Y CL, REPRODUCT HRT one makes two, and four, …and trillionsLS 3.7.8 Identify the number and source of chromosomes in human body cells. LS 3.7.10 Explain the role of cell division

one makes two, and four, …and trillionspart two: cell division and reproduction

Life CyCLes, RepRoduCtion & HeRedity

ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.

Frameworks

sCIeNCeLS 3.6.2 Predict the outcome of selective breeding practices over several generations.LS 3.7.1 Explain that the fertilized egg cell carries genetic information from each parent and multiplies to form a complete organism.LS 3.7.2 Distinguish between sperm and egg cells. LS 3.7.3 Compare and contrast the structure and function of the sperm cell and the egg cell in vertebrates and plants and their role in sexual reproduction. LS 3.7.8 Identify the number and source of chromosomes in human body cells.LS 3.7.10 Explain the role of cell division.LS 3.8.2 Differentiate between dominant and recessive traits.

LaNGUaGe arTsOV.2.6.1 Demonstrate effective listening skills by exhibiting appropriate body language. OV.2.7.1 Demonstrate effective listening skills by exhibiting appropriate body language. OV.2.8.1 Demonstrate effective listening skills by exhibiting appropriate body language.

s objeCTIvesThe students will learn:

objeCTIve #1 To describe the difference between body cells and reproductive cells.

objeCTIve #2 To define meiosis.

objeCTIve #3 To distinguish between diploid and haploid cells.

objeCTIve #4 To explain how in sexual reproduction, the zygote contains genetic material from both parents.

objeCTIve #5 To appropriately use verbal speaking skills in class discussion with the teacher and Garden Program Specialist.


Page 2 LIFE CYCLES, REPRODuCTIOn & HEREDITY • One Makes Two…, Part 2: Teachers’ Guide

All

livin

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at m

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ly through mitosis and reproduce through m

eiosis.

overvIewAll living organisms consist of cells. Body cells multiply through mitosis, or cell division. All body cells share the same hereditary material. Reproductive cells undergo meiosis to split pairs of chromosomes into single sets. A fertilized egg carries a single set of chromosomes each from the father and mother.

GardeN aCTIvITIes▲s Collecting eggs

▲s Plant, harvest and work in the garden following the Garden Guide

▲s Recipes and taste tests as time permits (refer to Delta Garden Study Recipe Book)


LIFE CYCLES, REPRODuCTIOn & HEREDITY • One Makes Two…, Part 2: Teachers’ Guide Page 3

TIps For THe CLassroomPre-lesson preparation:

1. Determine how the “Chromosome Structure” visual will be used and prepare appropriately.

LessoN oUTLINe

activities estimated duration actual duration

in the classroom

▲s Offer the icebreaker

▲s Explain the difference between body cells and reproductive cells

5 minutes

5 minutes

▲s Explain meiosis, define diploid and haploid

10 minutes

in the garden ▲s Observe chickens, collect eggs. Explain sexual reproduction of chickens.

5 minutes

▲s Plant, harvest and work in the garden following the Garden Guide

15 minutes

back in the classroom

▲s Hand out Student Learning Workbooks, review and assign “Take it Home Activity” as homework

5 minutes

TIps For THe GardeNPre-lesson preparation:

1. Prepare to discuss student observations of chickens and the reproduction process of chickens including meiosis, the number of chromosomes in diploid and haploid cells, etc.

2. Prepare materials for chicken tending activities.

classroommaterials needed

▲s Student Workbooks

▲s Materials needed for the optional class activity

gardenmaterials needed

▲s Appropriate tools for garden activities



LessoN pLaN

I. Start in the classrooma. Icebreaker

Ask students: “How many eggs can a hen lay a year?”

AnSWER: “A hen can lay anywhere from 100-300 eggs per year, but she can only lay one egg per day.”

b. present main Topic▲s Revisit the difference between body cells and reproductive

cells and their functions. meeTs objeCTIve #1

▲s Displaying the Visual page, explain meiosis. Reproductive cells undergo meiosis to maintain the number of chromosomes of the species. Through meiosis, the zygote receives a set of chromosomes from each parent, which then team up to form a complete pair. Compare and contrast mitosis and meiosis. Define diploid and haploid.

meeTs objeCTIves #2–5

II. Take class to the garden▲s Instruct students to gather eggs and observe chickens. Explain

reproduction of chickens.meeTs objeCTIves

#1–4▲s Plant, harvest and work in the garden following the Garden Guide.

▲s Taste available produce. Ask students for feedback.

III. Take class back to classroom▲s Hand out the Student Learning Workbook as reference material

and class assignment. Review take it home activities and encourage students to do them.

meeTs objeCTIve #6



sUpporTING INFormaTIoN For TeaCHers

baCkGroUNd

In sexual reproduction, a new organism forms as a result of fertilization. A male reproductive cell, the sperm, joins a female reproductive cell, the egg, to create a zygote. The zygote is made up of body cells, not reproductive cells, so it develops into a mature organism through—you guessed it—mitosis cell division.

Then mitosis also facilitates the regeneration of an organism’s cells, as when skin tissue heals.

Eventually at a single point of that organism’s life, usually at maturity, meiosis will take place in the reproductive cells of the organism’s egg or testis, not in the organism’s body cells. Meiosis ensures that reproductive cells are haploid cells, meaning that each cell contains only a single set of chromosomes, a single set being 23 chromosomes in humans.

Meiosis consists of two steps, meiosis I and meiosis II, and four phases in each step. These phases are called prophase, metaphase, anaphase and telophase, just like during mitosis. However, even though the names are the same, the developments that happen in these four phases during meiosis are not the same as the ones during mitosis. At the end of meiosis, the nucleus has split twice, resulting in four reproductive cells, or germ cells, each containing one-half the number of chromosomes that was in the original nucleus. Only reproductive cells undergo meiosis, not body cells.

A single parent diploid cell (two homologous chromosome pairs) divides to produce four daughter haploids cells (one homologous chromosome of the pair).

Four phases of meiosis:

Interphase: Before meiosis begins, genetic material is duplicated.

First division of meiosis

Prophase 1: Duplicated chromatin condenses. Each chromosome consists of two, closely associated sister chromatids.

Metaphase 1: Homologous chromosomes align at the equatorial plate.

Anaphase 1: Homologous pairs separate with sister chromatids remaining together.

Telophase 1: Two “daughter” cells are formed with each daughter containing only one chromosome of the homologous pair.

Second division of meiosis: Gamete formation

Prophase 2: DnA does not replicate.

Metaphase 2: Chromosomes align at the equatorial plate.

Anaphase 2: Centromeres divide and sister chromatids migrate separately to each pole.

Telophase 2: Cell division is complete. Four haploid “daughter” cells are obtained.

Meiosis ensures that reproductive cells contain only single sets of chromosomes. You’ll want to remember these main facts:

▲s One parent cell produces four “daughter” cells.

▲s “Daughter” cells have half the number of chromosomes found in the original parent cell.

▲s Meiosis differs from mitosis primarily because there are two cell divisions in meiosis, resulting in cells with a haploid number of chromosomes.

After this process of meiosis in the egg or sperm, the dividing parent cell leaves 4 “daughter” cells each holding half the chromosomes (a set of 23 in humans) from the parent cell. Then the organism is capable of sexual reproduction and cycle of new generations can start again. Every time organisms sexually reproduce, half the chromosomes from the mother (egg) and half the chromosomes from the father (sperm) join to create a complete pair of chromosome sets in a new zygote. In humans, a set of 23 chromosomes from the mother and a set of 23 chromosomes from the father join to make a complete pair, totaling 46 (2 sets of) chromosomes in a zygote’s diploid cell. Other animals have their own diploid chromosome numbers, for example, a cat has 60, and an earthworm has 18, corn has 20, and both dogs and chickens have 78.

The organism will continue through life with the genetic information from each parent, one set of chromosomes from the father (23 in humans)



and one set of chromosomes from the mother (23 in humans).

The different combinations of genes made through meiosis provide organisms and their cells with different genetic instructions than their parents, brothers, and sisters. This variation in genes allows different species to acquire different combinations of traits and adapt to changes in their environment. (Refer to previous lessons Home Sweet Home 1 and 2.)

sexual reproduction of Chickens

In sexual reproduction, a new organism forms as a result of fertilization. A male reproductive cell, the sperm, joins a female reproductive cell, the egg. The result is a zygote, which is not a reproductive cell. It develops into a new organism through mitosis, or cell division.

Chickens typically begin to reproduce in the spring, with the onset of longer, warmer days. The rooster, a male chicken over the age of 1, has reproductive organs called testes, which produce sperm. The hen, the female chicken, produces eggs in the form of yolk in her ovaries. It is released into the oviduct, a tube-like part of the hen’s productive system. Both roosters and hens have a hind opening called cloaca. To mate, they rub their cloacas together and sperm is released from the rooster into the hen’s oviduct. Depositing the sperm takes as little as 30 seconds. The sperm travels up the oviduct to join the yolk. The fertilized egg then continues to travel through the oviduct toward the cloaca, essentially making the reverse trip of the sperm. Just before the egg is laid, usually in the morning, a shell is deposited around it.

A fertilized egg still needs to be incubated for about 21 days to develop into a chick.

Hens can lay eggs without a rooster in the coop, but her eggs will be unfertilized and not grow into chicks even though the hen might try to incubate them.

Class meiosis activity

Separate students into groups and assign each group a phase to present to the class using crafts or their own bodies—let them be creative! They can act it out, draw it on the board, or create

some masterpiece on paper, explaining their assigned phase.

Sharing With the Class:

Have each group give a one-minute demonstration to the class, showing how they illustrated their assigned phase of meiosis.

OR have each group draw out each phase and the teacher checks their work as described below:

Provide students with as many of the following art supplies as is practical:

▲s Construction paper

▲s Scissors▲s Glue▲s Tape▲s Modeling clay▲s Pipe cleaners▲s Popsicle sticks

▲s Paint▲s Glitter▲s Yarn▲s Beads▲s Twist ties▲s Markers▲s Tagboard

Then encourage each group to use these supplies in an original way to show how the process of meiosis works. Make sure that they adequately illustrate each phase of meiosis and write a description under each illustration.

Learn more

http://www.brighthub.com/education/k-12/articles/59771.aspx#ixzz1HXgtMgkQ

http://www.youtube.com/watch?v=C6hn3sA0ip0&feature=related

http://www.youtube.com/watch?feature=endscreen&v=JKXAdwCibsA&nR=1



soUrCes

Master Gardener Manual ReferenceArizona Cooperative Extension, College of Agriculture, university of Arizona, Plant Parts and Functions, http://ag.arizona.edu/pubs/garden/mg/botany/plantparts.html

U.s. department of educationhttp://www2.ed.gov/pubs/parents/Science/celery.html

The Complete Book of Science, Grades 5-6American Education Publishing, 2005

Master Gardener Arkansas Handbookuniversity of Arkansas, Division of Agriculture, Cooperative Extension Service, 2001-2002

buzzle.comhttp://www.buzzle.com/articles/how-are-chicken-eggs-fertilized.html

Lecture Notes #1http://www.clt.astate.edu/mhuss/toppage6.htm

science, Level Green2005, The McGraw-Hill Companies, Inc.

Science, See Learning in a whole new lightby Scott Foresman. 2007, Pearson Education, Inc.

Home science Toolshttp://www.hometrainingtools.com/life-cycle-of-a-chicken/a/1482/

meiosis diagramhttp://www.accessexcellence.org/RC/VL/GG/meiosis.php

reproductive cellshttp://www.medterms.com/script/main/art.asp?articlekey=5316

Homologous chromosomeshttp://www.buzzle.com/articles/homologous-chromosomes.html

meiosis activityhttp://www.brighthub.com/education/k-12/articles/59771.aspx

dominant and recessive Characteristicshttp://www.blinn.edu/socialscience/ldthomas/feldman/handouts/0203hand.htm

National Human Genome research Institute http://www.genome.gov/26524120

developmental biology http://www.uic.edu/classes/bios/bios100/labs/develop.htm



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one makes two, and four, …and trillionspart two: cell division and reproduction

Life CyCLes, RepRoduCtion & HeRedity


study guide for studentsduring reproduction, a new organism is made when a male reproductive cell (sperm) fertilizes a female reproductive cell (egg) to create a zygote. The zygote is a fertilized egg that develops into a new organism. The zygote is made up of body cells, so it develops into a mature organism through—you guessed it—mitosis cell division. You learned about mitosis in the last lesson.

Remember that an organism, like you, will divide his or her cells through mitosis so it can grow and regenerate new tissues, like skin tissue after a cut or scratch.

Eventually at a single point of an organism’s life, he or she will divide cells through meiosis. This only happens in the reproductive cells of sexual reproduction organs, the testis or egg, not in the organism’s body cells. For many organisms, this meiosis cell division takes place at maturity.

Regular body cells are diploid cells; this means that they have two sets of chromosomes. In humans, one set is made up of 23 chromosomes. Together, these two sets of 23 make a complete pair of chromosomes (23 + 23 = a complete pair equaling 46 chromosomes total). A diploid cell has just the right number of chromosomes to create new body cells, but these are not the same number for every animal. Other animals have their own diploid cells that contain a different total number of chromosomes. A diploid cell in a human has 46 chromosomes, but a diploid cell in an earthworm has 18, a corn plant has 20, and both dogs and chickens have 78.

It is the job of meiosis to make sure that reproductive cells are not diploid cells, but haploid cells. This means that they make each cell contain only a single set of chromosomes (23 in humans), instead of a pair of sets (46 in humans). This meiosis cell division is important, because it makes sure that organisms get half of their chromosomes (one set) from their mother and the other half (one set) from their father.

Meiosis consists of two steps, meiosis I and meiosis II, and four phases in each step. These phases are called prophase, metaphase, anaphase and telophase, just like during mitosis. However, even though the names are the same, the developments that happen in these four phases during meiosis are not the same as the ones during mitosis. At the end of meiosis, the nucleus has split twice, resulting in four reproductive cells, each containing one-half the number of chromosomes that was in the original nucleus. Only reproductive cells undergo meiosis, not body cells.

Continued next page


Page 2 LIFE CYCLES, REPRODuCTIOn & HEREDITY • One Makes Two…, Part 2: Study Guide

A single parent diploid cell (two homologous chromosome pairs) divides to produce four daughter haploids cells (one homologous chromosome of the pair).

Four phases of meiosis:

Interphase: Before meiosis begins, genetic material is duplicated.

First division of meiosis

Prophase 1: Duplicated chromatin condenses. Each chromosome consists of two, closely associated sister chromatids.

Metaphase 1: Homologous chromosomes align at the equatorial plate.

Anaphase 1: Homologous pairs separate with “sister” chromatids remaining together.

Telophase 1: Two “daughter” cells are formed with each “daughter” containing only one chromosome of the homologous pair.

Second division of meiosis: Gamete formation

Prophase 2: DnA does not replicate.

Metaphase 2: Chromosomes align at the equatorial plate.

Anaphase 2: Centromeres divide and “sister” chromatids migrate separately to each pole.

Telophase 2: Cell division is complete. Four haploid daughter cells are obtained.

Meiosis ensures that reproductive cells contain only single sets of chromosomes. You’ll want to remember these main facts:

▲s One parent cell produces four “daughter” cells.

▲s “Daughter” cells have half the number of chromosomes found in the original parent cell

▲s Meiosis differs from mitosis primarily because there are two cell divisions in meiosis, resulting in cells with a haploid number of chromosomes.

Once meiosis is complete, the dividing parent cell leaves 4 haploid cells each holding half the chromosomes of the organism (23 in humans). now that this organism has created reproductive cells through meiosis, it has the ability to sexually reproduce and the making of a new generation of offspring can start again. Every time organisms sexually reproduce, half the chromosomes from the mother (egg) and half the chromosomes from the father (sperm) join to create a total number of chromosomes in a new zygote. In humans, a set of 23 mother chromosomes join a set of 23 father chromosomes to make a pair, totaling 46 chromosomes in the new zygote.

The organism will continue through life with the genetic information from each parent, one set of chromosomes from the father and one set

the process of meiosis


LIFE CYCLES, REPRODuCTIOn & HEREDITY • One Makes Two…, Part 2: Study Guide Page 3

from the mother. Each set teaming up to form a complete pair of chromosome sets.

a couple more things about meiosis:

Meiosis happens repeatedly in reproductive organs. Sometimes, mistakes happen. They are fairly common in plants and not necessarily harmful. Strawberries, for example, have extra-large fruits because they have more than two sets of chromosomes. Mistakes in animal reproduction are less frequent, but more serious. Organisms with too many or too few chromosomes might not grow normally or not survive very long. Sometimes, the chromosomes are not being copied or divided exactly, leading to mutations. Mutations can be harmful, neutral or beneficial. Mutations can change a species over time.

diploid a cell that contains two sets of chromosomes, one from each parenthaploid a cell that contains a single set of chromosomes, one from one parent.eukaryotic characterized by well-defined cells (with nuclei and cell walls).mitosis the division of a nucleus. Mitosis leads to an exact duplication of the original cell; each nucleus contains the same number and type of chromosomes. Body cells split through mitosis, reproductive cells do not.nucleus the control center of a cell that also contains the genetic material of the cell.chromosomes package of DNA located inside the nucleus of animal and plant cells.homologous chromosomes identical chromosomes in size and gene make-up; these chromosomes pair during meiosis, which needs to occur for the formation of gametes, or reproductive cells.meiosis ensures that reproductive cells contain only single sets of chromosomes, only happens when forming reproductive cells in the egg and sperm.reproductive cells eggs and sperm; each mature reproductive cell is haploid in that it has a single set of 23 chromosomes. (Cells that contain pairs of chromosomes are said to be diploid.) zygote a fertilized egg cell that develops into a new organism through mitosis. centromeres binds two joining chromatids during cell replication.cromatid one of the two side by side replicas produced by chromosome replication; subunit of chromosome after replication and joined at the centromere.DNA (deoxyribonucleic acid) instructions for the design of each living creature that is passed from parents to offspring.interphase the period in which body cells make a copy of their DNA and rest from cell division.


one makes two, part 2Life CyCLes, RepRoduCtion & HeRedity

Aclass

assignment

LS 3.7.1 Explain that the fertilized egg cell carries genetic information from each parent and multiplies to form a complete organism.

1. what type of cells does meiosis produce?

2. How many cells does meiosis produce from one cell?

3. How is meiosis different from mitosis?

4. If an earthworm has 18 chromosomes in a diploid cell, how many chromosomes are in an earthworm haploid cell?

Take it HomePets also benefit from

some exercise. After school today take your dog for a walk;

if you don’t have one, ask a friend if you can tag along

for their daily walk.



Aclass

assignment

answer key

1. what type of cells does meiosis produce? Reproductive cells

2. How many cells does meiosis produce from one cell?Four

3. How is meiosis different from mitosis?Meiosis produces reproductive cells, while mitosis produces body cells.

4. If an earthworm has 18 chromosomes in a diploid cell, how many chromosomes are in an earthworm haploid cell?Nine.



Bclass

assignment


1. what type of cells does meiosis produce?

2. How is meiosis different from mitosis?

3. How does an organism receive genetic information from both parents?







Bclass

assignment

answer key

1. what type of cells does meiosis produce? Reproductive cells

2. How is meiosis different from mitosis?Meiosis produces reproductive cells with a haploid set of chromosomes, while mitosis produces body cells with diploid chromosomes.

3. How does an organism receive genetic information from both parents?Meiosis produces reproductive cells with only half of the hereditary material of body cells. When a male and female reproductive cell join together, they each contribute half of the genetic information to the new organism.



Cclass

assignment


1. How are the products of meiosis different from the products of mitosis?

2. How does an organism receive genetic information from both parents?

3. How is the process of meiosis different from the process of mitosis?

4. what is the difference between dominant and recessive traits?







Cclass

assignment

answer key

1. How are the products of meiosis different from the products of mitosis? Meiosis produces reproductive cells with a haploid set of chromosomes, while mitosis produces body cells with diploid chromosomes.

2. How does an organism receive genetic information from both parents?Meiosis produces reproductive cells with only half of the hereditary material of body cells. When a male and female reproductive cell join together, they each contribute half of the genetic information to the new organism.

3. How is the process of meiosis different from the process of mitosis?Mitosis involves just one cell division, while meiosis has two cell divisions.

4. what is the difference between dominant and recessive traits?Dominant traits mask recessive traits.

Dominant traits are expressed more often than recessive traits.

An organism has to have two copies of a recessive trait for it to be expressed, while it only needs one copy of a dominant trait for that trait to be expressed.

Documents

Y CL, REPRODUCT HRT one makes two, and four, …and trillionsLS 3.7.8 Identify the number and source of chromosomes in human body cells. LS 3.7.10 Explain the role of cell division