What are some of the things you already know about heredity and genetics? (STAR book)

What are some things you want to learn?

Chapter 5.1 Have you ever wondered why some family members look very similar while others look very different?

What were the results of Mendel’s experiments, or crosses? What controls the inheritance of traits in organisms? Section 1: Mendel’s Work

Heredity Is the passing of physical characteristics from parent to offspring.

Trait Each different form of a characteristic is called a trait.

Fertilization The process of a new organism beginning to form due to the joining of a sperm and an egg cell.

Purebred The offspring of many generations that have the same trait.

Hybrid Is an organism that has two different alleles for a different trait.

Hybrid Is an organism that has two different alleles for a different trait.

Genes vs Alleles Genes are the factors that control a trait Alleles are the different forms of a gene

Dominant vs Recessive Alleles Dominant always shows up Recessive is hidden by a dominant allele The only was a recessive allele shows up is if the organism has TWO recessive alleles for a particular trait.

Black is dominant and white is recessive in bunnies

Symbols for Alleles Geneticists use Letters Capital letters are used for dominant alleles Lower case are used for recessive alleles

Crossing Pea Plants Gregor Mendel crossed pea plants that had different traits. The illustrations show how he did this.

Mendel’s Experiments In all of Mendel’s crosses, only one form of the trait appeared in the F 1 generation. However, in the F 2 generation, the “lost” form of the trait always reappeared in about one fourth of the plants.

Dominant and Recessive Alleles Mendel studied several traits in pea plants.

Mendel's final Conclusions Each of the selected garden pea traits is controlled by a pair of alleles (uh-lee-uls)

Mendel's final Conclusions Each of the selected garden pea traits is controlled by a pair of alleles (uh-lee-uls) For each trait, the offspring receives one allele from each parent

Mendel's final Conclusions Each of the selected garden pea traits is controlled by a pair of alleles (uh-lee-uls) For each trait, the offspring receives one allele from each parent The chance of each offspring receiving one or the other allele is equal (50/50 chance)

Mendel's final Conclusions Each of the selected garden pea traits is controlled by a pair of alleles (uh-lee-uls) For each trait, the offspring receives one allele from each parent The chance of each offspring receiving one or the other allele is equal (50/50 chance) The expression of a dominant trait only requires one dominant allele, recessive requires two recessive alleles.

End of Section: Mendel’s Work HW: Please complete the Questions on page 159 (1abc- 2abc) in your STAR book