Predicting Inheritance Mendelian genetics

Genetics Vocabulary Gregor Mendel First person to successfully predict how traits are transferred from one generation to the next. Used pea plants to show how genes were passed down The “father of genetics.”

Genetics Vocabulary Homozygous/Purebred: Two alleles for a trait are the same Examples: RR, rr, FF, qq, mm Heterozygous/Hybrid: Two alleles for a trait are different Examples: Rr, Ff, Qq, Mm

Heterozygous or Homozygous? TT Pp dd Ff Tt FF

Heterozygous or Homozygous? TT- homozygous Pp- heterozygous Dd- homozygous Ff- heterozygous Tt- heterozygous FF- homozygous

Rule of Unit Factors Alleles: expressions of a gene; carried in gametes Each organism has two alleles that control each of its traits, one from father and one from mother. Example: PP, Pp, pp Never: P, p, Ppp, PPp

Genotype versus Phenotype Genotype: Individual’s genes Gen- Produce Birth Origin Phenotype: Individual’s physical appearance Pheno- Appear

Rule of Dominance Only one trait is observed. The observed trait is called dominant and the trait that disappeared is called recessive. Example: →

Rule of Dominance In Squidward’s family, a blue body color (B) is dominant to green (b). Determine the phenotype for each genotype below based on this information. BB Bb bb

Rule of Dominance In Squidward’s family, a blue body color (B) is dominant to green (b). Determine the phenotype for each genotype below based on this information. BB- blue Bb-blue bb- green

Law of Segregation Every individual has two alleles for each gene. Each gamete receives one of these alleles. During fertilization, these gametes randomly pair to produce four combinations of alleles. Example: →

Law of Independent Assortment Genes for different traits are inherited independently of each other. Example: seed shape (round or wrinkled) and seed color (green or yellow)

Review What is the name for an individual with two of the same alleles? What is the name for an individual with two different alleles? What is the name of the trait that disappears? The name of the trait that is observed? How many alleles for each trait does an organism have?

Answers to the Review What is the name for an individual with two of the same alleles? Homozygous What is the name for an individual with two different alleles? Heterozygous What is the name of the trait that disappears? Recessive The name of the trait that is observed? Dominant How many alleles for each trait does an organism have? Two

Let’s put this into action! SpongeBob is known for his big round eyes (R), which are dominant over an oval eye shape (r). If he is heterozygous for his round eye shape and marries a woman with oval eye shape, what type of eyes might his kids have? Step 1: List the genotypes of the parents: Heterozygous round eyes: ____ Oval eyes: ____

Step 2: Punnett Square Heterozygous round eyes: Rr Oval eyes: rr

R r r r Step 3: Punnett Square Heterozygous round eyes: Rr Oval eyes: rr R r r r

Rr rr rr Rr R r r r Step 4: Punnett Square Heterozygous round eyes: Rr Oval eyes: rr R r Rr rr r rr Rr r

Predictions & Ratios Based on the results of the Punnett Square, identify the possible offspring combinations. % Homozygous round eyes (RR) ___________ % Heterozygous round eyes (Rr) ___________ % Homozygous oval eyes (rr)___________

Predictions & Ratios Based on the results of the Punnett Square, identify the possible offspring combinations. Homozygous round eyes (RR) _0%_________ Heterozygous round eyes (Rr) ___50%______ Homozygous oval eyes (rr)__50%_________

Now you try one on your own. If two heterozygous round seed pea plants (Rr) are crossed, what percentage of offspring will be homozygous recessive? Use a Punnett square to find the answer.