Section 3 – Studying Heredity Simple Genetics Section 3 – Studying Heredity

Pre-Assessment On a whiteboard with your group: Compare the following pairs and give examples: Dominant & Recessive Homozygous & Heterozygous

Alleles Alleles Alleles: different versions of a trait An individual has two copies of a gene – one from each parent

Alleles Dominant: expressed form of a trait Recessive: form not expressed but present Each gamete contributes one allele to create a two allele offspring

Modern Terms Homozygous Heterozygous When two alleles in a particular gene are displayed as the same Ex: PP or ww Heterozygous When two alleles in a particular gene are displayed differently Ex: Pp or Ww PP = homozygous dominant Ww = homozygous recessive

Mid-Assessment On a whiteboard with your group: Think of ways to remember these opposites: Homozygous & Heterozygous Dominant & Recessive **We will fill out vocabulary

Mid-Assessment Think of ways to remember these opposites: Homozygous & Heterozygous

Mid-Assessment Think of ways to remember these opposites: Dominant & Recessive

Modern Terms Cont. Genotype Phenotype Set of alleles an individual contains for a specific trait Phenotype The physical appearance of a character or trait Pp => purple flower Genotype Phenotype

Post-Assessment In your journal Answer the following questions: Explain how dominant and recessive traits are represented. How many alleles does each offspring receive from each parent and how does this selection happen? (Think back to meiosis) Describe the difference between genotype and phenotype. Using the letters T and t, write the heterozygous and homozygous form.

Pre-Assessment On a whiteboard with your group explain the following: How do siblings from the same mother and same father look similar but not identical?

Recap Dominant - strong or expressed trait Recessive - “weaker” not expressed Genotype - the ‘alleles’ that represent physical features Phenotype - the physical feature

Law of Segregation First Law of Heredity States that – the two alleles of a character segregate (separate) when gametes are formed

Law of Independent Assortment States that – alleles of different genes separate independently of one another during gamete formation

Punnett Squares A diagram that predicts the outcome of a genetic cross by considering all possible combinations Parents Father - on top of Punnett Square Mother - on the side of Punnett Square Each of the boxes inside are filled with 2-4 letters depending the type of cross 2 – monohybrid 4 - dihybrid

Post-Assessment In your journal Answer the following questions: Complete a Punnett Square cross for a father with heterozygous dominant traits (Pp) and homozygous dominant mother (PP). Define the percentage of homozygous dominant possibility Define the percentage of heterozygous dominant possibility Define the percentage of homozygous recessive possibility Answer the same questions as above for two heterozygous dominant parents.