| Introduction to Genetics |
| Activity #1 A Smorgasbord of Ears and Other Traits Please read the section (pg. 152-153) A. What are alleles? B. What does it mean that one allele is dominant and another allele is recessive? C. How do Tom Cruise and Charles Barkley differ from Gregory Mendel and Joan Chen? D. Do you have detached ear lobes? Activity #2 Mendel�s Background (Text pg. 154-155) A. How did people a century ago think that traits were passed down from one generation to the next? B. Why is the �blending theory� not a good theory? C. Explain Charles Darwin�s theory of natural selection. D. What was Mendel the first to accomplish? E. Where did Mendel come from? F. What kind of plants did Mendel work with? Why do you suppose he worked with those particular plants? Activity #3 Mendel�s Pea Plants If you took seeds from tall plants and planted them, what would you get? Tall plants, right? RIGHT! While seeds from short plants would always grow short plants, right? RIGHT! Now if you fertilized the flowers of each type of plant with the pollen from the other type (cross-pollination) what would you expect the offspring to be? Some short and some tall or maybe all middle-sized? WRONG! They would ALL turn out tall! If these plants were allowed to pollinate themselves, what would their offspring turn out to be? Probably all tall again right? WRONG! Copy down on your notebook�. (drawings from Mr. Liao) B. 1. Label the cross of the first 2 plants with the letter �P� then Generation for (parental cross). 2. Label first offspring with an �F1� for first filial (children) generation. 3. Label the next Generation with �F2� for second filial (grandchildren) generation. Activity #4 Mendel�s Theory of Segregation A. (Text pg. 156) What was Mendel�s big idea about segregation? B. (Figure 10-4, pg. 156) This is an example of Mendel�s mono-hybrid crosses. Notice the chromosomes from the purple cell? Homozygous dominant parent. Notice the chromosomes from the light blue cell? Homozygous recessive parent. Follow the chromosomes as they are duplicated and split into the gametes. Fertilization produces heterozygous offspring. Heterozygous where an individual has a pair of non-identical alleles (Aa). C. What did Mendel think about fertilization as being a chance event? D. Take a look at all the mono-hybrid crosses performed by Mendel (pg. 156 Figure 10.5) 1. Give me 3 dominant traits of pea plants. 2. Give me 3 recessive traits of pea plants. 3. There is something really particular about the ratios of the F2 generation of all of these crosses. Can you figure it out? |