Review for Genetics - A (use problem sets too!)
Chapter 9. Fundamentals of Genetics (your handout with “example problems” is part of the review)
1. Be able to describe and use the following vocabulary easily:
a. Characteristic, trait, self-pollination, cross-pollination, true breeding, P F1 and F2
generations, dominant, recessive, allele, gamete, offspring, progeny, heterozygous,
homozygous, test cross, dihybrid, monohybrid, genotype, phenotype. Be able to
identify bolded terms as they relate to Punnett squares, probability
T o show me this, write a paragraph about the following Punnett squares
A. A Fire breathing dragon mates with a non-fire breathing dragon. Fire breathing = F and nonfirebreathing = f. They have four dragon babies over the years, 3 are non fire-breathing and
one is fire-breathing.
B. A secondary characteristic is number of toes. All of the babies have three toes, but Dad has only
2 toes and Mom has four toes.
Write a story about the dragons. Create a Punnett square for each characteristic and indicate genotypes
and phenotypes of parents and babies. Use ALL the vocabulary. Make this good, because this
assignment will be graded as a part of your test. This must be completed before review day .
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Review for Genetics - A (use problem sets too!)
2. Identify the purpose and “set up” of a test cross.
3. List and differentiate between the Laws of Dominance, Segregation and Independent
assortment. What type of inheritance pattern do these refer to? What does each mean
4. How do current day molecular genetics support Mendel’s conclusions? Based on his laws, what
were Mendels three conclusions? Does present day molecular biology support his Laws?
Explain which inheritance patterns support his claims and which do not.
5. What are three things we know now, that Mendel did not know?
What inheritance patterns do we now know?
6. Explain why the Punnett square does not tell you what each of your four children would be but
is simply a visual that shows the random assortment and recombination of genes during meiosis
and fertilization
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Review for Genetics - A (use problem sets too!)
7. Be able to model (identify parents, and inheritance patterns and use a Punnett square) and
predict outcomes for monohybrid (single gene) word problems using Punnett squares and
“word explanations”. For dominant/recessive, codominant, or incompletely dominant patterns
(see your problem sets)
8. Incompletely dominant patterns and codominance patterns are sometimes shown using the
notations and problem setup provided in class Bb (incomplete); CwCB (codominant) and XAXA (sex
linked), multiple alleles (ABO blood group or any other problem that involves ONE gene but 3 or
more alleles). Choose a problem from your problem sets and for each scenario and recopy it
into your review sheet.
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Review for Genetics - A (use problem sets too!)
Predict the phenotypic and genotypic outcomes of a dihybrid test cross (two non-linked genes) using
Punnett squares AND mathematical methods (small Punnett squares and multiplying).
a. How many alleles does each gamete show in the Punnett square
b. How do you create “all possible combinations” for the gametes and the zygotes
(offspring).
c. Determining genotype vs. phenotype ratios for two traits.
Create a Punnett square that shows the cross between two Blue (B) and Horned (H) fish The mother is
heterozygous for both traits, while the father is homozygous recessive for both traits. The recessive
alleles are White (b) and No Horn (h).
Parent genotype father____________
Mother _______________
Parent phenotypes: father___________
Mother_________________
Possible gametes for father:______________________ for mother ________________________
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Review for Genetics - A (use problem sets too!)
Chapter 12. You will be tested on the information found in the questions below:
1. What is a sex-linked trait? On which sex chromosome are almost all sex-linked traits found?
2. Many sex-linked genes exhibit a disease condition from a recessive allele much more frequently
in males (as compared to females). Why would X-linked diseases show up more in men? Explain
in terms of the possible alleles from the mother and the father.
3. How can genes on the same chromosome (linked genes) become “unlinked”?
Pedigree questions are mostly from your notes
4.
A pedigree is a diagram of family relationships that uses symbols to represent people and lines
to represent genetic relationships. These diagrams make it easier to visualize relationships
within families, particularly large extended families. Pedigrees are often used to determine the
mode of inheritance (dominant, recessive, etc.) of genetic diseases. Use your pedigree handout
to answer the following:
a.
b.
c.
d.
How do you indicate a person that has a disease on a pedigree?
How might you indicate a carrier
What shape represents female
What shape represents male?
5. (5-8not in the book). How do you determine by looking at a pedigree, whether a disease due to
an autosomal recessive allele?
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Review for Genetics - A (use problem sets too!)
6. When a pedigree shows an autosomal dominant disease, what key inheritance patterns do you
see in the pedigree?
7. When a pedigree shows an X-linked disease, what key inheritance patterns do you see in the
pedigree?
8. What is a polygenic characteristic? What is an example of a polygenic characteristic? What
distribution does a polygenic characteristic typically show?
9. What is a multiple allele characteristic? What differentiates it from a polygenic characteristic?
What is an example of a multiple allele characteristic?
a. What are the three possible alleles (be sure to use the proper notation) for human blood
type?
b. Which alleles show codominance?
c. Which allele is recessive to the other two?
d. What are all possible genotypes and phenotypes of the ABO gene?
10. Some families have a “baldness” allele that is X-linked. Is it possible for a female offspring to
show this phenotype? Create a Punnett square that provides evidence to support your answer.
11. What is a genetic counselor and what do they do?
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