s C. early 1600sB. late 1500s D. early 1500s

2. Robert Hooke used a simple microscope to observe a thin slice of:A. blood cells C. fern leafB. cork D. plastic

3. Cells are the basic unit of:A. plastic C. metalB. air B. air B. air D. life

4. All cells come from: A. thin air A. thin air A. thin air C. bacterial cellsB. previously existing cells D. the oceans

5. The following type of common microscope use lenses to bend a beam of light:

A. compound microscope C. scanning acoustic microscopeB. electron microscope D. scanning electron microscope

Directions: Decide whether the statement is True (T) or False (F)

1. The modern cell theory has four principles.

2. Electron microscopes can only magnify objects up to 100 times their size.

3. Robert Hooke was the fi rst scientist to use the term “cell,” meaning “little rooms.”

4. All organisms are made up of one or more cells.

5. There is only one type of microscope used today.

T F

T F

T F

T F

T F

Think about how far science has come since the 1600s. Write a short essay about what you think new developments in technology could mean for the cell theory. Presently, microscopes are available that enable 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 some possible implications of such a discovery?


Page

22Cells

Name

Make Your Own Cell

Questions:

You can’t see cells because they are very small. Generally speaking, cells are so small that most cannot be seen with the naked eye. For example, it is estimated that over 100 trillion cells make up the human body. All cells have a cell membrane, which is a thin sheet-like structure that surrounds the cell. The cell membrane holds the cell together. It separates material inside the cell from material outside. The cell membrane also controls the movement of material in and out of the cell. Inside the cell is a fl uid called cytoplasm. Cytoplasm is a jelly-like mixture of water and other chemicals. The cytoplasm surrounds the structures in the cell that are collectively referred to as organelles. Many cells contain a very important organelle - the nucleus. You can think of the nucleus as the control center of the cell, responsible for coordinating the activities of the cell. The nucleus also contains genetic material called DNA. When new cells are made, they receive a copy of the genetic material from the original cell. Genetic material is very important because it contains the blueprint for the cell. This determines how a cell looks, develops, and functions.

Plant cells are different from animal cells. For example, plants have structures called chloroplasts, which enable them to convert energy from the sun into food. They also have a cell wall that surrounds the cell membrane. The cell wall contains cellulose, which helps plants stand erect. There are many other organelles in plant and animal cells. But for now you will work with the ones we have just mentioned. In this activity you will make a model of your own plant or animal cell.

Materials: ziploc bag, different colored jelly beans (including green), small paper bag or tissue paper, clear thin gelatin mix, diagrams of plant and animal cells.

Directions:

1. Work with a partner in this activity. One person will make a plant cell and the other person will make an animal cell.2. First make an animal cell. Obtain a ziploc bag.3. Your teacher will provide you with some of the gelatin mixture. Fill the ziploc bag half full of gelatin. The gelatin mix represents cytoplasm.4. Next, add a jelly bean to represent the nucleus. 5. Now work with your partner to make a plant cell. Repeat steps 3 and 4.6. Also add a green jelly bean to represent a chloroplast.7. Using thin paper or a paper bag, cover the ziploc bag. This represents the cell wall.

1. Describe some of the structures in your cells.2. How is your plant cell different from your animal cell?3. How is the cell membrane in your cell model different from an actual cell membrane?


Page

23Cells

Name

Making Pizza: Cells at Work!Background: If you have ever made bread, you have used a very important living organism in the recipe. What is this small living organism? The answer is yeast. Yeasts are eukaryotic microorganisms that have been used for thousands of years in baking breads. Yeast cells convert sugar into energy and release carbon dioxide. Yeast is used to make bread. Carbon dioxide gases released from yeast cells form pockets or bubbles, causing the bread to “rise.” This makes it lighter. You can buy yeast in small packets in the grocery store. When mixed with warm water and a little sugar, yeast cells become active. In this activity you will work with yeast to make pizza dough.

Materials:1 cup warm water1 envelope yeast1 tsp sugar1 tsp salt2 tbsp oil2 1/2 cups fl our

Directions:

This recipe makes two thin pizza crusts. If you would prefer thicker crust, double the recipe.

1. Pour warm water into mixing bowl and add one teaspoon of sugar. Be careful! If the water is too hot, it will kill the yeast. 2. Sprinkle yeast onto the water and gently stir. Allow to sit for fi ve minutes. If you have a microscope in your classroom, place a drop of the yeast mixture on a slide and view it under the microscope.3. Add salt and oil. Mix together.4. Add the fl our and mix.5. Cover the mixture with a clean cloth and let it sit for 15 minutes. Observe how the dough rises.6. Divide the dough in half and place on a lightly-fl oured surface. Roll it to the desired size.7. Place the dough on a pan.8. Add toppings.9. Bake in a 425 degree oven for 20 minutes. For best results, bake for ten minutes, take it out of oven, add cheese, and bake for another ten minutes.

1. What is yeast?2. What did you observe after fi ve minutes of the yeast sitting in the water and sugar mixture. What was occurring?3. Why did the dough “rise” after 15 minutes?

Questions:


Page

24Cells

Name

The Amazing AmoebaBackground: Amoebas are single-celled organisms classifi ed in the group protozoa. Amoeba live in freshwater, saltwater, wet soil, and even inside animals. They cannot produce their own food. They are heterotrophs and need to eat other living things. Amoebas do not have a defi nite body shape. They have “false feet” called pseudopods, which consist of lobes of cytoplasm. These enable the organism to move, engulf food, and change shape.

Directions: Use the descriptions below to identify the structures of the amoeba.

Cytoplasm: fl uid-like mixture containing organellesFood vacuole: surrounds, engulfs, and digests food inside the cellPseudopod: extension of the body that propels the protistCell membrane: thin, sheet-like structure that surrounds the cellNucleus: control center of the cell; contains hereditary material

food source1. 2.

3.

4.5.


Page

25Cells

Name

Cells - ed Online

Documents

Transcript of Cells - ed Online