Type of Leopard Gecko Picture Gene

Transcription

“Gecko Breeding Challenge”
A local zoo wants to hire someone to develop plans to breed rare animals. You will take on the role as a breeder
and geneticist so you may win the Zoo’s business, and attract future clients in the exotic animal and pet
industry. Worldwide, the exotic animal trade is a multibillion dollar industry, so you have a great opportunity
to begin your career as a geneticist and breeder.
While you are not an expert at breeding geckos, you are confident that you can develop a successful plan
because you already have some ideas about how traits are passed on from parents to children and you believe
you can learn what you don’t know. The geckos that you can breed are shown below.
Type of
Leopard Gecko
Picture
Gene
Normal
N/A
Albino
Albino
Blizzard
Blizzard
Patternless
Mack Snow
________________________
Patternless
Mack
Super Mack Snow
Mack
Enigma
Enigma
Giant
Looks like Normal, but bigger.
Giant
Male: 90-109g in first year of life
Female: 80-89g in first year of life
Supergiant
Male: More than 110g at 1 year old
Female: More than 90g at 1 year old
Weights for all geckos other than Giant and Supergiant: Male: 70-90g (as adult) Female: 50-70g (as adult)
Background Research
After researching the principles of genetics, you have found the following information to assist with your
breeding efforts. Genes are segments of DNA that determine an individual’s traits or phenotype. Each one of these
genes has different version called an allele. For example, the trait of eye color comes in different varieties like brown,
green, and blue because individuals have different allele, versions of the gene. Since meiosis splits up pairs (homologous)
of chromosomes, each parent passes on one copy of each gene. Consequently an individual has two copies of every gene,
one from mom (maternal) and one from dad (paternal). The genotype or combination of alleles for an individual
determines their phenotype or traits. The two alleles for a trait can interact in different ways. If an allele covers up
another version of the gene, its considered dominant and represented with a capital letter. So whenever an individual
possesses a dominant allele, he or she will have the dominant phenotype trait . Recessive alleles are represented by
lower case letters, and the recessive phenotype (trait) is hidden when an individual also has a dominant allele. For a
given trait, if an individual has two different alleles the genotype is heterozygous (ex. Gg, Tt, Ee, Ff). If an individual
has two of the same alleles the genotype is homozygous (ex. GG, gg, TT, tt, FF, ff).
In a paragraph, describe which Geckos you plan to breed in order to produce a rare type of Gecko unlike any pictured
above. Explain your reasoning.
“Inheritance Rules”
To begin you breed a blizzard male with a normal female and get the results below.
Male Blizzard Parent
Female Normal Parent
Mated with…
All Normal Offspring
Produced…
As with the cross above, you cannot always easily predict the outcome of a cross, just considering the phenotypes of the
parents. Use pictures A and B below to help understand the process of inheritance.
Describe how offspring are generated based on picture A.
Picture A
Describe how picture B illustrates each of the three inheritance rules. If you prefer, you can write or draw on the
picture to show where you think each of the rules is depicted.
a. Each organism has two copies (alleles) of each gene.
b. Each organism gets one allele from the male parent and one allele from the female parent.
c. Offspring can only inherit the alleles that are present in the parents.
Picture B
STUDENT WORKSHEET MASTERS “Inheritance Simulation”
Often, as scientists and engineers, it is helpful to test predictions in some way before time and money are
invested in a full-blown solution or a major experiment. Sometimes, it is better to do those tests using a
simulation that is based on scientific knowledge. As a class, you will design a simulation that can be used now
to test your predictions about 1gene and later on to test your predictions as you work with more genes. You will
work in pairs to do this activity.
Designing the Simulation Activity:
Remember to keep in mind the inheritance rules you wrote and the information in the fertilization pictures (A
and B) to help you justify the steps in the simulation.
Procedure for Simulation Activity: Inheritance through Generation of Offspring
The procedure may be very simple, but in order to use this procedure again for more than one gene, you need to
write down the steps precisely.
Resources available to you:
Pictures A and B
Inheritance Rules
The activity materials
Two paper geckos (one male and one female)
Two bags of shapes (one for each gecko)
Two bags of gametes (A gamete is a generic term for egg and sperm: eggs for the female gecko and
sperm for the male gecko)
The activity designer has chosen to represent different types of genes with different shapes and to represent the
different alleles for each gene with different colors. To figure out what you have been given: Each person
should take one of the bags of shapes, and making sure to keep the contents of the bags separate, dump the
contents on the desk and answer the questions below.
a. How many different types of shapes do you have? Therefore how many different genes do you have?
b. How many different colors do you have? Therefore how many different alleles do you have?
c. What is the genotype of parent 1? What is the genotype of parent 2?
d. Why do you think you have multiple squares of each color and multiple eggs or sperm?
e. How does this relate to either Picture A or B about how offspring are formed?
Making the Prediction
Write down the cross that is being performed in this simulation activity:
a. If these parents were to have 16 offspring, write down the different allele combinations you would
expect to see and how many offspring will have each allele combination.
Allele Combinations
Number of Offspring with that Allele Combintion
Name
Understanding Inheritance
Teacher
Date
Task D: Developing a Model of Inheritance for One Gene
Task D3: Worksheet 4b: Connecting the process of inheritance with the outcomes
Part I: Procedure for Putting Alleles in Eggs and Sperm
4) Write down the step(s) you will take to put alleles in eggs and sperm.
STEP
JUSTIFICATION
(Inheritance Rule or Information from Picture A or B)
5) Follow that step for all the gametes (eggs or sperm) you have.
a. Fill out the Eggs and Sperm Table to show what types of eggs and what types of sperm
your geckos will produce:
EGGS
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Name
Teacher
Date
Part II: Procedure for Making Offspring Now that you have instructions for generating eggs and
sperm. 6) Write down the step(s) you will take to make offspring from the eggs and sperm.
STEP
JUSTIFICATION
7) Follow that step for all the eggs and sperm you have.
a. Write down the allele combinations you saw in the offspring.
Evaluating Your Predictions
b. Were your predictions about the types of allele combinations expected in the
offspring supported by the simulation or not? How do you know?
c. Were your predictions about the number of offspring with each allele combination
supported by the simulation? Why or why not?
1. What difficulty with your thinking caused your predictions to be inaccurate
when you made them?
2. What have you learned that will help you make better predictions in the
future?
(Aren’t you glad you didn’t have to wait for the geckos to breed and hatch and invest in PCR
before you found out whether your predictions were accurate?!)
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Name
Teacher
Date
8) Now, predict the results of this cross:  X 
Egg and Sperm Table:
EGGS
Predictions Pedigree:
SPERM

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
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STUDENT WORKSHEET MASTERS Name_______________________________Teacher______________________Date_________
Task D5: Worksheet 4e : Application of One Gene Model
1) Suppose you are a genetic counselor (a professional who helps couples identify and discuss
the probability of having children with inherited disorders). The couple shown below has come
to see you: They are interested in having children, but are concerned about the possibility of one
being born with cystic fibrosis. Cystic fibrosis is a disease that causes mucus to build up in the
lungs and other areas of the body, and results in a shortened life span. The genotype for a person
with cystic fibrosis is while healthy children are either  or .
a. In the space above, complete the prediction pedigree to show possible offspring
genotypes as well as the proportions of offspring genotypes. Support your answer
with an egg & sperm table (below) and your math equation.
EGGS
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Name_______________________________Teacher______________________Date_________
b. The couple tells you they are expecting their first child. What is the
chance/probability that this child will be a healthy heterozygote?
Explain how you know.
c. What is the chance/probability this child will have cystic fibrosis?
Explain how you know.
d. The couple returns to your office a few years later along with their healthy first
child, and tell you they are expecting their second child. Does the chance/probability
of having cystic fibrosis change for this second child? Explain to the couple why or
why not.
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Name_______________________________Teacher______________________Date_________
2) Humans have three possible alleles for the gene that determines blood type, shown below:
Using this information and the outcomes pedigree below, answer the questions below.
a. What is the genotype of person 2c? Explain how you know using the inheritance rules.
b. What are the possible genotypes for 1c? Explain your answer using inheritance rules.
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Connecting Pedigrees to the Gecko Design Challenge
Apply your knowledge of pedigrees to the breeding of Geckos by predicting the outcome of the
crosses below.
A blizzard genotype is , and normal genotypes are either or .
Suppose you now perform the following crosses:
1) X 



2) X 


a. Which cross is more likely to give you a blizzard gecko? Show your reasoning using a math
equation and/or pedigree.
b. Is getting a blizzard a rare event from either mating? Explain why or why not.
c. Revisit your original design plan, on the first page of the Gecko challenge.
-What knowledge do you have now, that will help you design a rare Gecko?
-Modify your plan if needed to produce a rare Gecko.
-What information or resources do you still need to breed a rare Gecko for the zoo?
STUDENT WORKSHEET MASTERS Name
Teacher
Date
Task E: Extending the Model of Inheritance to Multiple Genes
Task E1: Worksheet 5a: Extending the Simulation Activity to Two Genes
When you tried to apply the results of your 1 gene simulation activity to the design challenge,
you realized that in order for the gecko to be rare, it would need to have more than one trait.
Therefore, you need to extend your model of inheritance to include more genes. In order to
help you do this, you are going to extend each of your tools (simulation activity, pedigree,
egg/sperm chart, mathematical equation) to two genes to see what changes, if any, need to be
made. You are going to start as you did in one gene with the simulation activity.
Remember, you have the following resources available to you:
a. Pictures A and B
b. Inheritance Rules
c. Model of Inheritance for One Gene
d. The activity materials
1. Two paper geckos (one male and one female)
2. Two bags of shapes (one for each gecko)
3. Two bags of gametes (A gamete is a generic term for egg and sperm:
eggs for the female gecko and sperm for the male gecko)
Before You Start: Making sense of the simulation materials
1) Circle the zoom level(s) you are working at.
DNA
Gene 1
Allele 1
Allele 1
Gene 2
Allele 2
Allele 2
2) Each person should take one bag of shapes and keeping them separate dump them
out on the desk.
a. What is the genotype of parent 1?
What is the genotype of
parent 2?
b. How are different genes represented? How do you know?
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Name
Teacher
Date
c. How are different alleles for each gene represented? How do you know?
Making the Prediction
3) Write down the cross that is being performed in this simulation activity:
a. If these parents were to have 16 offspring, write down the different allele
combinations you would expect to see and how many offspring will have each allele
combination.
Allele Combinations
Number of Offspring with that Allele Combination
Part I: Procedure for Putting Alleles in Eggs and Sperm
4) Write down the step(s) you will take to put alleles in eggs and sperm.
STEP
JUSTIFICATION
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Name
Teacher
Date
5) Follow that step for all the gametes (eggs or sperm) you have.
a. Fill out the Eggs and Sperm Table to show what types of eggs and what types of sperm
your geckos will produce:
EGGS
SPERM
Summary of Class Discussion
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Name
Teacher
Date
Evaluation of your prediction
6) Write down the allele combinations you saw in the offspring.
a. Were your predictions about the types of allele combinations expected in the offspring
supported by the simulation or not? How do you know?
b. Were your predictions about the number of offspring with each allele combination
supported by the simulation? Why or why not?
i. What difficulty with your thinking caused your predictions to be inaccurate when you
made them?
ii. What have you learned that will help you make better predictions in the future?
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STUDENT WORKSHEET MASTERS Name_______________________________Teacher________________Date________
Understanding
Inheritance of Flower Color
1) Let’s look at plants to extend our examination of how alleles control the traits of an organism.
Sweet Peas
Crossed with…
Produces…
Female (Red)
Offspring (Red)
Male (White)
Crossed with…
Produces…
Snap Dragons
Crossed with…
Produces…
Female (Red)
Male (White)
Offspring (Pink)
Inheritance of Flower Color
Review the flower crosses on the previous pages. Test out the guidelines you have developed and your
understanding of genetics by predicting the genotypes and phenotypes of the offspring between a cross of two
heterozygotes for each type of flowrt. Show your predictions using a pedigree. Don’t forget to show the
proportions of each genotype and phenotype.
Camellia
Sweet Pea
Snap Dragon
Name_______________________________Teacher______________________Date____________
TASK F: Refining the Multigene Model by Connecting Genotype to Phenotype
Task F2: Worksheet 6b: Applying the multi-gene model
2) Below is an outcomes pedigree showing the genotypes of a variety of mustard plant. Plants often
produce many offspring. The following pedigree shows the outcomes of a cross that produced 200
offspring. The colors represent the phenotype of the plants; square alleles code for stem color and
circle alleles code for leaf color. For example, plant 1a has a purple stem with yellow leaves. A
pictorial representation of the plants is shown here:
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a. Which allele is dominant and which is recessive for each gene? Explain how you know.
b. On the diagram above, complete the pedigree for the cross between 2d and 2e, showing the
genotypes, phenotypes, and expected proportions for the offspring.
3) Scientists often use letters, instead of symbols, to represent alleles because it is faster than
drawing symbols. The standard way of doing this is to select the first letter of the dominant trait and
capitalize it; the recessive allele is the same letter but non-capitalized. For example, a gene for plant
height could be represented as T (tall; dominant allele) and t (short; recessive allele).
a. Using the conventions discussed above, write the letter that represents the allele in the table
below.
Gene (Symbol)
Square
Square
Circle
Circle
Allele (Symbol Color)
Black
White
White
Black
Color
Purple stems
Dark green stems
Light green leaves
Yellow leaves
Allele Letter
b. Write the genotype of the double heterozygous offspring from the cross between 2d and 2e using
only letters. What proportion do you expect of this type and why? Support your answer using an
equation and/or an egg and sperm table.
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4) Suppose you want to breed a blizzard gecko that has six toes. You know that the blizzard allele is
recessive to the normal allele for color, and that the allele for six toes is dominant to the allele for the
normal number of toes. (Note: Always assume simple dominance unless otherwise specified). Using
either symbols or letters:
a. Write the genotype(s) for a blizzard 6-toed gecko.
b. Write the genotype(s) for a blizzard gecko.
c. Write the genotype(s) for a normal gecko.
d. Name one cross that would produce a blizzard 6-toed gecko. Support your work with a
pedigree, egg and sperm table, or equation.
5) You want to perform the following cross:  X 
a. How many allele combinations are there in the offspring? Show how you figured this out.
b. What proportion of the offspring will you expect to be triple homozygous black
()? Show how you figured this out.
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c. If the question in 5b had asked, “What is the probability that an offspring will be triple
homozygous black?” would your answer from above change? Why or why not?
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“Gecko Breeding Challenge Final Design”
With an understanding of genetics and inheritance you will design your final breeding plan to produce a rare
Gecko. You will present your breeding plan to produce the rare geckos on a poster. You can choose three
Geckos to purchase from the list below. The poster will contain the following information:
1. Your Names/Teacher’s Name/Date
2. An introductory paragraph which contains the following information:
a. What type of gecko you are planning to breed and why.
b. A 3-5 sentence summary of your plan for obtaining that gecko.
3. Which geckos you will buy initially and why.
4. For each cross that you make, you will include the following information.
a. The geckos you are planning to mate.
b. The verbal/biological rationale for doing that cross.
c. The mathematical rationale for doing that cross. (This should include a prediction of the types
and amounts of offspring.) Show your work!
5. For crosses which involve fewer than three genes, pictorial representation consisting of a sperm/egg
table and a prediction pedigree showing both genotypes and phenotypes.
4. A summary paragraph for why the zoo should select your group. Your argument should be supported by
EVIDENCE from the poster presentation of the breeding plan.”
*Note that each of the six genes is separate. The genotype listed applies for all six genes. So a homozygous
Albino lizard is homozygous for the Albino gene and normal homozygous for all other genes.
Type of
Leopard
Gecko
Picture
Gene
Recessive or Homozygous or
Dominant
Heterozygous
Normal
N/A
N/A
Homozygous or
Heterozygous (for
any other trait of
interest)
Albino
Albino
Recessive
Homozygous
Blizzard
Blizzard
Recessive
Homozygous
Patternless
Patternless
Recessive
Homozygous
Mack Snow
Mack
Codominant
Heterozygous
Super Mack Snow
Mack
Codominant
Homozygous
Enigma
Enigma
Dominant
Homozygous or
Heterozygous
Giant
Giant
Codominant
Heterozygous
Male: 90-109g in first year of life
Female: 80-89g in first year of life
Supergiant
Codominant
Homozygous
Male: More than 110g at 1 year old
Female: More than 90g at 1 year old
Weights for all geckos other than Giant and Supergiant: Male: 70-90g (as adult) Female: 50-70g (as adult)

Type of Leopard Gecko Picture Gene

Transcription

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