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Chi- Square analysis

Chi- square statistic used to quantify data and determine whether or not a sample is following simple Mendelian inheritance patterns. (P< 0.05, we reject the null hypothesis (simple mendelian) ; P>0.05 not significant, we accept null hypothesis)

• The P value is the probability of observing your result or something at least as extreme given that your expectation (null model) is correct

Degrees of Freedom- equal to the number of independent variables in an experiment, it will typically be the number of phenotypic classes (n) minus 1.

Why Dominance?

• Genes are regions of DNA that encode a function product- typically a protein

• Alleles are versions of a gene that have differences in the code resulting in different forms if the protein; Alleles can have functional effects due to different protein shapes (full, partial, or no function) or different amounts

• Types of Alleles

  • Null- An allele that produces no functional product

  • Hypomorphic- an allele with function similar to but less than the wild-type allele. Some product may be produced or a small amount of function maintained despite a change in shape

  • Dominant negative- an abnormal product produced by one allele interferes with the overall function of the protein, even if the other is functional

  • Hypermorphic- an allele that results in too much expression of the product- leading to a deleterious effect

  • Neomorphic- the allele changes the function to something different from the wild type

• The type of dominance depends in the specific pair of alleles and what happens when two different versions of the same gene are present in the heterozygote

• Types of Proteins

  • Enzymes are proteins that catalyze a specific biochemical reaction

Example: Snapdragon Colors

• In snapdragons, the ANS gene codes for color→ An1 and An2 are two different versions (alleles) of the ANS gene that determines the phenotype of

  the flower color trait.

• The allele that when homozygous results in the white phenotype is actually a loss of function null allele that results in a completely inactive enzyme.

• Incomplete Dominance: ON

Hypomorphic alleles produces less function proteins and are typically recessive.