Download Jody Rosnik - ED591geneticslesson

Lesson Plan for Wiki ED591 by Jody Rosnik
Title: How to make a chocolate rabbit
Grade: 5th/6th
Subject: Science
Topic of Study: Genetics
Colorado Model Content Area:
Science
Standard 3: Life Science: Students know and understand the characteristics and
structure of living things, the processes of life, and how living things interact with each other and
their environment. (Focus: Biology)
Benchmark/Grade Level Expectancy: Grades 6-8 #10 a. Chromosomes and genes play
a role in heredity (for example, genes control traits, while chromosomes are made up of many
genes).
3.10b. Infer the traits of the offspring based on the genes of the parents (including dominant,
recessive traits and use of Punnett square diagrams).
Math
Standard 1: Students develop number sense and use numbers and number relationships
in problem-solving situations and communicate the reasoning in solving these problems.
Benchmarks/grade Level Expectancy: Grades 5-8 #3 and 4: Apply number theory
concepts to represent numbers in various ways. Use the relationships among fractions, decimals,
and percents, include the concepts of ratio and proportion, in problem solving situations.
Information Literacy
Standard 3: The information literate student uses information accurately and creatively.
Benchmarks/indicators 1. Organizes information for practical application. 2. Integrates
new information into one's own knowledge. 3. Applies information in critical thinking and
problem solving. 4. Produces and communicates information and ideas in appropriate formats.
Standard 9: The information literate student contributes positively to the learning
community and to society and participates effectively in groups to pursue and generate
information.
Benchmarks/indicators: 1. Shares knowledge and information with others. 2. Respects
others' ideas and backgrounds and acknowledges their contributions. 3. Collaborates with
others, both in person and through technologies, to identify information problems and to seek
their solutions. 4. Collaborates with others, both in person and through technologies, to design,
develop, and evaluate information products and solutions.
Lesson Objectives: Students will recognize a multiple allele trait and use phenotype to
determine the genotype of a selected coat color of a domestic rabbit. Students will infer the coat
color and probabilities on a cross of two different colored rabbits using a Punnett Square.
Assessment Plan:
Informal Assessment: With information given throughout the lesson the wiki-lesson
students will complete a fill in the blank paragraph to show comprehension and review basic
genetics terms. Students will post discussion questions if they need help or have any other
information to share.
Performance Assessment: At the end of the video demonstration, students will be
choosing a coat color to demonstrate how to generate and identify its possible genotype with the
information learned.
Summative Assessment: Students will complete Punnett squares with at least one and
two gene locations to determine probabilities of coat colors of offspring and a second generation.
Materials:
Computer or other device with Internet connection to access the lesson wiki
Time Allotment: 1 week to complete the 3 assessments from first signing-in to the wiki
address.
Learning Context and prior knowledge:
Rabbit colors, just like other traits (size, fur structures, eye color, toenail color, and hundreds of
others) are inherited from the rabbit's parents: called the Sire and Dam.
As you recall from previous lessons, the whole body is made up of cells, whether it is a
human body or an animal body. The nucleus (center) of every cell (muscle, blood, skin, hair,
etc…) contains all the information that determines the genotype of the rabbit. The genotype is
similar to a set of instructions with every necessary ingredient, or materials needed, to construct
that being: it's just like a recipe so we can say the recipe is carried in the genes, which are
certain spots on the chromosomes, in the nucleus of each cell.
Chromosomes are in pairs, so genes are also in pairs. Rabbits have 22 pairs of
chromosomes. Each chromosome has lots and lots of genes-hundreds, maybe thousands. Every
cell of every part of the rabbit has 22 pairs of chromosomes. The only exceptions are certain
blood cells, and the sex cells—the egg and sperm—they have half pairs, or just 22 single
chromosomes. When a male rabbit (buck) and a female rabbit (doe) are mated, the buck
provides the sperm cell, with 22 single chromosomes, to combine with an egg cell from the doe,
with 22 single chromosomes to make 22 pairs for the first cell of the developing new bunny.
The baby bunny gets half of each of its chromosome pairs from the sire (father) and half from the
dam (mother). SO, since the genes are on the chromosomes, it's getting half of it's genes from
the sire and half from the dam.
Out of the thousands of genes in a rabbit, the major genes for colors have been identified
by scientists. There are 5 major color genes that have been given convenient words that describe
each major gene, and each is assigned a capital letter that serves as a 'code' for the gene.
Write on board:
A for agouti pattern
B for black
C for having color
D for density of color
E for extension of color along the hair shaft.
Very rarely, a gene changes, or mutates, for some unknown reason, and it will take a different
form. Another form of a gene is called an allele. A rabbit with a mutated gene can pass this new
allele to its offspring. The scientists have identified recessive alleles of the 5 dominant color
genes (A, B, C, D, E) and have given them lower-case letters to serve as their genetic codes (a, b,
c, d, e).
Since every bunny inherits half of each gene pair from its sire and half from its dam, it might
inherit an original gene form (capital letter) from one parent, but a different form of the same
gene (lower-case letter) from the other parent.
Capital letter codes for the dominant genes and they dominate; what they say goes! Even when
there is one dominant gene and one recessive gene in a gene pair, the color will be what the
dominant gene says. This is the dominant/recessive relationship.
Using the Punnett Square:
To illustrate the combining of chromosomes scientists use a model called the Punnett
Square. We can see through the use of a punnet square why there is a 50/50 chance of producing
either sex of bunny (this works the same in all animal genetics, including humans): when rabbits
are mated, the following are the possible X and Y chromosomes combinations that can occur:
we must know that every normal male is XY and every normal female is XX. (Who then, is it
that determines the sex of the children/offspring?)
Here are the rules to completing a punnet square: Sire's chromosomes are listed to the
left, on the vertical line, the dam's chromosomes are listed above on the horizontal line. The 4
squares represent the possible combinations which could be born. Each bunny of this mating
must have one of these combinations. Each of these has an equal probability of occurring.
Therefore, of four babies, 2 should be does and two should be bucks or 2:2 ratio which can be
reduced to a 1:1 ratio which is also a 50/50 chance. But, in the nest box this does not always
work this way, this is because we are not dealing with certainties, but with probabilities, which
only hold true for very large populations (maybe with a sample size as large as 100 we may get
very close to equal numbers of bucks and does. You will most likely learn and study more of
this in a statistics class in High School)
Coat color genes can be determined in just the same way. Instead of just 2 chromosome
pair for the sex, there are 5 gene pairs that deal with coat colors.
The color genes are listed in their rank-order of dominance within each location: For
example, Agouti (AA) is dominant over Black Otter tan pattern (at a), but tan pattern is dominant
over the solid self pattern (aa). The following list is complete, but in this lesson we are only
concerned with the A and B series.
A- Color pattern Genes
A =Agouti (banded) hair shaft with lighter pattern on eye circle, nostril, nape of neck
(triangle), belly, underside of tail, inside ear.
at =Tan pattern with main body area a solid color and a lighter color in the typical
Agouti pattern areas.
aa =solid self color, non-banded.
B-Color Pigment Genes
B =Black color.
bb =brown (chocolate) recessive color
C- Amount of pigment produced in the hair shaft
C =Full color (necessary for any yellow/orange/red color to show)
chd =Removes most of the red, leaving pearl-white color.
chl =Lightens the black, producing a dark brown shading effect
ch =Californian white body, dark extremities, pink eyes (restricted albino)
cc =lack of color. Albino.
D- Distribution of pigment
D =Normal dense undiluted color
dd =Diluted color also changes eye color from brown to gray
E- Extension of black pigment (Tipping color at end of hair shaft)
E =Normal extension of dark pigment to the tip of the hair shaft.
Es= Steel tipping
ej =Japanese brindling in mosaic harlequin pattern
ee =Eliminates most dark pigment, exposing the underlying red if the dominant full
color gene (C) is present.
How these Colors look: Phenotype vs Genotype:
Agouti Group: A_
Chestnut/Castor/Copper
Chocolate chestnut/Amber
Opal
Lynx
Chinchilla (Blue Chinchilla, Chocolate Chinchilla, Lilac Chinchilla, Sable Chinchilla,
Smoke Pearl Chinchilla)
Tan Pattern: at_
Otter
Martins
Solid: aa
Black: B_
Blue: B_dd
Chocolate: bb
Lilac: bbdd
REW: cc
Shaded group
Sable: chd chd
Sable points: chl chl
Tortoises
Pointed White/Himalayan/Californian : chch
Wide Band Group
Red
Orange
Fawn
Cream
Steel
Punnett Squares for Color
Punnett Squares are a convenient way of listing all the possible gene combinations for any cross.
They can be complicated if your parent rabbits have many different alleles, and a Punnett square
can get out of hand, so if you don't need to know all the possibilities but only want to know the
probability of one color we can combine each gene pair separately which only takes the 2 x 2
square.
Procedure:
Opening:
Welcome and objectives.
Body: Watching the videos/powerpoints of the lesson and the video demonstrating the changing of
alleles. Look at the color pictures labeled with the phenotypes (you will use these for assessment #2 so
find one that you like).
Assessments
1. The Basic genetics terms page is to be completed by filling in the blanks and posting to the
discussion page.
2. 1 example demonstration for #2 will be included on the wiki page as a video. Instruct the
students to refer to the gene descriptions above to help with this:
Have the students go back to the colors display pages and find their favorite color of
rabbit. Tell them to type in their favorite color (phenotype) in the appropriate blank on their
quiz. Have them try to produce the genotype for the phenotype. Collaboration between students
can be helpful for this part.
3. Punnet Squares. Students can complete these anyway they choose, but must be posted to the
discussion.
Science Processes used:
Observing: looking at actual coat colors, noticing patterns.
Classifying: Seeing how the color groups are related to each other by association of
allele combinations.
Communicating: Ample time throughout the lesson is given for questions and answers
and students comparing notes.
Predicting: When reviewing Punnett squares, a pre guess of what possible color
combinations are given, as well as the reason for using a Punnett square to determine the
probability of a specific coat color.
Inferring: Being able to infer is part of the benchmark for this lesson (3.10b).
Differentiation of Instruction:
To provide for the needs of diverse learners I will use various strategies of instruction:
For the visual learners, the word bank in the opening is used as well as the display of live
rabbits to show the coat colors that are represented in the lesson; for the auditory learners, the
lesson is given verbally as a direct lesson, and questions can be verbally posted to the wiki by the
students; The introduction to multiple alleles is scaffolding for most of the students in 5th and
6th grade. To be able to work on the phenotype/genotype question on the quiz with other
classmates helps to build a community of learners for the class.
Extension Activities:
1. Add to the above lesson:
Advanced--Modifiers
In addition to the 5 color genes, there are many modifying factors that can have a great affect on
the resulting coat color. These minor genes are called modifiers because they do not produce a
color by themselves, but rather they influence color development by their cumulative effects.
Some lighten or darken the color, some can turn yellow into deep red, some bring stray white
hairs and white toenails. The broken pattern in rabbit coat colors is the heterozygous spot pattern
modifier. The dominant En spotting gene produces the desired markings only when it's inherited
in the heterozygous form, Enen. The homozygous dominant genotype, EnEn, is a Charlie
which is mostly white with a few scattered colored spots. The homozygous recessive genotype,
enen, is found in the normal coloration of every other variety. Therefore, the only way to
produce a Broken is when at least one parent is a Broken (or a REW which is masking a Broken
pattern genotype _ _ _ cc _ _Enen)
Charlie to Charlie (EnEn X EnEn) = 100% light spotted Charlies
Charlie to Broken (EnEn X Enen) = 50% Broken and 50% Charlies
Charlie to Colored (EnEn X enen) = 100% Brokens
Broken to Broken (Enen X Enen) = 25% Charlies, 50% Brokens, 25% fully colored
Broken to Colored (Enen X enen) = 50% Broken, 50% fully Colored
Colored to Colored (enen X enen) = 100% fully colored
2. Relate multiple allele genes to other traits in animals such as size, breed, mutations in fur,
etc…
Acknowledgment of Some References Used:
4-H Manual Leaps and Bounds. Rabbit 3. St. Paul: Minnesota Extension Service, 1993.
Haenszel, Candy. Color Genetics in the U.S. Domestic Rabbits. 2003.
Mason, Tom. "Coat Color Genetics". The Wooly Guide. Sloan's Printing Services, 1993.
Schott, Bobby. Color Genetics of the Netherland Dwarf Rabbit. Douglasville: Xavier
Reference Publishing, 1989.
Arrington, L.R., and K.C. Domestic Rabbit Biology and Production. Gainsville: University
Presses of Florida, 1976.