Download One Makes Two - Arkansas GardenCorps

Life Cycles,
Reproduction & Heredity
one makes two,
and four, …and trillions
part two: cell division and reproduction
Frameworks
SCIENCE
LS 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 ARTS
OV.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 Objectives
The 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.
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
Page 2
Life Cycles, Reproduction & Heredity • One Makes Two…, Part 2: Teachers’ Guide
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Overview
All 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
▲▲ Collecting eggs
▲▲ Plant, harvest and work in the garden following the
Garden Guide
▲▲ Recipes and taste tests as time permits (refer to
Delta Garden Study Recipe Book)
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
Life Cycles, Reproduction & Heredity • One Makes Two…, Part 2: Teachers’ Guide
Tips for THE CLASSROOM
Page 3
classroom
Pre-lesson preparation:
1. Determine how the “Chromosome Structure” visual will
be used and prepare appropriately.
materials needed
▲▲ Student Workbooks
▲▲ Materials needed for the
optional class activity
LESSON OUTLINE
in the
classroom
activities
estimated duration actual duration
▲▲ Offer the icebreaker
5 minutes
▲▲ Explain the difference between body
cells and reproductive cells
▲▲ Explain meiosis, define diploid and
haploid
5 minutes
10 minutes
in the garden
▲▲ Observe chickens, collect eggs.
5 minutes
Explain sexual reproduction of
chickens.
▲▲ Plant, harvest and work in the garden 15 minutes
following the Garden Guide
back in the
classroom
▲▲ Hand out Student Learning
Workbooks, review and assign “Take
it Home Activity” as homework
Tips for THE GARDEN
5 minutes
garden
Pre-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.
materials needed
▲▲ Appropriate tools for garden
activities
2. Prepare materials for chicken tending activities.
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Page 4
Life Cycles, Reproduction & Heredity • One Makes Two…, Part 2: Teachers’ Guide
Lesson PLAN
I. Start in the classroom
A.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
▲▲ Revisit the difference between body cells and reproductive
cells and their functions.
▲▲ 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 Objective #1
Meets ObjectiveS
#2–5
II. Take class to the garden
▲▲ Instruct students to gather eggs and observe chickens. Explain
reproduction of chickens.
▲▲ Plant, harvest and work in the garden following the Garden Guide.
Meets ObjectiveS
#1–4
▲▲ Taste available produce. Ask students for feedback.
III.Take class back to classroom
▲▲ Hand out the Student Learning Workbook as reference material
and class assignment. Review take it home activities and encourage
students to do them.
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
Meets Objective #6
Life Cycles, Reproduction & Heredity • One Makes Two…, Part 2: Teachers’ Guide
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.
Page 5
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:
▲▲ One parent cell produces four “daughter”
cells.
▲▲ “Daughter” cells have half the number of
chromosomes found in the original
parent cell.
▲▲ 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)
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Life Cycles, Reproduction & Heredity • One Makes Two…, Part 2: Teachers’ Guide
and one set of chromosomes from the mother
(23 in humans).
some masterpiece on paper, explaining their
assigned phase.
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.)
Sharing With the Class:
Sexual Reproduction of Chickens
Provide students with as many of the following
art supplies as is practical:
▲▲ Paint
▲▲ Construction
paper
▲▲ Glitter
▲▲ Scissors
▲▲ Yarn
▲▲ Glue
▲▲ Beads
▲▲ Tape
▲▲ Twist ties
▲▲ Modeling clay
▲▲ Markers
▲▲ Pipe cleaners
▲▲ Tagboard
▲▲ Popsicle sticks
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
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
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:
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=endscre
en&v=JKXAdwCibsA&NR=1
Life Cycles, Reproduction & Heredity • One Makes Two…, Part 2: Teachers’ Guide
Page 7
Sources
Master Gardener Manual Reference
Arizona 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 Education
http://www2.ed.gov/pubs/parents/Science/celery.html
The Complete Book of Science, Grades 5-6
American Education Publishing, 2005
Master Gardener Arkansas Handbook
University of Arkansas, Division of Agriculture, Cooperative Extension Service, 2001-2002
Buzzle.com
http://www.buzzle.com/articles/how-are-chicken-eggs-fertilized.html
Lecture Notes #1
http://www.clt.astate.edu/mhuss/toppage6.htm
Science, Level Green
2005, The McGraw-Hill Companies, Inc.
Science, See Learning in a whole new light
by Scott Foresman. 2007, Pearson Education, Inc.
Home Science Tools
http://www.hometrainingtools.com/life-cycle-of-a-chicken/a/1482/
Meiosis diagram
http://www.accessexcellence.org/RC/VL/GG/meiosis.php
Reproductive cells
http://www.medterms.com/script/main/art.asp?articlekey=5316
Homologous chromosomes
http://www.buzzle.com/articles/homologous-chromosomes.html
Meiosis activity
http://www.brighthub.com/education/k-12/articles/59771.aspx
Dominant and Recessive Characteristics
http://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
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
Meiosis
Life Cycles, Reproduction & Heredity • One Makes Two…, Part 2: Teachers’ Guide
Chromosome
Structure
Page 8
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
Life Cycles,
Reproduction & Heredity
one makes two,
and four, …and trillions
part two: cell division and reproduction
study guide for students
During 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
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
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.
the process of meiosis
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
Meiosis ensures that reproductive cells contain
only single sets of chromosomes.You’ll want to
remember these main facts:
▲▲ One parent cell produces four “daughter”
cells.
▲▲ “Daughter” cells have half the number of
chromosomes found in the original
parent cell
▲▲ 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
Life Cycles, Reproduction & Heredity • One Makes Two…, Part 2: Study Guide
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 extralarge 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.
Page 3
diploid a cell that contains two sets of
chromosomes, one from each parent
haploid 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.
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
class
assignment
A
Life Cycles, Reproduction & Heredity
one makes two, part 2
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?
Take it Home
3. How is meiosis different from mitosis?
Pets 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.
4. If an earthworm has 18 chromosomes in a diploid cell, how many
chromosomes are in an earthworm haploid cell?
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
class
assignment
A
Life Cycles, Reproduction & Heredity
one makes two, part 2
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.
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
class
assignment
B
Life Cycles, Reproduction & Heredity
one makes two, part 2
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?
Take it Home
2. How is meiosis different from mitosis?
Pets 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.
3. How does an organism receive genetic information from both parents?
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
class
assignment
B
Life Cycles, Reproduction & Heredity
one makes two, part 2
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.
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
class
assignment
C
Life Cycles, Reproduction & Heredity
one makes two, part 2
LS 3.7.1 Explain that the fertilized egg cell carries genetic information from each parent and multiplies to
form a complete organism.
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?
Take it Home
4.What is the difference between dominant and
recessive traits?
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.
Pets 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.
class
assignment
C
Life Cycles, Reproduction & Heredity
one makes two, part 2
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.
ACHRI/DGS/KFK/062812/V1 DRAFT COPY • ©2012 Delta Garden Study.