EQ: How do genotypes affect phenotypes? Gregor Mendel EQ: How do genotypes affect phenotypes?

Vocab Heredity: passing of physical characteristics from parents to offspring Trait: each different form of a characteristic (height, eye color) Genetics: the scientific study of heredity

Look at be picture of the mother and baby cats below. What can you infer the father cat looks like?

Until the work of Gregor Mendel, people did not understand how traits were passed from parent to child. Mendel wondered why pea plants had different characteristics. Some were tall, others were short. Some plants produced green seeds, and others had yellow seeds. Mendel observed that the traits were often similar to their parents, but sometimes they were different.

The pistol produces female sex cells, or eggs. The stamens produce pollen, or male sex cells. Fertilization is the process of an egg and a sperm joining to make a new organism. Plants usually self- pollinate, but Mendel developed cross- pollination.

The experiment... Mendel crossed two contrasting purebred pea plants (a tall and a short) Purebred: offspring of many generations that have the same trait

Experiment 1: The F1 offspring Mendel crossed purebred tall plants with purebred short plants…. This is the parent generation, or P generation The offspring would be the F1 generation. Result…. All of the pea plants were tall!

Experiment 2: The F2 offspring Mendel allowed the F1 generation pea plants self-pollinate. The plants in the F2 generation were a mix of tall and short plants! About ¾ of the plants were tall, and ¼ were short.

Dominant and Recessive Alleles The factors that control each trait exist in pairs…. One from the female and one from the male. One factor in each trait can mask, or hide, the other.

Vocab Gene: factors that control a trait Alleles: different forms of a gene Dominant allele: one whose trait always shows up when the allele is present Recessive allele: only shows up when a dominant allele is not present

Difference between Gene and Allele Gene Examples: Height, Hair color, Eye Color Allele Examples: Tall or Short, Blonde or Red hair, Blue or Brown eyes

Types of Genes Heterozygous: Both alleles are different Example: Brown eye color – Bb Homozygous: Both alleles are the same Example: Brown eye color or not – BB or bb

Punnet Squares We use these to decide how genotypes affect phenotypes Genotype: What your gene (allele) combination is Phenotype: What your physical appearance is. (people with different genotypes can have the same phenotype.)