Mendelian Classical Genetics Mendel used observations of patterns to establish his understanding of genetics

Terminology

How Mendel’s Observations Relate to a Chromosome

Words that mean aa or AA Homozygous True breeding What do dominant and recessive mean?

Wild-type Each type of geneticist has their own “notation” Drosophila geneticists – Wild-type vs. mutant Does wild type always mean more common?

Fruit flies are cool… How can one gene cause such a dramatic change? Hox genes: Eukaryotic genes that control a series of downstream genes. – What bacterial genes are these analogous to?

Mendel’s 3 Laws Law of Segregation Law of Independent Assortment Law of Dominance

How are all 3 laws displayed here!

Let’s practice a dihybrid cross Aliens: – Skin color: Dominant, purple; Recessive, green – # of eyes: Dominant, 1; Recessive, 3 1)Test cross of a parent that is heterozygous for both genes 2)Test cross of a parent that is homozygous for both genes 3)Cross between two heterozygous parents

Mendel’s Law of Dominance doesn’t always apply…be able to define and give an example of: Incomplete dominance Co-dominance Multiple Alleles Epistasis Pleiotropy Recessive lethal Polygenic Sex-linked

Incomplete Dominance How does the phenotypic ratio change?

Co-Dominance

Multiple Alleles…Blood Type Dominant Alleles: I A and I B Recessive allele: i Allows for Blood Types A, B, O, AB – What genotypes allow for the above phenotypes?

An aside…blood donation

What is rH? Why doesn’t rH incompatibility happen until later pregnancy (use your knowledge of the immune system to explain!)

Epistasis How do the results deviate from a normal cross between two heterozygotes?

Pleiotropy

Recessive Lethal How would this affect the phenotypic ratios expected from a mating between 2 heterozygous individuals? Why is CF considered recessive lethal? Will it always be considered recessive lethal?

Tay Sachs

Is the mutation an insertion or a deletion? Technique: – Exon analysis – What is needed To be able to compare the exons of affected and normal individuals? Why is it important to be able to diagnose a carrier?

Polygenic Most visible genes: eye color (7), skin color (3)

Sex-linked More common in males On X chromosome Muscular dystrophy, Hemophelia, colorblindness DO not confuse with LINKAGE!

Colorblindness Rods Cones

Pedigrees Show genetic traits over many generations – What is this inheritance pattern? – What would an inheritance pattern for autosomal dominant look like? Autosomal recessive?

What is next? Review the problems related to what we discussed today. (Due Wednesday 4/3) Chi-square (Monday) – How can chi-square be used to analyze the results of a genetic cross? Linked genes (Monday and Tuesday) – Recognize when genes are linked. – Use linkage and recombination frequency to calculate map distance. – Practice mapping eukaryotic genes and bacterial plasmids