Punnett Squares. Dihybrid Cross

Transcription

1 Punnett Squares Dihybrid Cross

2 6F: Students will predict possible outcomes of genetic combinations such as monohybrid crosses, dihybrid crosses, and non-mendelian inheritance TEKS

3 Each parent has TWO traits (4 alleles, 2 for each trait) Example: AaBb So each parent can give either a dominant or recessive allele for the first trait (A or a) and a dominant or recessive allele for the second trait (B or b) Determination of Gametes

4 This leads to 4 possible gametes (2 n ) for each parent Determination of Gametes

5 This leads to 4 possible gametes (2 n ) for each parent AB: dominant for both traits Determination of Gametes

6 This leads to 4 possible gametes (2 n ) for each parent AB: dominant for both traits Ab: dominant for trait #1, recessive for trait #2 Determination of Gametes

7 This leads to 4 possible gametes (2 n ) for each parent AB: dominant for both traits Ab: dominant for trait #1, recessive for trait #2 ab: recessive for trait #1, dominant for trait #2 Determination of Gametes

8 This leads to 4 possible gametes (2 n ) for each parent AB: dominant for both traits Ab: dominant for trait #1, recessive for trait #2 ab: recessive for trait #1, dominant for trait #2 ab: recessive for both traits Determination of Gametes

9 Branching Method Determination of Gametes

10 FOIL Method First Outer Inner Last Determination of Gametes

11 Dihybrid Punnett Square

12 Dihybrid Punnett Square

13 Dihybrid Punnett Square

14 Dihybrid Punnett Square

15 Dihybrid Punnett Square

16 A cross with two heterozygous parents always gives the same phenotypic ratio Determining Probability

17 A cross with two heterozygous parents always gives the same phenotypic ratio Both dominant: 9/16 Determining Probability

18 A cross with two heterozygous parents always gives the same phenotypic ratio Both dominant: 9/16 1 st dom; 2 nd rec: 3/16 Determining Probability

19 A cross with two heterozygous parents always gives the same phenotypic ratio Both dominant: 9/16 1 st dom; 2 nd rec: 3/16 1 st rec; 2 nd dom: 3/16 Determining Probability

20 A cross with two heterozygous parents always gives the same phenotypic ratio Both dominant: 9/16 1 st dom; 2 nd rec: 3/16 1 st rec; 2 nd dom: 3/16 Both recessive: 1/16 Determining Probability

21 A cross with two heterozygous parents always gives the same phenotypic ratio Both dominant: 9/16 1 st dom; 2 nd rec: 3/16 1 st rec; 2 nd dom: 3/16 Both recessive: 1/16 9:3:3:1 Determining Probability

22 Due to independent assortment, there is another way to determine probability The probability of two events occurring together is the product of their individual probabilities (ie: multiply the two probabilities together) Example: the odds of flipping two heads in a row on a coin toss is ½ x ½ = ¼ Another Way

23 If you breed two plants that are both heterozygous for being tall and yielding red flowers, what are the chances of getting an offspring that is tall and white? Tall is dominant to short Red flowers are dominant to white flowers Another Way An Example

24 If you breed two plants that are both heterozygous for being tall and yielding red flowers, what are the chances of getting an offspring that is tall and white? Tall is dominant to short T = tall t = short Red flowers are dominant to white flowers Another Way An Example

25 If you breed two plants that are both heterozygous for being tall and yielding red flowers, what are the chances of getting an offspring that is tall and white? Tall is dominant to short T = tall t = short Red flowers are dominant to white flowers R = red r = white Another Way An Example

26 If you breed two plants that are both heterozygous for being tall and yielding red flowers, what are the chances of getting an offspring that is tall and white? Red flowers are dominant to white flowers Tall is dominant to short Parent 1: Parent 2: Another Way An Example

27 If you breed two plants that are both heterozygous for being tall and yielding red flowers, what are the chances of getting an offspring that is tall and white? Red flowers are dominant to white flowers Tall is dominant to short Parent 1: Tt Parent 2: Another Way An Example

28 If you breed two plants that are both heterozygous for being tall and yielding red flowers, what are the chances of getting an offspring that is tall and white? Red flowers are dominant to white flowers Tall is dominant to short Parent 1: TtRr Parent 2: Another Way An Example

29 If you breed two plants that are both heterozygous for being tall and yielding red flowers, what are the chances of getting an offspring that is tall and white? Red flowers are dominant to white flowers Tall is dominant to short Parent 1: TtRr Parent 2: Tt Another Way An Example

30 If you breed two plants that are both heterozygous for being tall and yielding red flowers, what are the chances of getting an offspring that is tall and white? Red flowers are dominant to white flowers Tall is dominant to short Parent 1: TtRr Parent 2: TtRr Another Way An Example

31 Parent 1: TtRr Parent 2: TtRr Another Way An Example

32 Parent 1: TtRr Parent 2: TtRr Another Way An Example

33 Parent 1: TtRr Parent 2: TtRr Another Way An Example

34 Parent 1: TtRr Parent 2: TtRr Another Way An Example

35 Parent 1: TtRr Parent 2: TtRr Another Way An Example

36 Parent 1: TtRr Parent 2: TtRr Another Way An Example

37 Parent 1: TtRr Parent 2: TtRr Probability of tall: ¾ Another Way An Example

38 Parent 1: TtRr Parent 2: TtRr Probability of tall: ¾ Probability of white: ¼ Another Way An Example

39 Parent 1: TtRr Parent 2: TtRr Probability of tall: ¾ Probability of white: ¼ Probability of tall AND white: ¾ X ¼ = 3/16 = 18.75% Another Way An Example

40 Parent Cross: TtRr X TtRr Probability of tall AND white (T-rr) offspring? Compare

41 Parent Cross: TtRr X TtRr Probability of tall AND white (T-rr) offspring? Compare