A JOURNEY THROUGH THE CELL
PART TWO—
CELL FUNCTIONS:
A CLOSER LOOK
Teacher’s Guide
INTRODUCTION
This Teacher’s Guide provides information to help you get the most out of A Journey Through
the Cell: Part Two—Cell Functions: A Closer Look. The contents in this guide will allow you to
prepare your students before using the program and present follow-up activities to reinforce the
program’s key learning points.
This program examines three main activities of the cell: energy storage and release, protein synthesis, and cell reproduction. Students take a closer look at important organelles such as mitochondria and chloroplasts, and the roles they play in cell metabolism. Also examined are proteins,
amino acids, ribosomes, DNA, RNA, genes, chromosomes, transcription, and translation. Mitosis
is clearly defined and illustrated.
LEARNING OBJECTIVES
After viewing the program, students will…
■ Understand that all living organisms require energy.
■ Explain how plants create oxygen and glucose through photosynthesis.
■ Know that mitochondria perform cellular respiration to release energy molecules, which in
turn fuel the organism.
■ Understand that proteins are made up of amino acids and are created using information found
in the DNA molecule.
■ Explain how the RNA molecule copies genetic information from the DNA and carries it to the
ribosomes where proteins are produced.
■ Describe how cellular reproduction occurs through the five stages of mitosis.
EDUCATIONAL STANDARDS
National Standards
This program correlates with the National Science Education Standards developed by the National
Academy of Sciences and Project 2061 Benchmarks for Science Literacy from the American
Association for the Advancement of Science. The content has been aligned with the following
educational standards and benchmarks from these organizations.
■
■
■
■
■
■
■
Understands diversity and adaptations of organisms.
Understands biological evolution.
Understands reproduction and heredity.
Understands the molecular basis of heredity.
Understands the structure and function in living systems.
Understands the cell.
Understands 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.
■ Understands that every cell is covered by a membrane that controls what can enter and leave
the cell. In all but quite primitive cells, a complex network of proteins provides organization
and shape and, for animal cells, movement.
■ Understands that cells repeatedly 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.
2
Copyright © 2004 Cambridge Educational ®
■ Understands that within every cell are specialized parts for the transport of materials, energy
transfer, protein building, waste disposal, information feedback, and even movement. In addition, most cells in multi-cellular organisms perform some special functions that others do not.
■ Understands that within cells, many of the basic functions of organisms—such as extracting
energy from food and getting rid of waste—are carried out. The way in which cells function is
similar in all living organisms.
■ Understands that the work of the cell is carried out by the many different types of molecules it
assembles, mostly proteins. Protein molecules are long, usually folded chains made from 20
different kinds of amino-acid molecules. The function of each protein molecule depends on its
specific sequence of amino acids and the shape the chain takes is a consequence of attractions between the chain’s parts.
■ Understands that about two thirds of the weight of cells is accounted for by water, which
gives cells many of their properties.
■ Understands that the genetic information encoded in DNA molecules provides instructions for
assembling protein molecules. The code used is virtually the same for all life forms. Before a
cell divides, the instructions are duplicated so that each of the two new cells gets all the necessary information for carrying on.
■ Understands that complex interactions among the different kinds of molecules in the cell
cause distinct cycles of activities, such as growth and division. Cell behavior can also be affected by molecules from other parts of the organism or even other organisms.
■ Understands that gene mutation in a cell can result in uncontrolled cell division, called cancer.
Exposure of cells to certain chemicals and radiation increases mutations and thus increases the
chance of cancer.
■ Understands that most cells function best within a narrow range of temperature and acidity.
At very low temperatures, reaction rates are too slow. High temperatures and/or extremes of
acidity can irreversibly change the structure of most protein molecules. Even small changes in
acidity can alter the molecules and how they interact. Both single cells and multi-cellular
organisms have molecules that help to keep the cell’s acidity within a narrow range.
■ Understands that a living cell is composed of a small number of chemical elements, mainly carbon, hydrogen, nitrogen, oxygen, phosphorous, and sulfur. Carbon atoms can easily bond to
several other carbon atoms in chains and rings to form large and complex molecules.
Reprinted with permission from National Science Education Standards ©1999 by the National Academy of Sciences,
courtesy of the National Academies Press, Washington, D.C.
From BENCHMARKS FOR SCIENCE LITERACY by the American Association for the Advancement of Science, copyright 1993 by the American Association for the Advancement of Science. Used by permission of Oxford University
Press, Inc. Please note: judgments about the alignment of content presented here with the learning goals in BENCHMARKS FOR SCIENCE LITERACY are those of the author and do not represent the opinion or endorsement of the
AAAS or Oxford University Press, Inc.
English Language Arts Standards
The activities in this Teacher’s Guide were created in compliance with the following National
Standards for the English Language Arts from the National Council of Teachers of English.
■ Use spoken, written, and visual language to accomplish their own purposes (e.g., for learning,
enjoyment, persuasion, and the exchange of information).
■ Adjust their use of spoken, written, and visual language (e.g., conventions, style, vocabulary)
to communicate effectively with a variety of audiences and for different purposes.
3
■ Employ a wide range of strategies as they write and use different writing process elements
appropriately to communicate with different audiences for a variety of purposes.
■ Use a variety of technological and information resources (e.g., libraries, databases, computer
networks, video) to gather and synthesize information and to create and communicate knowledge.
■ Conduct research on issues and interests by generating ideas and questions, and by posing
problems. They gather, evaluate, and synthesize data from a variety of sources (e.g., print and
non-print texts, artifacts, people) to communicate their discoveries.
Standards for the English Language Arts, by the International Reading Association and the National Council of
Teachers of English, Copyright 1996 by the International Reading Association and the National Council of Teachers
of English. Reprinted with permission.
Technology Standards
The activities in this Teacher’s Guide were created in compliance with the following National
Education Technology Standards from the National Education Technology Standards Project.
■ Proficient in the use of technology.
■ Demonstrate a sound understanding of the nature and operation of technology systems.
■ Use a variety of media and formats to communicate information and ideas effectively to multiple audiences.
■ Use productivity tools to collaborate in constructing technology-enhanced models, prepare
publications, and produce other creative works.
■ Use technology tools to enhance learning, increase productivity, and promote creativity.
■ Use technology to locate, evaluate, and collect information from a variety of sources.
The National Education Technology Standards reprinted with permission from the International Society of Technology
Education.
PROGRAM OVERVIEW
This program introduces students to cells and their properties, including the shapes and sizes of
cells, functions of cells, eukaryotes and prokaryotes, the organization of cells, parts of the cell
and their functions, respiration, chromosomes and DNA, plant cells compared to animal cells,
photosynthesis, diversity of life on Earth, and the cell as the basic unit of life.
MAIN TOPIC AREAS
Topic 1: Energy Storage
This section begins with the premise that all living things require energy to survive, but the
method in which organisms capture, store, and release energy differs. Photosynthesis and cellular
respiration are then explained and compared.
Topic 2: Protein Synthesis
This topic identifies key organelles and their roles in the critical function of protein synthesis.
Amino acids, ribosomes, RNA, DNA, and genes are discussed followed by an overview and examples of how genetic disorders can be caused by mutations that occur during protein synthesis.
Topic 3: Cell Reproduction
In this section, the function of chromosomes is discussed, and the five stages of mitosis are
explained and illustrated.
4
FAST FACTS
■ An average plant cell is about three times larger than an animal cell.
■ The average life span for a stomach cell is two days; a brain cell can live for a lifetime.
■ The adult human body contains 5-6 quarts of blood, while an infant has about 1 quart of
blood.
■ The unfertilized ostrich egg is the world’s largest cell.
■ The human brain is made up of about one trillion nerve cells.
■ There are as many microbes in a single gram of soil as there are people in all of China.
■ An average person sheds 40 pounds of skin cells over a lifetime.
■ Direct sunlight causes the lysosomes in skin cells to burst. The enzymes released kill the cells of
the epidermis and lead to the blistering and peeling experienced with sunburn.
■ Lysosomes are responsible for the loss of a tadpole’s tail during metamorphosis. They digest
the tail and make the materials used to construct parts of the new frog.
■ There are over two hundred different types of cells in the human body.
VOCABULARY TERMS
cell: The fundamental unit that makes up all organisms on earth.
cell membrane: Also called the plasma membrane. The cell membrane regulates the flow of
materials into and out of the cell.
cell wall: Rigid structure surrounding the cell membrane of plant cells. It acts as a “skeletal system” for the cell by giving it support. Found in various forms in all kingdoms of organisms
except Animalia.
chloroplasts: Perform photosynthesis by taking in sunlight, water, and carbon dioxide to make
oxygen and sugar (a form of food). Also contain a green pigment called chlorophyll, which gives
plants a green color.
chromosomes: Long, thread-like bodies composed of DNA and protein, found in the nucleus of
eukaryotic cells. They contain the genes that contain the code for all the organism’s proteins.
cytoskeleton: The transparent network of protein filaments that maintains the cell’s shape,
holds organelles in place, and moves parts of the cell around if needed.
DNA (Deoxyribonucleic acid): The chemical that makes up all genes, and therefore chromosomes.
endoplasmic reticulum (ER): A folded membrane that moves materials around in the cell.
eukaryotic cell: A cell with a nucleus and other organelles with membranes around them.
Animal, plant, fungi and protista cells are eukaryotic.
golgi body (golgi apparatus): Package and move proteins to the outside of the cell.
lysosome: Contains enzymes that digest waste and worn out cell parts.
microbe: A minute, single-cell life form; a microorganism.
microorganism: An organism of microscopic or submicroscopic size.
mitochondria: Organelles where food molecules are broken down and energy is released.
nucleus: Control center of the cell where DNA is stored.
organelle: One of the structures found in the cell, which perform a function of the cell.
photosynthesis: The process in green plants and certain other organisms by which carbohydrates are synthesized from carbon dioxide and water using light as an energy source. Most
forms of photosynthesis release oxygen as a byproduct.
plant: An organism that uses photosynthesis to produce its own food. Its cells contain cellulose
and a cell wall.
prokaryotic cell: A cell that does not have a nucleus and other organelles with membranes
around them. Bacteria are examples of prokaryotic cells.
5
RNA (Ribonucleic acid): The chemical that “copies” the information from the DNA and carries
it to the ribosomes to be translated into protein.
ribosome: The site of protein synthesis, where the RNA is translated into protein.
vacuole: Vacuoles store water, food, pigments, waste, or other materials. Vacuoles are large in
plant cells and small in animal cells.
PRE-PROGRAM DISCUSSION QUESTIONS
1. How do living things get energy?
2. What do our bodies get from the food we eat?
3. It is often said that plants make their own food. What do they make?
4. Why do you need oxygen?
5. Do plants use oxygen?
6. Are all organisms made up of the same materials or chemicals?
7. What is DNA and what does it do for us?
8. What causes genetic diseases like Down Syndrome and Sickle Cell Anemia?
9. Where did your egg cell get its original set of chromosomes?
10. Do all of the cells in your body contain the same chromosomes?
POST-PROGRAM DISCUSSION QUESTIONS
1. Our cells are constantly dying or being replaced. How do we “know” how to build new cells?
2. Do all organisms have the same number of chromosomes?
3. Name some different types of proteins your body makes.
4. How can a single fertilized egg cell with only one set of chromosomes grow into a human
with many billions of cells?
5. What happens to the body if you do not eat or drink enough? How do you feel? How does
this relate to what occurs at the cellular level?
GROUP ACTIVITIES
Model DNA
Create a poster or 3-D model that illustrates the structure of DNA showing the links between A
and T, and C and G.
All in a Day’s Meal
Chart what each person in the group consumes in one day. Break down the food consumption
into approximate percentages of fat, carbohydrates, sugars, and proteins, and compile an average for each category. How does the group compare to the recommended daily allowance of
each?
INDIVIDUAL STUDENT PROJECTS
Eureka!
Research a historical discovery or theory related to cell biology or living organisms (evolution,
classification of organisms, DNA, microorganisms, etc.). Create a poster to illustrate your findings.
Mitosis Made Easy
Use household items such as clay, cardboard, yarn, etc. to construct a model of the phases of
mitosis. Show how and when chromosomes are copied, separated, and transported to form two
new nuclei.
6
What Goes Up…
Write a report on the importance of blood sugar (glucose) levels in our bloodstream.
INTERNET ACTIVITIES
The Birds and the Bees and Cells
Research a current event regarding cell reproduction, such as reproductive or therapeutic cloning,
gene therapy, genetic engineering, etc., and present your findings to the class in an oral presentation and one-page summary report.
It’s in the Genes
Research a genetic disease such as Down Syndrome or Cystic Fibrosis. What are the symptoms of
the disease? What is known about the causes? What treatments are currently available? What
kinds of research may affect future therapies?
The Top Twenty
Look up a list of the twenty essential amino acids found in proteins. Then visit an online pharmacy or health food site to see how many amino acids you can find for sale. What are these products purported to do?
The Numbers Game
We humans have 46 chromosomes in our cells. Find out the chromosome number of some other
animals, plants, and/or microorganisms and display them in a chart.
ASSESSMENT QUESTIONS
Q: Chromosomes are made up of DNA molecules. (True or False)
A: True
Feedback: The chromosomes store all a cell’s genetic information.
Q: Which organelle builds proteins?
(a) Golgi apparatus
(b) RNA
(c) Ribosome
(d) Gene
A: (c)
Feedback: The ribosome builds proteins out of 20 amino acids.
Q: A fertilized egg is called a _________________.
(a) zygote
(b) cell
(c) embryo
(d) clone
A: (a)
Feedback: A fertilized egg is called a zygote.
Q: The sun’s energy is stored in the glucose molecule inside the _____________.
(a) chlorophyll
(b) chloroplast
(c) cytoplasm
(d) protein
A: (b)
Feedback: The chloroplast stores the sun’s energy during photosynthesis.
7
Q: Plants use oxygen during cellular respiration. (True or False)
A: True
Feedback: Both plants and animal cells need oxygen to break down glucose molecules during
cellular respiration.
Q: Photosynthesis produces ____________________________.
(a) carbon monoxide and glucose
(b) carbon dioxide and glucose
(c) oxygen and glucose
(d) oxygen and energy
A: (c)
Feedback: Plants produce oxygen and glucose through photosynthesis.
Q: Cellular respiration produces _____________________.
(a) carbon monoxide, energy, and water
(b) carbon dioxide, glucose, and energy
(c) oxygen, glucose, and water
(d) carbon dioxide, water, and energy
A: (d)
Feedback: Energy, water, and carbon dioxide are released during cellular respiration.
Q: A gene is a portion of a chromosome that codes for a single protein. (True or False)
A: True
Feedback: Genes determine the physical characteristics of an organism.
Q: Zygotes grow into complete organisms by repeated cell division called _____________.
(a) photosynthesis
(b) mitosis
(c) respiration
(d) mitochondria
A: (b)
Feedback: Mitosis creates two identical daughter cells with a complete set of chromosomes.
Q: The chromosomes in the nucleus make copies of themselves in the phase of mitosis called
____________.
(a) anaphase
(b) interphase
(c) prophase
(d) telophase
A: (b)
Feedback: Interphase is the first stage of mitosis.
Q: Cellular respiration occurs in the mitochondria. (True or False)
A: True
Feedback: The mitochondria use oxygen to break down glucose molecules and release energy
molecules called ATP.
8
ADDITIONAL RESOURCES
WEB SITES
Communication Technology Lab of Michigan State University “Microbe Zoo”
www.commtechlab.msu.edu
The Franklin Institute Online: Living Things
www.fi.edu/tfi/units/life
Basic Principles of Genetics: An Introduction to Mendelian Genetics
http://anthro.palomar.edu/mendel/default.htm
Human Genome Project Information
www.ornl.gov/TechResources/Human_Genome/home.html
Life Science Connections—Life Science Safari
http://vilenski.org/science/safari
Cells alive!
www.cellsalive.com
PUBLICATIONS
The Cartoon Guide to Genetics by Larry Gonick, Mark Wheelis (Contributor). Harper Perennial,
1991. ISBN: 0062730991
Exploring The Way Life Works: The Science of Biology by Mahlon B. Hoagland, Bert Dodson,
Judith Hauck. Jones & Bartlett Pub., 2001. ISBN: 076371688X
The Origin of Species by Charles Darwin. Grammercy, 1998. ISBN: 0517123207
Other End of the Microscope: The Bacteria Tell Their Own Story, by Bert Dodson (Illustrator),
Eleanor S. Tupper (Editor), Elmer W. Koneman. American Society for Microbiology, 2002. ISBN:
1555812279
The Way Life Works by Mahlon Hoagland and Bert Dodson. Times Books, 1995.
ISBN:0812920201
9
OTHER PRODUCTS
Playing God: Human Cloning, VHS/DVD, Cambridge Educational
This program presents an in-depth exploration of the ethical concerns regarding human cloning.
A variety of perspectives are canvassed from the theological, legal, and scientific fields, including
interviews with Dr. Ian Wilmut, the first scientist to successfully clone a mammal—Dolly, a sheep.
Order #: 29332, www.cambridgeeducational.com, 1-800-468-4227
Cellular Respiration, VHS/DVD, Cambridge Educational
This six-part series begins by examining the essential fuels and machinery used by living forms to
sustain themselves. The fuel glucose is then broken down through the processes of glycolysis,
the Krebs cycle, and oxidative phosphorylation. Finally, the connections between the processes of
cellular respiration and nutrition are examined. The series includes The Cell and Energy, Glycolysis
1, Glycolysis 2, The Krebs Cycle, Oxidative Phosphorylation, Metabolism and Nutrition
Order #: 3668, www.cambridgeeducational.com, 1-800-468-4227
Sequencing Life, VHS/DVD, Cambridge Educational
In this program, Doctors Francis Collins, head of the Human Genome Project, and J. Craig
Venter, CEO of Celera Genomics, discuss the completion of the mapping of the human genome
and what that achievement means for the future of medicine. Initial discoveries indicate that the
structure of human DNA is simpler but its functions far more complex than previously imagined.
Order #: 29088, www.cambridgeeducational.com, 1-800-468-4227
10
For information on other programs
VISIT OUR WEBSITE AT
W W W. C A M B R I D G E E D U C AT I O N A L . C O M
2572 Brunswick Pike
Lawrenceville, NJ 08648
Toll Free: 1 800/468-4227
Fax: 1 800/FAX ON US
8230