Meiosis - Marcom Projects

Teacher’s Guide

Meiosis

Grades 5-9

MSTV

C R E D I T S

P r o g r a m P r o d u c t i o n

Te a c h e r ’s G u i d e

P r i n t M a t e r i a l D e s i g n

S u n b u r s t Vi s u a l M e d i a

Te r r y G a t e s

C e c i l e F o s h e e

© 2004 Sunburst Visual Media, a division of Global Video, LLC

Hawthorne, NY 10532

Approximate running time: 32 minutes

Meiosis Video Quiz

Table of

Contents

Guide Information ....................................

05

Fast Facts..................................................

07

Before Viewing Activities ..........................

10

During Viewing Activities ..........................

13

After Viewing Activities ............................

15

After Viewing Quizzes ..............................

18

Additional Resources ................................

23

Answer Keys ............................................

25

Script........................................................

32

© Sunburst Visual Media, a division of Global Video, LLC Meiosis Video Quiz

About This Guide

Guide

Information

Providing students with visual media is an excellent way to take them out of the classroom and into the real world. Our programs offer real-world footage, dynamic graphics, engaging dramatizations, and first-person testimonials that keep students interested and help them visualize difficult concepts. More importantly, they reinforce critical learning objectives shaped by state and national educational standards. However, the learning doesn’t begin and end when the program does. You can make the learning experience even more effective by using the materials provided in this Teacher’s Guide.

This guide is divided into the following sections:

• Fast Facts are designed to give your students a quick overview of the information presented within the video.

• Before Viewing Activities help identify what students already know about the subject, what they are curious about, and what they hope to learn.

• During Viewing Activities may be used during viewing to enhance students’ understanding of the video.

• After Viewing Activities help students summarize and draw conclusions from the information that was presented.

• After Viewing Quizzes test students’ retention of the information presented in the program and activity sheets.

• Additional Resources are designed to help you extend the information presented in the program into other areas of your curriculum.

• Answer Keys are provided for relevant activities or reproducible pages.

• Script content is provided in an unabridged version for future reference.


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© Sunburst Visual Media, a division of Global Video, LLC

Program Overview

Join Professor Science as he presents the basic concepts about meiosis. He covers what meiosis is, the main parts of the cell that are involved in the process, and the different stages of meiosis. The program is divided into two sections and at the conclusion of each one, interesting characters present multiple-choice and true/false questions to assess your students’ understanding of the concepts. At the conclusion of the program, the answers are provided so students can self-check their work.

Guide

Information

Viewing Objectives

Upon watching the Meiosis Video Quiz video/DVD, participating in the discussions, and completing the activities given in the program guide, students will be able to:

• Define the purpose of meiosis

• List and show the stages involved in the process of meiosis

• Compare basic differences between mitosis and meiosis

• Explain why meiosis is important to the creation of offspring

• Define key vocabulary related to meiosis

• Respond to multiple choice and true/false questions

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Meiosis Video Quiz © Sunburst Visual Media, a division of Global Video, LLC

Meiosis Fast Facts

1.

Meiosis is a process of cell division.

• Most organisms need meiosis to reproduce.

• Meiosis produces special cells that allow organisms to have offspring.

• These special cells are called germ cells.

2.

Every living thing is made of cells.

• Inside each cell are chromosomes that contain genetic information called genes.

• Genes determine who you are and what you look like.

3.

Every organism has a certain number of chromosome pairs.

• One set of chromosomes come from the mother and one set from the father.

• Paired chromosomes are called homologous.

• Homologous chromosomes have information about the same trait such as eye color.

4.

Each cell must have one pair of each type of chromosome.

• For example, human cells must have 23 pairs of chromosomes.

• Cells with the full number of chromosomes are called diploid cells.

• Most cells in the human body are diploid.

5.

Cells with only one of each type of chromosome in it are called haploid cells.

• Haploid cells have a total of 23 chromosomes, half of what a diploid cell has.

• Meiosis divides a diploid cell into four haploid cells after going through two divisions.

• A haploid cell is a special germ cell called a gamete.

6.

Gametes need to have only half of the proper number of chromosomes.

• When two human gametes fuse during fertilization, they pair up to a total of 23 pairs or 46 total.

• Two fused germ cells create a zygote with two sets of chromosomes.

• Zygotes form when a female germ cell has been fertilized by a male germ cell.

• Offspring develop from zygotes.

7.

In meiosis, one cell divides twice into four daughter cells.

• During meiosis, the chromosomes can exchange parts.

• All daughter cells differ somewhat from each other.

• Each daughter cell has only 23 chromosomes.

Fast Facts


7



8.

All cells enter the first stage of the cell cycle after they are newly formed.

• This stage is called interphase.

• During interphase, cells grow and DNA duplicates and produces another complete set of chromosomes.

• Then the cell begins the first of two stages of division.

9.

Prophase I

• Genetic material untangles from a chromatin form into a form of condensed chromosomes.

• Chromosomes become visible and ready to match up.

• They pair up with their homologue and form a tetrad.

• A tetrad is a four-stranded group of chromosomes joined at a point called the centromere.

• Each chromosome has four chromatids.

• While the tetrad is being formed, centrioles move to opposite ends of the cell.

• The centrioles produce spindle fibers.

• The nuclear membrane starts to break apart.

10.

Metaphase I

• The tetrads migrate towards the center of the cell and line up.

• They cross strands and exchange sections of DNA.

• This is called crossing-over or gene swapping.

• Crossing-over is important because it reorganizes the genetic information on the sister chromosome.

• This ensures diversity in the germ cells.

11.

Anaphase I

• The tetrads are pulled apart by the spindle fibers.

• Tetrads are pulled towards the poles at opposite ends of the cell.

• Each end now has two complete sets of chromosomes.

12.

Telophase I

• The nuclear membrane reforms around the two separate groups of chromosomes.

• Now the cytoplasm and organelles are divided up and the cell membrane pinches the cell into two cells.

• This process is called cytokinesis.

• The result is two daughter cells each with the normal number of chromosomes.

• The chromosomes are now diverse because they have exchanged genetic information.

Fast Facts

8



13.

All cells now enter the second stage of the cell cycle.

14.

Prophase II

• The chromatids are still in pairs attached at the centromere.

• The centrioles produce spindle fibers.

• The nuclear membrane starts to dissolve.

15.

Metaphase II

• The chromatids move to the center of the cell to line up again.

• The spindle fibers attach to the centromere of each chromosome pair.

• The nuclear membrane dissolves completely.

16.

Anaphase II

• The spindle fibers pull the chromosomes apart.

• The newly separated chromosomes travel to opposite ends of their cells.

• This separation guarantees diversity of the newly formed gametes.

17.

Telophase II

• Nuclear membranes form around the two new sets of daughter chromosomes.

• The cytoplasm and organelles divide.

• The cell membrane pinches the cells in half again.

• The result is four daughter cells and each contains half the chromosomes.

18.

In meiosis, the cells are genetically different.

• During the first phase of meiosis, one cell divides into two cells.

• It is these two cells that then divide and become four new gametes.

• The cells are genetically different because of crossing-over and random sorting of chromosomes.

• Each new cell that is created is a haploid cell.

Fast Facts


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Name Before Viewing

Activity 1

Before Viewing Discussion

Teacher Note: Prior to viewing the program, ask the following questions to help students focus on the topic. Space has been provided below for notes, additional questions, or their reflections on this activity.

1.

Why is meiosis important to all living things?

2.

How are the two stages of meiosis similar/different from each other?

3.

What are the steps of meiosis?

4.

Why are there two distinct stages of cell division during meiosis?

5.

How does meiosis guarantee similarities between generations of a species?

6.

Why do offspring have characteristics from both parents?

7.

How does meiosis guarantee diversity within a species?

NOTES:

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Name

Vocabulary

Teacher Note: Prior to watching the program, be sure to provide your students an opportunity to become familiar with the following vocabulary words and their meanings.

Before Viewing

Activity 2

1. reproduce

2. gametes

3. germ cells

4. zygote

5. chromosomes creation of an offspring from the cells of two parents sex cells; including sperm and eggs sperm and egg cells that allow organisms to reproduce a female germ cell that has been fertilized by a male germ cell and inherits one set of chromosomes from each parent thread-like bodies in a cell’s nucleus that contain the genetic information of that organism

6. meiosis

7. haploid cells

8. diploid cells a process of cell division that allows organisms to reproduce cells that contain only one set of chromosomes cells than contain two sets of chromosomes, each set from each parent

9. homologous chromosomes two chromosomes that are paired and have information about the same trait

10. somatic cells

11. daughter cell all cells besides egg or sperm cells new cells with half the chromosome number of the parent cell; human cells contain 23 chromosomes

12. tetrad

13. diversity

14. parent cell a four-strand group of chromosomes joined at a point differences in species

15. centromere cell with a complete set of chromosomes before cell division; human cells contain a complete set of 46 chromosomes the region of the chromosome where two identical chromatids are joined during meiosis

16. trait

17. crossing-over

18. cytokinesis

19. chromatids

20. spindle fibers a characteristic an exchange of genetic material between two chromatids the separation of a cell into two new cells identical chromosomes that hold genetic material such as eye color aid in pulling the chromosomes apart towards opposite poles of the cell


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Name Before Viewing

Activity 3

“I Want to Know” Questions

Teacher Note: Using the 5 W’s and HOW, allow students an opportunity to generate questions they have about meiosis. Two examples have been provided. Periodically, revisit and update the questions.

WHO

HOW

WHAT

What is meiosis?

WHY

Why is meiosis important to plants as well as animals?

WHERE

MEIOSIS

WHEN

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Name

Sequencing Meiosis

Fill in the missing information to make the graphic organizer complete. A few examples have been done for you.

Stage: Prophase I

This is what happens:

Stage:


During Viewing

Activity 1

Stage:


1

8

Stage:


7

2

3

4

Stage:


Pairs of chromosomes move to opposite ends of the cell towards poles

Stage:


Stage: Metaphase II


6


5

Stage:


Nuclear membrane disintegrates; chromosomes become attached to spindle fibers at centromeres and move toward center


13

Name

Meiosis Process

Graphic Organizer

Complete the graphic organizer.

There are two phases to the process of meiosis.

During Viewing

Activity 2

This process starts with ...

And the end result is ...

14


Name After Viewing

Activity 1

Oh Golly, Miss Dolly -

Genes for Sale!

Dolly the sheep was the first successfully cloned animal in 1997. Is genetic engineering a good idea? Do we have the right to clone living things?

Are we morally obligated to develop genetically engineered foods with the potential to feed everyone on Earth? Or are we opening Pandora’s Box?

Research and prepare both sides of a controversial issue that relates to genetics. Decide on two choices that could possibly address the issue. List pros and cons for both sides. Decide which choice would be the best one and write up a summary statement.

CHOICE #1: CHOICE #1:

Pro: Pro:

What’s the Issue?

Con:

Con:

Summary statement:


15


Activity 2

Dominant or Recessive?

Introduction – We all inherit genetic traits from our parents such as baldness, eye color, color blindness, as well as blood type. This activity will help you investigate which of the following traits are the result of dominant or recessive genes.

Directions – Look at each of the characteristics below. Decide which of the following traits you inherited from your parents. Mark the trait that best describes you.

16 pigmented iris [Are your eyes dark or light?] dark eyes (dominant) light eyes (recessive) hair type [Is your hair naturally curly or straight?] mostly curly (dominant) mostly straight (recessive) little finger [Does your pinky finger bend inward toward your ring finger?] bent (dominant) straight (recessive) tongue curling [Can you roll your tongue into a tube-like shape?] can curl (dominant) can’t curl (recessive) ear lobes [Do your ear lobes hang free or are they attached?] loose (dominant) attached (recessive) thumb crossing [When you clasp your hands together and interlock your fingers, which thumb naturally is on top?] left over right (dominant) right over left (recessive) hair on fingers [Do you have hair on one or more of the middle segments of your fingers?] hair on fingers (dominant) no hair on fingers (recessive) hitchhiker’s thumb [Do your thumbs bend backward to nearly a 90 ° angle?] can’t bend (dominant) can bend (recessive)

BONUS: After taking inventory of your genetic traits, tally up the results for your entire class.

Create various charts and graphs that share this information.


Name

Vocabulary Book

Use the following template to create a vocabulary book for terms related to meiosis.

After Viewing

Activity 3

Vocabulary word

_________________________________

Illustration with labels

Pronunciation

_________________________________

Definition

_________________________________

_________________________________

_________________________________

_________________________________

_________________________________

Word used in a sentence

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________


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Name

Meiosis Quiz

Circle the best answer for each question below.

1. The division of cells to create germ cells is called __________.

a. mitosis b. cytokinesis c. diploid split d. meiosis

2. True or False: During meiosis, only one cell division takes place.

3. Homologous means _____________________________.

a. same trait with different information b. same trait with the same information c. different traits with the same information d. different traits with different information

4. Chromosomes contain ____________________.

a. cells b. diploid cells c. genes, or genetic information d. zygotes

5. True or False: When germ cells combine, they create life.

6. Meiosis divides one diploid cell into ____________________.

a. 4 diploid cells b. 4 haploid cells c. 2 haploid cells d. 2 diploid cells

7. A gamete has ____________________.

a. 23 pairs of chromosomes b. 46 chromosomes c. 23 chromosomes d. A and B

8. A zygote has ____________________.

a. 1 set of chromosomes b. no chromosomes c. 23 chromosomes d. 2 sets of chromosomes

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After Viewing

Quiz 1


Name

Meiosis Quiz (cont.)


9. Our traits are determined from ____________________.

a. our germ cells b. our homologous cells c. our chromosomes d. None of the above

10. A germ cell is ____________________.

a. haploid b. diploid c. triploid d. sometimes haploid, sometimes diploid, never triploid

11. Crossing over is when ____________________.

a. sister chromosomes entangle and exchange DNA strands b. parent chromosomes entangle and exchange DNA strands c. chromosomes split d. daughter chromosomes split and form sister chromosomes

12. Meiosis II _________ the number of chromosomes of the parent cell.

a. maintains b. doubles c. reduces d. triples

13. True or False: In meiosis, the resulting cells have 23 pairs of chromosomes while in mitosis the resulting cells have 23 chromosomes.

14. When the cytoplasm and organelles divide at the end of meiosis I, it is called __________________. a. telophase I b. cytokinesis c. telekinesis d. metaphase II

15. A tetrad is ____________________.

a. a chromosome with two chromatids b. a chromosome with four chromatids c. a chromosomes with no chromatids d. None of the above

After Viewing

Quiz 1


19


Name

Meiosis Quiz ( cont.)


16. Which is the very last phase of Meiosis?

a. metaphase II b. anaphase I c. telophase II d. prophase II

17. Crossing over allows for ____________________.

a. more cells b. less cells c. each daughter cell to be identical d. each daughter cell to be unique

18. In the second phase of Meiosis, or Meiosis II, the two daughter cells divide into what?

a. 2 daughter cells with half the number of chromosomes b. 4 daughter cells with half the number of chromosomes c. 4 cousin cells with different chromosomes d. None of the above

19. True or False: The random sorting of chromosomes during anaphase II helps create unique gametes.

20. Which of the following are differences between mitosis and meiosis?

a. Number of times the cells divide b. Number of chromosomes in the parent cells c. Exchange of genetic information d. A and C

After Viewing

Quiz 1

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Quiz 2

Vocabulary Quiz A

Choose the vocabulary word to make each statement correct.

A. REPRODUCE

B. GAMETES

C. GERM CELLS

D. ZYGOTE

E. CHROMOSOMES

F. MEIOSIS

G. HAPLOID CELLS

H. DIPLOID CELLS

I. HOMOLOGOUS

CHROMOSOMES

J. SOMATIC CELLS creation of an offspring from cells of two parents sex cells; including sperm and eggs sperm and egg cells that allow organisms to reproduce a female germ cell that has been fertilized by a male germ cell and inherits one set of chromosomes from each parent thread-like bodies in a cell’s nucleus that contain the genetic information of that organism a process of cell division that allows organisms to reproduce cells that contain only one set of chromosomes cells that contain two set of chromosomes, each set from each parent two chromosomes that are paired and have information about the same trait all cells besides egg or sperm cells

1. The reproductive cells of the male (sperm) and female (eggs) are referred to as the

______________________.

2. All of an organism’s cells except the sperm or egg are ___________________.

3. Cells that contain only one set of chromosomes are ___________________.

4. A fertilized egg that has inherited a set of haploid cells from each parent is known as a(n) ____________________.

5. ______________ is a cell dividing process that only occurs in an organism’s sex cells.

6. A set of __________________________________________ pair up with the same type to determine such things as eye color or hair type in the offspring.

7. It’s the genetic information in your ________________________ that determines what you look and sound like.

8. Two parents combine their sperm and egg cells in order to ___________________.

9. Cells that enable organisms to have offspring are called ___________________.

10. Cells that contain the full number of chromosomes are called ___________________.


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22

Name

Vocabulary Quiz B


After Viewing

Quiz 3

A. TRAIT

B. DAUGHTER CELL

C. TETRAD

D. DIVERSITY

E. PARENT CELL

F. CENTROMERE

G. CROSSING OVER

H. CYTOKINESIS

I. CHROMATIDS

J. SPINDLE FIBERS a characteristic new cells with half the chromosome number of parent cells; human cells contain 23 chromosomes a four-strand group of chromosomes joined at a point differences in species cell with a complete set of chromosomes before cell division; human cells contain a complete set of

46 chromosomes the region of the chromosome where two identical chromatids are joined during meiosis an example of genetic material between two chromatids the separation of a cell into two new cells identical chromosomes that hold genetic material such as eye color aid in pulling the chromosomes apart towards opposite poles of the cell

1. Eye color is a(n) _________________ that is passed on from parent to child.

2. The ____________________ will receive half of the chromosomes from the parent cell.

3. During the early stages of meiosis, each chromosome is made of two identical

________________ that share identical genetic material such as hair color and height.

4. The process of ________________________ ensures that the genetic material from two parents will be exchanged, making the offspring similar yet unique.

5. Before cell division, each _____________________ has a complete set of chromosomes.

6. Species that display a lot of _____________________, or differences in characteristics, are more likely to survive.

7. The separation of one cell into two new cells is known as _______________________.

8. _____________________ are chromosomes with four chromatids.

9. The region of the chromosome where two identical chromatids are joined during meiosis is called the _______________________.

10. ________________________ help chromosomes migrate to opposite ends of the cell during meiosis.


Suggested Reading List

Bodmer, Walter. The Book of Man: The Human Genome Project and the Quest to Discover

Our Genetic Heritage.

The author covers a lot of scientific ground in this book, from Gregor Mendel’s discovery of the laws of inheritance to modern high-tech forensic science. Also explores the oftencontroversial topic of genetic engineering.

Dennis, Carina and Richard Gallagher. The Human Genome.

Mapping and sequencing of the human genome is considered by many to be humankind’s most important scientific discovery. Beautiful illustrations embellish this book as it takes the reader on a journey through everything from genetics and basic biology to a number of key players plus the political/social/ scientific impact of this incredible project.

Klotzko, Arlene Judith, editor. The Cloning Sourcebook.

This book is for the general reader as well as specialists in the field. Includes contributions from scientists who are responsible for some of the groundbreaking milestones in the development of cloning. Discusses cloning humans (for reproduction and for therapies), pets, and other animals.

Scientific American. Understanding Cloning.

This book is one of four titles in the Pocket Science series from the editors of Scientific

American science magazine. This book is a collection of essays on various topics relating to cloning. Asks thought provoking questions such as, “Should cloning be used to aid endangered species?” and “Can cloning help us equip old brains with new bodies?”

Snustad, D. Peter and Michael J. Simmons. Principles of Genetics.

This text makes a great first course in the study of genetics. Superb photography allows the reader to take hold of even the most complex of details. Discusses the Human

Genome Project, gene therapy, plus behavior genetics. Stresses key points, provides various questions and answers, includes unique conversations with researchers.

Wilmut, Ian, Keith Campbell, and Colin Tudge. The Second Creation: Dolly and the Age of

Biological Control.

Human cloning is today’s hot topic. This book provides the reader an opportunity to explore a scientific model for studying the interactions of genes and what surrounds them.

Additional

Resources


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Internet Sites

Below is a list of sites that you may use to find more information about meiosis. Due to routine web maintenance, not all of the links will be accurate at the time of access. If the link is not available, try to conduct a search on that topic from the main site or from a search engine.

Additional

Resources http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/main.html

This site will help your students to better understand the sequence of events that take place in the process of meiosis. Wonderful step-by-step tutorial.

http://www.accessexcellence.org/AB/GG/meiosis.html

Graphics are a strength at this site. Clear, outline format that explains the steps of meiosis.

http://www4.ncsu.edu/unity/users/b/bnchorle/www/

This is a great tutorial that simplifies the confusing but important steps of the process.

Attractive black background sets the stage for understanding clear graphics explaining the details.

http://www.rothamsted.bbsrc.ac.uk/notebook/courses/guide/meiosis.htm

This site includes a wonderful animation that breaks the stages on meiosis into clear and simple steps. Each frame has a short description of the action that is taking place.

http://www.johnkyrk.com/meiosis.html

Contains colorful animations with stages highlighted that gives a visual explanation of what happens during the process of meiosis. One of the best sites out there in terms of animation presentation.

http://tutor.lscf.ucsb.edu/mcdb/tutorial/meiosis/

A bit more advanced and goes into greater detail than some of the other sites.

http://www.pbs.org/wgbh/nova/baby/divide.html/

This site does a wonderful job of comparing two colorful action packed animations. It very clearly shows the difference between the stages of meiosis and mitosis. http://genetics-eductiona-partnership.mbt.Washington.edu/default.htm

Includes various education guides and instructional materials for classroom use. Also, PDF files for download and suggested genetics web resources. http://stats.bls.gov/k12/html/edu_over.htm

Links to various career sites covering science and genetics related careers. Includes teacher’s guide, career information, and educational resources. http://www.newscientist.com/hottopics/cloning/

Contains up to date articles that pertain to the latest advancements in science.

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Answer Key - During Viewing Activity Sheet 1

Sequencing Meiosis

Fill in the missing information to make the graphic organizer complete. A few examples have been done for you.

Stage: Prophase I


Chromosomes condense; nuclear membrane disappears; crossover may occur

Stage: Metaphase I


Chromosomes align in the middle of the cell; two chromosomes to each spindle fiber

Stage: Telophase II


Nuclear membrane forms around newly divided chromosomes; chromosomes begin to fade; cytokinesis occurs again

8

1 2

3

Stage: Anaphase I


Pairs of chromosomes move to opposite ends of the cell towards poles

Stage: Anaphase II


Centromeres split and chromatids move to the poles

Stage: Metaphase II


Chromosomes line up in middle of cell

7

6

4

Stage: Telophase I


Cytokinesis occurs

(cell pinches into two new daughter cells)

5

Stage: Prophase II


Nuclear membrane disintegrates; chromosomes become attached to spindle fibers at centromeres and move toward center


25


Answer Key - During Viewing Activity Sheet 2

Meiosis Process

Graphic Organizer

Complete the graphic organizer.

There are two phases to the process of meiosis.

This process starts with ...

Interphase

Prophase I Metaphase I

Prophase II Telophase I Anaphase I

Metaphase II Anaphase II Telophase II

And the end result is ...

the production of eggs and sperm for sexual reproduction.

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Answer Key - After Viewing Quiz 1

Meiosis Quiz


1. The division of cells to create germ cells is called __________.

a. mitosis b. cytokinesis c. diploid split d. meiosis

2. True or False: During meiosis, only one cell division takes place.

3. Homologous means _____________________________.


4. Chromosomes contain ____________________.



6. Meiosis divides one diploid cell into ____________________.


7. A gamete has ____________________.


8. A zygote has ____________________.

a. 1 set of chromosomes b. no chromosomes c. 23 chromosomes d. 2 sets of chromosomes


27


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9. Our traits are determined from ____________________.

a. our germ cells b. our homologous cells c. our chromosomes d. None of the above

10. A germ cell is ____________________.

a. haploid b. diploid c. triploid d. sometimes haploid, sometimes diploid, never triploid

11. Crossing over is when ____________________.


12. Meiosis II _________ the number of chromosomes of the parent cell.


13. True or False: In meiosis, the resulting cells have 23 pairs of chromosomes while in mitosis the resulting cells have 23 chromosomes.

14. When the cytoplasm and organelles divide at the end of meiosis I, it is called __________________. a. telophase I b. cytokinesis c. telekinesis d. metaphase II

15. A tetrad is ____________________.

a. a chromosome with two chromatids b. a chromosome with four chromatids c. a chromosomes with no chromatids d. None of the above






a. metaphase II b. anaphase I c. telophase II d. prophase II

17. Crossing over allows for ____________________.

a. more cells b. less cells c. each daughter cell to be identical d. each daughter cell to be unique


a. 2 daughter cells with half the number of chromosomes b. 4 daughter cells with half the number of chromosomes c. 4 cousin cells with different chromosomes d. None of the above


20. Which of the following are differences between mitosis and meiosis?



29



Vocabulary Quiz A


A. REPRODUCE

B. GAMETES

C. GERM CELLS

D. ZYGOTE

E. CHROMOSOMES

F. MEIOSIS

G. HAPLOID CELLS

H. DIPLOID CELLS

I. HOMOLOGOUS

CHROMOSOMES

J. SOMATIC CELLS creation of an offspring from cells of two parents sex cells; including sperm and eggs sperm and egg cells that allow organisms to reproduce a female germ cell that has been fertilized by a male germ cell and inherits one set of chromosomes from each parent thread-like bodies in a cell’s nucleus that contain the genetic information of that organism a process of cell division that allows organisms to reproduce cells that contain only one set of chromosomes cells that contain two set of chromosomes, each set from each parent two chromosomes that are paired and have information about the same trait all cells besides egg or sperm cells

1. The reproductive cells of the male (sperm) and female (eggs) are referred to as the

4. A fertilized egg that has inherited a set of haploid cells from each parent is known to determine such things as eye color or hair type in the offspring.

you look and sound like.

30



Vocabulary Quiz B


A. TRAIT

B. DAUGHTER CELL

C. TETRAD

D. DIVERSITY

E. PARENT CELL

F. CENTROMERE

G. CROSSING OVER

H. CYTOKINESIS

I. CHROMATIDS

J. SPINDLE FIBERS a characteristic new cells with half the chromosome number of parent cells; human cells contain 23 chromosomes a four-strand group of chromosomes joined at a point differences in species cell with a complete set of chromosomes before cell division; human cells contain a complete set of

46 chromosomes the region of the chromosome where two identical chromatids are joined during meiosis an example of genetic material between two chromatids the separation of a cell into two new cells identical chromosomes that hold genetic material such as eye color aid in pulling the chromosomes apart towards opposite poles of the cell

3. During the early stages of meiosis, each chromosome is made of two identical parents will be exchanged, making the offspring similar yet unique. are more likely to survive.

9. The region of the chromosome where two identical chromatids are joined during during meiosis.


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Script

C

AST

Professor Science ....................................................host

Victor Velocity ............................................racecar driver

Quiz Clown ............................................................clown

Ricky Wave ................................................................DJ

Star Struck ..........................................................reporter

Fizzle ........................................................................genie

Wendy River ........................................................cowgirl

Nuke Rockney ......................................................coach

Sandy Space ....................................................astronaut

Salty Gales ............................................................pirate

Quizitor ....................................................................robot

S

CENE

1

PROFESSOR SCIENCE

Hello there! Welcome to another wacky episode of the Wonderful World of

Science, starring…. Me, PROFESSOR SCIENCE!! Today’s topic is about division! No, not the mathematical kind of division, we are talking a type of cell division – Meiosis!! Yeah, yippee!! Don’t worry; by the end of this show you’ll be as crazy about Meiosis as I am!! With the help of a few friends who will quiz you on the main topics, this whole Meiosis thing will be a breeze!!

Meiosis is a process of cell division, but not just any cell division. You may have heard of mitosis, the division of regular somatic cells. Meiosis produces different cells, the cells that allow organisms to reproduce. These cells are called germ cells.

Before we can get into Meiosis, let me give you a little background on chromosomes. Every living thing is made of cells. Inside these cells are chromosomes. Chromosomes contain genetic information, or genes, that determine who you are and what you look like; they even determine if you are a boy or a girl!

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Every organism has a certain number of chromosome pairs in their cells. For example, onion plants have 8 pairs of chromosomes. Tomato plants have 12 pairs. Goldfish have 47 pairs, and humans have 23 pairs of chromosomes.

The chromosome number of an organism isn’t related to its size or composition. Let’s take a look! A giant sequoia tree can grow to a height of about 250 feet, and it has 22 chromosomes. Grasshoppers are about two inches long, and have 24 chromosomes.

Chromosomes come in pairs; one chromosome comes from your mother and the other from your father. Your paired chromosomes are called homologous because both chromosomes have information about the same trait or characteristic, like eye color. But, the information is different for each characteristic because it is coming from two different people!

Since the chromosomes in the pair come from different people, this is how our traits are determined. This is also what makes us individuals. It’s kind of like having two sets of instructions to put a bike together, one from the bike manufacturer and one from the manufacturer of another type of bike. Both instructions tell you how to assemble the bike. One instruction sheet might suggest larger tires and the other might say to add fenders. So the bike turns out differently than each sheet said because you took information from two different sheets and combined them.

Now, these chromosome pairs are very important. In order for a cell to function properly, it must have one pair of each type of chromosome. This means, for a human cell to work, it must have 23 pairs of chromosomes. A cell that has the full number of chromosomes is called a diploid cell. Almost all of the cells in the human body are diploid. Your heart, bone and skin cells are all diploid, having 46 chromosomes total. Scientists refer to the diploid chromosome number as “2N.” This represents the total number of chromosomes in the cell, which is the number of chromosome pairs, multiplied by 2!

For example, a fruit fly has 4 pairs of chromosomes. What is its diploid chromosome number? Think! That’s right! A fruit fly has a diploid number of

8 because it has four pairs, multiplied by two, equaling eight! Great job! Let’s move on, geniuses!


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Now, if a cell had only one of each type of chromosome in it, it would be called a haploid cell. Your haploid cells only have 23 chromosomes total. This is where meiosis comes in!

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Meiosis is extremely important! Why, without it, none of us would exist!!

Most organisms need meiosis to reproduce! Meiosis only takes place in the reproductive organs. The cells that Meiosis creates are essential for the reproduction process. You see, meiosis is the division of cells to create a special kind of cell, a germ cell.

Meiosis divides a diploid cell into four haploid cells by going through two divisions. So from one somatic cell, the division produces four germ cells that can be used in reproduction.

A haploid cell has half of the chromosomes as a diploid cell. These special germ cells are called gametes. So, at the end of meiosis, each human gamete has a total of 23 chromosomes. Scientists symbolize the haploid chromosome number by using an “N.” Just like the diploid symbol, N represents the number of chromosomes.

If a guinea pig has 64 chromosomes in each of its diploid cells, what would be its haploid cell number or “N”? I’ll give you a few seconds, good luck!

(pause for a few seconds) Got it? The answer is 32! Because there are 64 total, you have to cut that number in half!

It is important for the gamete to have only half of the proper number of chromosomes because when two gametes fuse during fertilization, their chromosomes pair up and total 46, or 23 pairs. Two fused germ cells create a zygote with two sets of chromosomes. A zygote is a female germ cell that has been fertilized by a male germ cell. From that zygote, an offspring develops.

All right! Let’s take a break and answer some questions. When we come back, we will learn the stages of meiosis. Are you ready for the first round of questions?! Good Luck!!

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VICTOR VELOCITY

Vroom, Vroom, Vroom, Screeeech!!!!!!!!!!! Whew! Looks like I stopped by just in the nick of time! I’ve got a quick question for you and then it’s back to the race!!

1. The division of cells to create germ cells is called__________.

a. Mitosis b. Cytokinesis c. Diploid split d. Meiosis

What a way to start off the quiz! I hope you wrote down an answer. Now get in gear and move to the next question.

QUIZ CLOWN

Boy! Balancing on a high wire with these big shoes on sure is hard work!

While I take a balance break, see if you can answer this!

2. True or False: During Meiosis, only one cell division takes place.

Hmmm. Write down your answer and let’s move on to the next question.

My feet are cramping up in these shoes!

RICKY WAVE

Hello faithful listeners of SQRD- science quiz radio. Ricky Wave here to bring you the latest sounds from the underground. So tune in to…

3. Homologous means ________________________________.


Lots of words, but it had a great beat. Write down your answer and let’s tune into the next question!


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STAR STRUCK

Hi everyone, Star Struck at the latest movie premiere- “Meiosis and

Me.” I’m here to present… the next question!

4. Chromosomes contain __________________.


How did you do? Pick an answer and write it down. I’m off to do my close-up now! How does my hair look?

FIZZLE

If you get my question right, I just may grant you three wishes!!


Hmmm. That’s very interesting. What do you think? Pick true or false and get it on paper. Oh, I’ve gotta go! Someone is just taking a test and is wishing for a good grade!

WENDY RIVER

Well, howdy! Before the roundup here, let’s lasso up a question for y’all.

6. Meiosis divides one diploid cell into __________________.


Well, what do you think, pardner? Choose your answer wisely and write it down. I’m off to lasso class, but I’ll see y’all a little later!


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NUKE ROCKNEY

(Blows whistle) Ok team, you are doing a great job! Keep up the good work! Remember to use those brains! You know the answer to this!

7. A gamete has __________________.


Well, how did you do? Pick an answer and write it down. You can do it!

Go team go!

SANDY SPACE

Hi everyone, Sandy Space broadcasting live from the Space Station. Turn on all your rocket boosters to answer this!

8. A zygote has __________________.

a. 1 set of chromosomes b. No chromosomes c. 23 chromosomes d. 2 sets of chromosomes

What do you think? Write your answer down while I call ground control.

SALTY GALES

Well, shiver-me-timbers, maties! Get this right and the treasure map of knowledge is yours!

9. Our traits are determined from __________________.

a. Our germ cells b. Our homologous cells c. Our chromosomes d. None of the above

Aye, how did you do? Write yer answer down matey while I set sail with me crew!


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QUIZITOR

Hello. I am Quizitor. Show me that you are a great scientist by answering this question correctly! Good luck!

10. A germ cell is __________________.

a. Haploid b. Diploid c. Triploid d. Sometimes haploid, sometimes diploid, never triploid

What do you think? Pick an answer and write it down. It’s time for me to log off, but here’s Professor Science with more information. That is all.

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I’m back!! How were the questions? Not too bad, I imagine! Now, as you probably remember from mitosis, scientists refer to the original cell as the parent cell, the original pairs of chromosomes as sister chromosomes, the new chromosomes as daughter chromosomes, and the new cells as daughter cells.

Before we get to the specifics of meiosis, let’s review the stages of mitosis, or regular cell division. Do you remember the four stages?! Think real hard!

(short pause) You got it! They are Prophase, Metaphase, Anaphase, and

Telophase.

Well, the cell cycle and the phases of mitosis are similar to meiosis! But there are some important differences. As I just said, in mitosis, one cell divides into two daughter cells, and in meiosis, one cell divides twice into four daughter cells. In meiosis, the chromosomes can exchange parts. They don’t do that in mitosis. The daughter cells in meiosis differ from each other, while the daughter cells in mitosis are identical to their parent cell. And the most important difference between the two is that in meiosis, the four daughter cells have only 23 chromosomes in them, while in mitosis, each cell has 23 pairs.

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All cells enter the first stage of the cell cycle after they are newly formed. That stage is called interphase. During interphase, cells grow, and DNA duplicates to produce another complete set of chromosomes. When the cell is ready,

Meiosis begins the first division.

We number each phase, since the cells undergo two different divisions. In prophase I, the genetic material untangles from chromatin form into condensed chromosomes. The chromosomes become visible and ready to match up. They then pair up with their homologue to form a tetrad. A tetrad is a four-stranded group of chromosomes joined at a point called the centromere. Basically, each chromosome has four chromatids. While the tetrad is being formed, centrioles move to opposite ends of the cell to form poles. The centrioles produce spindle fibers. Also in this early stage, the nuclear membrane starts to break apart.

Metaphase I is next! The tetrads migrate towards the center of the cell, and line up. While the tetrads are pairing off and lining up, they cross strands and exchange sections of DNA. This is called crossing over. Crossing over, or gene swapping as it is sometimes called, reorganizes the genetic information on the sister chromosomes. This provides diversity in the germ cells. That’s why you look similar to your siblings, but not identical!

In anaphase I, the tetrads are pulled apart by the spindle fibers. Now they are pulled towards the poles at opposite ends of the cell, each end having two complete sets, or 23 pairs of chromosomes.

Lastly, the cell moves into telophase I, where the nuclear membrane is reformed around the two separate groups of chromosomes. At this point, the cytoplasm and organelles are divided up, and the cell membrane pinches the cell into two cells. This process is called cytokinesis. The result is two daughter cells, each with the normal number of chromosomes. And remember, none of these cells are identical to each other because the chromosomes have exchanged genetic information.


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Now the second phase of meiosis, or meiosis II begins. In prophase II, the chromatids are still in pairs attached at the centromere. Once again, the centrioles produce spindle fibers, and the nuclear membrane starts to dissolve.

Next, the chromatids move to the center of the cell to line up once more in metaphase II. The spindle fibers attach to the centromere of each chromosome pair. The nuclear membrane completely dissolves.

In anaphase II, the spindle fibers pull the chromosomes apart, and the newly separated chromosomes travel to opposite ends of their cells. The key difference from mitosis happens in this stage.

Remember how one chromosome from each pair is from the mother and one from the father? Well, now the paired chromosomes are split up and sorted randomly to opposite poles. Since only one chromosome of each pair ends up at each pole, the diversity becomes much greater between the newly formed gametes.

In the last stage, Telophase II, nuclear membranes form around the two new sets of daughter chromosomes. The cytoplasm and organelles divide, and the cell membrane pinches the cell in half once again. And there you have it – four daughter cells, each with half the chromosome number!

Remember, during the first phase of meiosis, one cell became two cells. Both of those cells went through the second phase to create a total of four new gametes.

As I mentioned before, the neat thing about meiosis is that the cells are genetically different. The crossing over of genetic information and the random sorting of chromosomes ensure that each daughter cell is unique. Since each new cell that is created is a haploid cell, the chromosome number is restored during fertilization, and there will be even more genetic mixing!

And there you have meiosis! Pretty cool stuff, isn’t it? I know you have this down pat and to prove it; here comes my friends to see how smart you are!


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VICTOR VELOCITY

Vroom, Vroom, Vroom!!!!!!!!!! Time for a quick pit stop and another question for you!

11. Crossing over is when __________________.


What do you think? Write down your answer and get back in the race!

QUIZ CLOWN

Hi again! You are just in the nick of time! I was about to have a pie thrown in my face! Now that you’re here, it won’t happen! (whipped cream pie is thrown at her). Or…I could be mistaken. Here’s a not so messy question for you.

12. Meiosis II ________ the number of chromosomes of the parent cell.


So, what do you know? Can you figure it out? Put your answer down and wait right here for further instructions…(turns around, grabs pie and pretends to throw pie at camera)

RICKY WAVE

Hello all you out there in radio land. Ricky Wave here bringing you the latest tunes from the new band- MEIOSIS. Let’s listen…

13. True or False: In meiosis, the resulting cells have 23 pairs of chromosomes while in mitosis the resulting cells have

23 chromosomes.


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That was fab-u-lous! I’m sure you’ve got an answer written down. Don’t change that dial; we’ve got more great tunes ahead!

STAR STRUCK

Hello to all my fans out there! This is Star Struck bringing you the latest dish from science quiz. I heard the following from a reliable source…

14. When the cytoplasm and organelles divide at the end of meiosis I, it is called __________.

a. Telophase I b. Cytokinesis c. Telekinesis d. Metaphase II

Wow! That was some news! I hope you figured it out and wrote down an answer. I’d love to hear it, but I just saw my favorite movie star in the world and I have to get an autograph!

FIZZLE

I’m back! I just had to come out of my bottle for this next question!

15. A tetrad is __________________.

a. A chromosome with two chromatids b. A chromosome with four chromatids c. A chromosomes with no chromatids d. None of the above

Very interesting. What do you think? Write your answer down and I may stay out of my bottle a little longer.

WENDY RIVER

Whew! That bronco was a tough one! While I try to catch my breath, let’s see if you can rope this next problem!

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a. Metaphase II b. Anaphase I c. Telophase II d. Prophase II

Hmm. How did you do? Put yer answer down and let’s saddle up for the next rip-roaring question!

NUKE ROCKNEY

(Blows whistle) Ok team, this is kind of a tough play I’m about to show you. But with some concentration, I’m sure you will all get it!

17. Crossing over allows for __________________.

a. More cells b. Less cells c. Each daughter cell to be identical d. Each daughter cell to be unique

Go team go! You pick an answer and let’s get back in formation! Let’s move it out!

SANDY SPACE

Sandy Space zooming in from outer space to give the next question.

Listen up!


a. 2 daughter cells with half the number of chromosomes b. 4 daughter cells with half the number of chromosomes c. 4 cousin cells with different chromosomes d. none of the above

So what do you think? Write down an answer and I’ll boost you on to the next question.


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SALTY GALES

Ahoy maties!! Another correct answer and you can be my first mate!


What’s yer answer? Write it down quick before me and my crew come sailing after you!

QUIZITOR

Hello. I am Quizitor. I’ll take break from my latest experiment to quiz you!

Hope you all get this one right!

20.

Which of the following are differences between mitosis and meiosis?


Get your final answer down. It’s time again to see Professor Science.

Thank you. This is Quizitor— logging off.

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Hey, you did it! You are so smart! Well, that is all I have for you today on the

Wonderful World of Science! Stay tuned for a complete list of answers. See you next time!!

ANSWERS

1.

d.

The division of cells to create germ cells is called meiosis.

2 . False.

A gamete is the result of a germ cell dividing twice.

3.

a.

Homologous means same trait with different information.

4.

5.

6.

7.

c.

Chromosomes contain genes, or genetic information.

True.

When germ cells combine, they create life.

B.

c.

Meiosis divides one diploid cell into 4 haploid cells.

A gamete has 23 chromosomes.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

d.

c.

A zygote has 2 sets of chromosomes.

Our traits are determined from our chromosomes.

a.

a.

A germ cell is haploid.

Crossing over is when sister chromosomes entangle and exchange DNA strands.

c.

Meiosis II reduces the number of chromosomes of the parent cell.

False.

In meiosis, the resulting cells have 23 chromosomes while in mitosis, the resulting cells have 23 pairs of chromosomes.

b.

When the cytoplasm and organelles divide at the end of meiosis I, it is called cytokinesis.

b.

A tetrad is a chromosome with four chromatids.

c.

d.

Telophase II is the very last phase of Meiosis.

Crossing over allows for each daughter cell to be unique.

b.

In the second phase of Meiosis, or Meiosis II, the two daughter cells divide into 4 daughter cells with half the number of chromosomes.

True.

Random sorting of chromosomes increases gamete diversity.

d.

Mitosis and meiosis differ in the number of cell divisions and in the exchange of genetic information.


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