1 Review What did Mendel conclude determines inheritance Explain What are dominant and recessive alleles Apply Concepts Why were true breeding pea plants important for Mendel’s experiments 2 Review What is segregation Explain What happens to alleles between the P generation and the F2 generation

Ch 11 Introduction to Genetics 11.1 The Work of Gregor Mendel

Heredity Genetics Delivery of characteristics from parent to offspring Scientific study of heredity.

The Experiments of Gregor Mendel Founded modern science of genetics Austrian monk Charge of the monastery garden.

The Experiments of Gregor Mendel Worked with pea plants Multiple generations each growing season Many traits Traits in one of two forms Easy to grow Lots of offspring.

The Role of Fertilization Stamen Male part of each flower makes pollen (contains sperm) Carpel Female portion of each flower produces reproductive cells called eggs.

Fertilization Male and female reproductive cells join For peas tiny embryo encased within a seed Peas normally are self pollinating Sperm and egg are from same parent.

True-breeding or Pure Breeding Trait Specific characteristic of an individual, such as seed color or plant height May vary from one individual to another True-breeding or Pure Breeding Produce offspring with identical traits to themselves.

He cut away the pollen-bearing male parts and then dusted on the pollen from a different flower.

Hybrid Offspring of crosses between parents with different traits.

Generations P1- original parents F1- first offspring, F is for filial F2- second generation of offspring; F1’s kids.

Mendel’s Two Conclusions Individual’s characteristics are determined by factors that are passed from one parental generation to the next These factors come in two varieties Principle of dominance Some alleles are dominant and will cover up the recessive version of the allele.

Genes Alleles Factors that are passed from parent to offspring Different forms of the gene.

Dominant Version of trait that shows up in each generation of Mendel’s experiments Can hide the other form of that trait Capital letter Recessive Version that was covered up in the F1 generation Lower case letter.

Tall plant is dominant over short.

Where Did the Recessive Gene Go Mendel allowed all seven kinds of F1 hybrids to self-pollinate He found recessive trait in about ¼ of the F2 generation.

Segregation Gamete Alleles split and each gamete only carries one Sex cells (egg or sperm).

Dominant allele had masked the corresponding recessive allele in the F1 generation.

F1 plants were tall with a tall allele from one parent and a short allele from the other parent.

F1 adults produces gametes, the alleles for each gene segregate from one another.

Whenever two t’s combine, a short plant results Whenever there is even one T, a tall plant results.