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Answer the following questions to the best of your ability.

Answer the following questions to the best of your ability. • What is genetics? • How do sexually reproducing organisms obtain different traits? • Who is Gregor Mendel?. Important!!!.

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Answer the following questions to the best of your ability.

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  1. Answer the following questions to the best of your ability. •What is genetics? • How do sexually reproducing organisms obtain different traits? • Who is Gregor Mendel?

  2. Important!!! • Knowing your vocabulary is especially important in genetics. The better you know the vocabulary in this unit, the easier it will be.

  3. GENETICSHeredity- Passing characteristics from parent to offspring.Genetics- The scientific study of heredity. Gregor Mendel Austrian monk known as the father of genetics. Studied pea plants and changed biology forever. Usually pea plants self pollinate (pollinate themselves). He found that when he cross pollinated (crossing sex cells of different plants) plants with different characteristics he got some interesting results.

  4. Parents Long stems  short stems Red flowers  white flowers Green pods  yellow pods Round seeds  wrinkled seeds Yellow seeds  green seeds First Generation All long All red All green All round All yellow Second Generation 787 long: 277 short 705 red: 224 white 428 green: 152 yellow 5474 round: 1850 wrinkled 6022 yellow: 2001 green Interest Grabber continued Section 11-1 • 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?

  5. Principles of Dominance Section 11-1 P1 Generation F1 Generation F2 Generation Tall Short Tall Tall Tall Tall Tall Short

  6. Important Genetics Vocabulary • Trait- Specific characteristics such as seed color or plant height. • Dominant-masks a recessive trait • Recessive-masked by dominant trait • Genes- Chemical “factors” that determine traits. • Alleles- Different forms of a gene. Capital letter represents a dominant allele. Lowercase letter represents recessive allele. • Trait- Height (you can see it) • Gene- Tt (you cannot see it) • Alleles- T-dominant for tallness; t-recessive for shortness (make up genes) • Alleles-> Gene-> Trait

  7. More important vocabulary… • Purebred- Offspring from two parents with like traits • Hybrid- Offspring of crosses between two parents with different traits. • Gametes- Sex cells; reproductive cells • e.g. Humans- male sperm; female egg • Flowers- male pollen; female egg

  8. Interest Grabber Section 11-2 Probability- the likelihood that a particular event will occur.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.

  9. 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. If you compiled the results for the whole class, what results would you expect? 3. How do the expected results differ from the observed results?

  10. Section Outline Section 11-2 • Coin Toss • Expected Results- • Observed Results- • Note: Alleles have a 50/50 chance of being selected.

  11. Punnett Squares • Punnett Square- A diagram used to determine gene combinations from a genetic cross. • Homozygous- same type of alleles (TT; tt) • Heterozygous- different type of alleles (Tt) • Phenotype- physical characteristics (tall, short, round, wrinkled) • Genotype- genetic makeup ( TT, Tt, tt, RR, Rr, rr)

  12. Tt X Tt Cross Monohybrid Cross Section 11-2

  13. Tt X Tt Cross Section 11-2

  14. Interest Grabber Section 11-3 • Pause for Punnett Square Practice

  15. Punnett Square Practice

  16. Alleles are separated during gamete formation. One allele from each parent. “Factors”(genes) determine traits Some alleles are dominant, and some alleles are recessive Pea plants Law of Dominance Law of Segregation Concept Map Section 11-3 Gregor Mendel concluded that experimented with which is called the which is called the

  17. New vocabulary words… • Incomplete Dominance-when neither trait is completely dominant over the other; e.g. white flowers crossed with red flowers may produce pink flowers • Codominance- both alleles contribute to the phenotype; both alleles are dominant; e.g. speckled looking chickens have black and white feathers which are both dominant • Multiple alleles- when genes have more than one allele; e.g fur color in rabbits (four different alleles) or blood type in humans • Polygenic traits- traits determined by more than one gene; skin color in humans

  18. Figure 11-11 Incomplete Dominance in Four O’Clock Flowers Section 11-3

  19. Figure 11-11 Incomplete Dominance in Four O’Clock Flowers Section 11-3

  20. 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

  21. Mitosis vs. Meiosis • Mitosis-● dealing with somatic cells like liver cells, skin cells, and hair cells. • ● cell splits once • ● end up with 2 diploid daughter cells • Meiosis- ●dealing with gametes (reproductive cells) • ● 2 divisions of cells • ● end up with 4 haploid daughter cells

  22. Figure 11-15 Meiosis Section 11-4 Meiosis I

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

  24. Crossing-Over Section 11-4

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

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

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

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

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

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

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

  32. Interest Grabber Answers Section 1 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.)

  33. 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. Section 2 Answers

  34. Interest Grabber Answers Section 3 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.

  35. Interest Grabber Answers Section 4 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.

  36. Interest Grabber Answers Section 5 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.

  37. End of Custom Shows • This slide is intentionally blank.

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