Go to Section: 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?

Go to Section: Important!!! Knowing your vocabulary is especially important in genetics. The better you know the vocabulary in this unit, the easier it will be.

Go to Section: GENETICS Heredity- 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.

Go to Section: 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? Section 11-1 Interest Grabber continued 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

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

Go to Section: 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

Go to Section: 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

Go to Section: 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. Section 11-2 Interest Grabber

Go to Section: 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? Section 11-2 Interest Grabber continued

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

Go to Section: 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)

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

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

Go to Section: Pause for Punnett Square Practice Section 11-3 Interest Grabber

Go to Section: Punnett Square Practice

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

Go to Section: 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

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

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

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

Go to Section: 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

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

Go to Section: Meiosis II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase IIMetaphase IIAnaphase IITelophase II 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. Section 11-4 Figure Meiosis II

Go to Section: Section 11-4 Crossing-Over

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

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

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

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

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

Internet The latest discoveries in genetics Interactive test Articles on genetics For links on Punnett squares, go to and enter the Web Code as follows: cbn For links on Mendelian genetics, go to and enter the Web Code as follows: cbn For links on meiosis, go to and enter the Web Code as follows: cbn Go Online

Section 1 Answers 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.)

Section 2 Answers 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 3 Answers 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.

Section 4 Answers 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? = 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.

Section 5 Answers 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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