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2 makes all offspring exactly like itself. Genotype = D D, or dd, not D d What is a true bleeding plant THINK PAIR SHARE 2

3 Mate organisms with each other. cross THINK PAIR SHARE 3

4 11. physical characterisistic such as seed color, hair color. Trait THINK PAIR SHARE 4

5 segment of DNA that codes for a particular trait Gene THINK PAIR SHARE 5

6 variations of the same trait, such as blue or brown eyes. Allele THINK PAIR SHARE 6

7 Overpowers recessive trait. Dominant THINK PAIR SHARE 7

8 overpowered by dominant trait Recessive THINK PAIR SHARE 8

9 When an allele shows up physically in offspring. Expressed THINK PAIR SHARE 9

10 the likelihood that a particular event will happen. Probability THINK PAIR SHARE 10

11 not affected by previous events, can happen by chance. THINK PAIR SHARE Random Event 11

12 separation. In this section of biology, refers to genes and alleles. THINK PAIR SHARE Segregation 12

13 diagram that shows parental genotypes, predicts genotypes of offspring, using simple rules of probability THINK PAIR SHARE Punnet Square 13

14 A plant is homozygous recessive for height. Give its genotype and phenotype. tt. It is short. THINK PAIR SHARE 14

15 A plant is heterozygous for height. Give its genotype and phenotype. Tt. It is tall, because T is dominant, and T is tall. THINK PAIR SHARE 15

16 A pea plant has a short phenotype for height. Give its possible genotypes and describe each genotype as homozygous recessive, homozygous dominant or heterozygous. tt. Homozygous recessive. THINK PAIR SHARE 16

17 A pea plant has a tall phenotype for height. Give its possible genotypes and describe each genotype as homozygous recessive, homozygous dominant or heterozygous. TT homozygous dominant, Tt heterozygous. tt is not possible- the plant is tall. THINK PAIR SHARE 17

18 You cannot predict that. They will have 3 chances in 4 of being brown eyed, but also a 1 in 4 chance of being blue eyed. THINK PAIR SHARE You are heterozygous for brown eyes, and marry a woman heterozygous for brown eyes. You have 4 children together. The first child has blue eyes. 1.What color will the eyes of the other children be? 18

19 1.Its unlikely- each child has only a 1 in 4 chance of having blue eyes. 2.They are not related. Each fertilization is a random event, with the same probability as every other mating. THINK PAIR SHARE You are heterozygous for brown eyes, and marry a woman heterozygous for brown eyes. You have 4 children together. The first child has blue eyes. 1.Is it likely your other 3 children will be blue eyed? Explain. 2.Are the eye colors of your next 3 children related to your first blue eyed child? 19

20 1. The ratio is 3.15:1. 2. The result makes sense. If you had a larger sample size (more seeds, more plants) your result would be closer to exactly 3:1. Punnet squares predict a 3:1 ratio, for MANY crosses, not just 1. THINK PAIR SHARE You get the following numbers of seeds, with the phenotypes shown, for a self cross of a plant heterozygous for round and wrinkled seeds… 705 round:224 wrinkled. 1.Calculate the lowest ratio, to 3 decimal places. 2.Is this a logical result, or is something wrong? Explain your answer. 20

21 1. How many alleles can you have for a single gene? 2. How many alleles can a species have for a single gene. 1.Two maximum. 2.You can have 4 or even more alleles for a single gene in a species. THINK PAIR SHARE 21

22 1.What is the root cause of independent assortment of alleles? THINK PAIR SHARE 1.Meiosis. 22

23 1.Compare incomplete dominance to codominance, and also give an example of each. THINK PAIR SHARE Incomplete dominance results in both alleles partly expressed so that the result looks like a MIX of both alleles. In other words, both are expressed, but not completely. Example- white and red flowers of Mirabilis sp. When crossed give a mix, pink, of the alleles. In codominance, both alleles are expressed equally. Erminette chickens- cross BB with WW and get BW offspring, which have black and white feathers, not grey feathers. 23

24 1.What is the effect of multiple alleles on a population? 2.Can an individual have multiple alleles? THINK PAIR SHARE 1.More variability. 2.No- an individual has 2 alleles at most, one from each parent. 24

25 1.A specific trait in a population is affected by more than one gene. What do we call this condition? THINK PAIR SHARE 1.Polygenic inheritance. 25

26 1.Which genes below are most likely to crossover together during meiosis? A and C or A and D. 2.Explain your answer in terms of physical location of the genes. THINK PAIR SHARE 1.A and C. 2.Because they are closer together. The closer you are to another gene, the more likely you are to cross over. 26

27 1.Explain the relationship between crossover and a gene map. THINK PAIR SHARE 1.A gene map is really a math model of how likely genes are to crossover together. 27

28 Sort the topics below into “Mendel” and “Post Mendel”. In other words, which topics are come from Mendel, and which topics did we discover later on? Answer is on next slide. THINK PAIR SHARE Heredity Gene Trait Segregation Allele Independent assortment Codominance Dominant Recessive Incomplete dominance Polygenic inheritance Gene maps Gene linkage 28

29 Sort the topics below into “Mendel” and “Post Mendel”. In other words, which topics are come from Mendel, and which topics did we discover later on? Answer is on next slide. THINK PAIR SHARE Mendel Heredity Trait Segregation Independent assortment Dominant Recessive Post Mendel Incomplete dominance Polygenic inheritance Gene maps Gene linkage Gene Allele Codominance 29

30 Mendel discovered basic ideas about genetics, but did not discover crossover. Explain why you think he didn’t discover this important genetic idea. THINK PAIR SHARE The genes he studied were all far apart or on different chromosomes- they could not have crossed over. If he had chosen traits that WERE linked, he might not have figured out the basic laws that he did discover. 30

31 Were any of the genes Mendel studied codominant or incompletely dominant? Explain your answer. THINK PAIR SHARE No. He got no intermediate results from crossing traits, which would have been incomplete dominance. He also got no plants that had BOTH traits expressed equally. If he had, just as with crossover, he might have never discovered the basic genetic principles. 31

32 Mendel found some plants had both forms of some traits. For example, plants had both round and wrinkled peas. Explain why this was not codominance. THINK PAIR SHARE True- he got round and wrinkled seeds on the same plant, but they were always in 3;1 ratio, meaning they were strictly the result of dominance and recession. 32

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