Interest Grabber Section 11 1 Analyzing Inheritance Offspring

Interest Grabber Section 11 -1 Analyzing Inheritance Offspring resemble their parents. Offspring inherit genes for characteristics from their parents. To learn about inheritance, scientists have experimented with breeding various plants and animals. In each experiment shown in the table on the next slide, two pea plants with different characteristics were bred. Then, the offspring produced were bred to produce a second generation of offspring. Consider the data and answer the questions that follow. Go to Section:

Interest Grabber continued Section 11 -1 Parents First Generation Second Generation Long stems short stems All long 787 long: 277 short Red flowers white flowers All red 705 red: 224 white Green pods yellow pods All green 428 green: 152 yellow Round seeds wrinkled seeds All round 5474 round: 1850 wrinkled Yellow seeds green seeds 6022 yellow: 2001 green All yellow 1. In the first generation of each experiment, how do the characteristics of the offspring compare to the parents’ characteristics? 2. How do the characteristics of the second generation compare to the characteristics of the first generation? Go to Section:

Section Outline Section 11 -1 11– 1 The Work of Gregor Mendel A. Gregor Mendel’s Peas B. Genes and Dominance C. Segregation 1. The F 1 Cross 2. Explaining the F 1 Cross Go to Section:

Principles of Dominance Section 11 -1 P Generation Tall Go to Section: Short F 1 Generation Tall F 2 Generation Tall Short

Section 11 -1 Seed Shape Seed Color Round Yellow Figure 11 -3 Mendel’s Seven F 1 Crosses on Pea Plants Seed Coat Color Gray Pod Shape Pod Color Flower Position Smooth Green Axial Tall Short Wrinkled Green White Constricted Yellow Terminal Round Yellow Gray Smooth Green Axial Go to Section: Plant Height Tall

Interest Grabber Section 11 -2 Tossing Coins If you toss a coin, what is the probability of getting heads? Tails? If you toss a coin 10 times, how many heads and how many tails would you expect to get? Working with a partner, have one person toss a coin ten times while the other person tallies the results on a sheet of paper. Then, switch tasks to produce a separate tally of the second set of 10 tosses. Go to Section:

Interest Grabber continued Section 11 -2 1. Assuming that you expect 5 heads and 5 tails in 10 tosses, how do the results of your tosses compare? How about the results of your partner’s tosses? How close was each set of results to what was expected? 2. Add your results to those of your partner to produce a total of 20 tosses. Assuming that you expect 10 heads and 10 tails in 20 tosses, how close are these results to what was expected? 3. If you compiled the results for the whole class, what results would you expect? 4. How do the expected results differ from the observed results? Go to Section:

Section Outline Section 11 -2 11– 2 Probability and Punnett Squares A. B. C. D. Go to Section: Genetics and Probability Punnett Squares Probability and Segregation Probabilities Predict Averages

Tt X Tt Cross Section 11 -2 Go to Section:

Interest Grabber Section 11 -3 Height in Humans Height in pea plants is controlled by one of two alleles; the allele for a tall plant is the dominant allele, while the allele for a short plant is the recessive one. What about people? Are the factors that determine height more complicated in humans? Go to Section:

Interest Grabber continued Section 11 -3 1. Make a list of 10 adults whom you know. Next to the name of each adult, write his or her approximate height in feet and inches. 2. What can you observe about the heights of the ten people? 3. Do you think height in humans is controlled by 2 alleles, as it is in pea plants? Explain your answer. Go to Section:

Section Outline Section 11 -3 11– 3 Exploring Mendelian Genetics A. Independent Assortment 1. The Two-Factor Cross: F 1 2. The Two-Factor Cross: F 2 B. A Summary of Mendel’s Principles C. Beyond Dominant and Recessive Alleles 1. Incomplete Dominance 2. Codominance 3. Multiple Alleles 4. Polygenic Traits D. Applying Mendel’s Principles E. Genetics and the Environment Go to Section:

Concept Map Section 11 -3 Gregor Mendel experimented with Pea plants concluded that “Factors” determine traits Some alleles are dominant, and some alleles are recessive which is called the Law of Dominance Go to Section: Alleles are separated during gamete formation which is called the Law of Segregation

Figure 11 -10 Independent Assortment in Peas Section 11 -3 Go to Section:

Figure 11 -11 Incomplete Dominance in Four O’Clock Flowers Section 11 -3 Go to Section:

Interest Grabber Section 11 -4 How Many Chromosomes? Normal human body cells each contain 46 chromosomes. The cell division process that body cells undergo is called mitosis and produces daughter cells that are virtually identical to the parent cell. Working with a partner, discuss and answer the questions that follow. Go to Section:

Interest Grabber continued Section 11 -4 1. How many chromosomes would a sperm or an egg contain if either one resulted from the process of mitosis? 2. If a sperm containing 46 chromosomes fused with an egg containing 46 chromosomes, how many chromosomes would the resulting fertilized egg contain? Do you think this would create any problems in the developing embryo? 3. In order to produce a fertilized egg with the appropriate number of chromosomes (46), how many chromosomes should each sperm and egg have? Go to Section:

Section Outline Section 11 -4 11– 4 Meiosis A. Chromosome Number B. Phases of Meiosis 1. Meiosis I 2. Meiosis II C. Gamete Formation D. Comparing Mitosis and Meiosis Go to Section:

Crossing-Over Section 11 -4 Go to Section:

Figure 11 -15 Meiosis Section 11 -4 Meiosis I Go to Section:

Figure 11 -17 Meiosis II Section 11 -4 Meiosis II Prophase II Metaphase II Anaphase II Meiosis I results in two The chromosomes line up in a The sister chromatids haploid (N) daughter cells, similar way to the metaphase separate and move toward each with half the number of stage of mitosis. opposite ends of the cell. chromosomes as the original. Go to Section: Telophase II Meiosis II results in four haploid (N) daughter cells.

Interest Grabber Section 11 -5 Forever Linked? Some genes appear to be inherited together, or “linked. ” If two genes are found on the same chromosome, does it mean they are linked forever? Study the diagram, which shows four genes labeled A–E and a–e, and then answer the questions on the next slide. Go to Section:

Interest Grabber continued Section 11 -5 1. In how many places can crossing over result in genes A and b being on the same chromosome? 2. In how many places can crossing over result in genes A and c being on the same chromosome? Genes A and e? 3. How does the distance between two genes on a chromosome affect the chances that crossing over will recombine those genes? Go to Section:

Section Outline Section 11 -5 11– 5 Linkage and Gene Maps A. Gene Linkage B. Gene Maps Go to Section:

Comparative Scale of a Gene Map Section 11 -5 Mapping of Earth’s Features Mapping of Cells, Chromosomes, and Genes Cell Earth Country Chromosome State Chromosome fragment City People Go to Section: Gene Nucleotide base pairs

Figure 11 -19 Gene Map of the Fruit Fly Section 11 -5 Exact location on chromosomes Go to Section: Chromosome 2

Videos Click a hyperlink to choose a video. Meiosis Overview Animal Cell Meiosis, Part 1 Animal Cell Meiosis, Part 2 Segregation of Chromosomes Crossing Over

Video 1 Meiosis Overview Click the image to play the video segment.

Video 2 Animal Cell Meiosis, Part 1 Click the image to play the video segment.

Video 3 Animal Cell Meiosis, Part 2 Click the image to play the video segment.

Video 4 Segregation of Chromosomes Click the image to play the video segment.

Video 5 Crossing Over Click the image to play the video segment.

Go Online The latest discoveries in genetics Interactive test Articles on genetics For links on Punnett squares, go to www. Sci. Links. org and enter the Web Code as follows: cbn-4112. For links on Mendelian genetics, go to www. Sci. Links. org and enter the Web Code as follows: cbn-4113. For links on meiosis, go to www. Sci. Links. org and enter the Web Code as follows: cbn-4114.

Interest Grabber Answers 1. In the first generation of each experiment, how do the characteristics of the offspring compare to the parents’ characteristics? All offspring had the same characteristic, which was like one of the parents’. The other characteristic seemed to have disappeared. 2. How do the characteristics of the second generation compare to the characteristics of the first generation? Both characteristics appeared in this generation. The characteristic that had “disappeared” in the first generation did not appear as often as the other characteristic. (It appears about 25 percent of the time. )

Interest Grabber Answers 1. Assuming that you expect 5 heads and 5 tails in 10 tosses, how do the results of your tosses compare? How about the results of your partner’s tosses? How close was each set of results to what was expected? Results will vary, but should be close to 5 heads and 5 tails. 2. Add your results to those of your partner to produce a total of 20 tosses. Assuming that you expect 10 heads and 10 tails in 20 tosses, how close are these results to what was expected? The results for 20 tosses may be closer to the predicted 10 heads and 10 tails. 3. If you compiled the results for the whole class, what results would you expect? The results for the entire class should be even closer to the number predicted by the rules of probability. 4. How do the expected results differ from the observed results? The observed results are usually slightly different from the expected results.

Interest Grabber Answers 1. Make a list of 10 adults whom you know. Next to the name of each adult, write his or her approximate height in feet and inches. Check students’ answers to make sure they are realistic. 2. What can you observe about the heights of the ten people? Students should notice that there is a range of heights in humans. 3. Do you think height in humans is controlled by 2 alleles, as it is in pea plants? Explain your answer. No, height does not seem to be controlled by two alleles, as it is in pea plants. Height in humans can vary greatly and is not just found in tall and short phenotypes.

Interest Grabber Answers 1. How many chromosomes would a sperm or an egg contain if either one resulted from the process of mitosis? 46 chromosomes 2. If a sperm containing 46 chromosomes fused with an egg containing 46 chromosomes, how many chromosomes would the resulting fertilized egg contain? Do you think this would create any problems in the developing embryo? 46 + 46 = 92; a developing embryo would not survive if it contained 92 chromosomes. 3. In order to produce a fertilized egg with the appropriate number of chromosomes (46), how many chromosomes should each sperm and egg have? Sperm and egg should each have 23 chromosomes.

Interest Grabber Answers 1. In how many places can crossing over result in genes A and b being on the same chromosome? One (between A and B) 2. In how many places can crossing over result in genes A and c being on the same chromosome? Genes A and e? Two (between A and B and A and C); Four (between A and B, A and C, A and D, and A and E) 3. How does the distance between two genes on a chromosome affect the chances that crossing over will recombine those genes? The farther apart the genes are, the more likely they are to be recombined through crossing over.

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