Ch. 4-1 Mendel’s Work Key Concepts: What were the results of Mendel’s experiments, or crosses?

1. Ch. 4-1 Mendel’s WorkKey Concepts: What were the results of Mendel’s experiments, or crosses? Discover Activity: What Does the Father Look Like? • Observe the colors of the kitten’s coat colors and patterns. • Record any coat colors and patterns that you observe. Include as many details as you can. • ______________________________________________________________ • ______________________________________________________________ • 2. Observe the mother cat, record her coat color and pattern. • ______________________________________________________________ • ______________________________________________________________ • 3. Infer: Describe what you think the kitten’s father might look like. Identify the evidence on which you based your inference. • ______________________________________________________________ • ______________________________________________________________ • ______________________________________________________________

2. http://www.youtube.com/watch?v=5Rylcijkp9c&feature=related

3. Mendel’s Experiments Key Terms: Heredity: The passing of physical characteristics from parents to offspring Trait: Characteristic that an organism can pass on to its offspring Genetics: The scientific study of heredity For Mendel’s Experiment he “cross-pollinated” pea plants with contrasting traits. For example: short and tall plants Mendel started with purebred plants.

4. Mendel’s Experiments The F1 Offspring: In one experiment, Mendel crossed purebred tall plants with purebred short plants. These plants were known as the parental generation (p generation). Their offspring are the first filial generation (F1 generation) Result: All the offspring in the F1 generation were tall. The F2 Offspring: In the next test when the F1 generation plants were full-grown Mendel self-pollinated the plants. Result: The short trait reappeared. The F2 generation was a mix of tall and short plants. P Generation F1 Generation F2 Generation

5. Mendel’s Conclusions Mendel crossed pea plants with other contrasting traits. In all of Mendel’s crosses, only one form of the trait appeared in the F1 generation. However, in the F2 generation, the “lost” trait reappeared in one fourth of the plants. • What did Mendel find when he crossed purebred tall plants with purebred short plants • ________________________ • ________________________ • When Mendel crossed the F1 Generation with one another was the trait for shortness lost? • _________________________ • 3. Are the plants in the F1 generation purebred plants? • _________________________

6. Dominant and Recessive Alleles The purple corn ears were produced by the F2 generation. The purple color is produced by the dominant allele, and yellow is controlled by the recessive allele. Gene: factors that control a trait Alleles: different forms of a gene An organism’s traits are controlled by the alleles it inherits from its parents. Some alleles are dominant, while other alleles are recessive. Dominant Allele: one whose trait always shows up in the organism when the allele is present Recessive Allele: trait that is hidden whenever a dominant allele is present. P = Purple p = Yellow Trace back the inheritance of the dominant and recessive alleles for kernel color. F2 generation: both purple ___________ F1 parents: both purple ___________ P parents: one purple ____________ one yellow ___________

7. Predicting In fruit flies, long wings are dominant over short wings. A scientist crossed a purebred long-winged male fruit fly with a short-winged female. Predict the wing length of the F1 offspring. If the scientist crossed a hybrid male F1 fruit fly with a hybrid F1 female, what would their offspring probably be like? Long Winged = L Short Winged = l

8. Mendel’s Experiments Key Term: Symbols for Alleles Geneticists use letters to represent alleles. Dominant represented by capital letter. Recessive represented by lowercase of same letter. Hybrid: Organism that has two different alleles for a trait Example: Chapter 4 Section 1 Assessment On a separate piece of paper answer: Page 115 Questions 1 and 2