Ms. McKinley


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Antibiotic Resistance:
Case Study



UNIT 6: Heredity

What you should know:

There are different versions of genes called alleles. Individuals usually have two alleles for a gene, each inherited from a different parent. Individuals with the same two alleles for a gene are homozygous, while individuals with two different alleles for a gene are heterozygous. The law of segregation states that the two alleles for a trait separate when gametes are formed. The law of independent assortment states that two or more pairs of alleles separate independently of one another during gamete formation.

Punnett squares are used to predict the results of genetic crosses and to find probabilities for phenotypes and genotypes. A test cross can be used to determine whether an individual expressing a dominant trait is heterozygous or homozygous. The pattern of inheritance of a trait can be analyzed using a pedigree. Traits usually have complex patterns of inheritance such as incomplete dominance, codominance, and multiple alleles.

Mutations can cause genetic disorders such as sickle cell anemia. Genetic disorders can be passed down from generation to generation. Punnett squares can be useful in finding the probability that your child will be born with your genetic disorder if your genotype and your partner's genotypes are known.

How you make sense of things:

Initial EPE before lab

Observations you make
in your daily life:

Patterns you notice:
Explanations for the patterns:

Some of your traits look like your mom's and some look like your dad's.

You look similar to your family members in some ways.

When you go to the doctor they may ask you if anyone in your family has certain genetic diseases like anemia or cancer.

You may have the same genetic disorders, like diabetes or anemia, as your family members.

You get chromosomes from each parent, which causes you to have similar features and genetic disorders as your parents or grandparents.


Goal EPE after lab

Observations you make
during lab:

Patterns you notice
in the data:
Explanations for the patterns:

Inventory of Traits
Observation that you have a dominant phenotype for some traits and a recessive phenotype for others.

Calculations of the frequency of certain traits in our class.

Kitty Project
Observation of cat pictures showing the phenotype of the cat.

Determination of the cat's genotype for several traits based on the cat's phenotype.

Pedigree Analysis
Observation of which individuals have a trait in the pedigree.

Inventory of Traits
Dominant traits are more frequent in our class and in the general populaton than recessive traits.

Kitty Project
Several alleles are responsible for the color of a cat's coat.

Pedigree Analysis
Determination of the pattern of inheritance of the trait represented by the pedigree - several possibilities: autosomal, sex-linked, recessive, or dominant.

Inventory of Traits
Dominant alleles are expressed when both dominant and recessive alleles are present.

Kitty Project
Multiple alleles can affect the same trait.

Pedigree Analysis
Pedigree analysis can be used to determine the pattern of inheritance of particular traits in your family.


What you should be able to do:

1. Explain that the information passed from parents to offspring is transmitted by means of genes that are coded in DNA molecules. These genes contain the information for the production of proteins.
2. Differentiate between dominant, recessive, codominant, polygenic, and sex-linked traits.
3. Explain the genetic basis for Mendel's laws of segregation and independent assortment.
4. Determine the genotype and phenotype of monohybrid crosses using a Punnett Square.