This document provides an overview of genetics and Mendelian inheritance. It discusses how Gregor Mendel pioneered the field of genetics through his experiments with pea plants in which he studied traits like height, seed color, and seed shape. The document explains key genetics concepts like phenotype, genotype, dominance, and segregation. It also demonstrates how to use a Punnett square to predict the genotype and phenotype ratios when crossing two parents for a given trait.

1. Genetics A study of inheritance

2. Objectives Understand Phenotype Genotype Dominance Gene Segregation Use a Punnett square to Solve monohybrid crosses Predict genotype ratio Predict phenotype ratio

3. Gregor Mendel Father of modern genetics

4. Gregor Mendel Father of modern genetics Researched with pea plants

5. Gregor Mendel Father of modern genetics Researched with pea plants Developed ideas of dominance and trait segregation

6. Phenotype Phenotype Physical characteristics

7. Genotype Phenotype Physical characteristics Genotype Genes we inherit from our parents

8. Phenotype Facial structure Notice the similarities:

9. Phenotype Facial structure Eyes Notice the similarities:

10. Phenotype Facial structure Eyes Smile Notice the similarities:

11. Phenotype Facial structure Eyes Smile Ears Notice the similarities:

12. Phenotype Facial structure Eyes Smile Ears Nose Notice the similarities:

13. Phenotype Facial structure Eyes Smile Ears Nose Neck Notice the similarities:

14. Mendelian Genetics Mendel studied a number of characteristics in pea plants including: Height - short or TALL

15. Mendelian Genetics Mendel studied a number of characteristics in pea plants including: Height - short or TALL Seed color - green or YELLOW

16. Mendelian Genetics Mendel studied a number of characteristics in pea plants including: Height - short or TALL Seed color - green or YELLOW Seed shape - wrinkled or ROUND

17. Mendelian Genetics Mendel studied a number of characteristics in pea plants including: Height - short or TALL Seed color - green or YELLOW Seed shape - wrinkled or ROUND Seed coat color - white or GRAY

18. Mendelian Genetics Mendel studied a number of characteristics in pea plants including: Height - short or TALL Seed color - green or YELLOW Seed shape - wrinkled or ROUND Seed coat color - white or GRAY Pod shape - constricted or SMOOTH

19. Mendelian Genetics Mendel studied a number of characteristics in pea plants including: Height - short or TALL Seed color - green or YELLOW Seed shape - wrinkled or ROUND Seed coat color - white or GRAY Pod shape - constricted or SMOOTH Pod color - yellow or GREEN

20. Mendelian Genetics Mendel studied a number of characteristics in pea plants including: Height - short or TALL Seed color - green or YELLOW Seed shape - wrinkled or ROUND Seed coat color - white or GRAY Pod shape - constricted or SMOOTH Pod color - yellow or GREEN Flower position - terminal or AXIAL

21. Mendelian Genetics We will work with the following three: Height - short or TALL Seed color - green or YELLOW Seed shape - wrinkled or ROUND Seed coat color - white or GRAY Pod shape - constricted or SMOOTH Pod color - yellow or GREEN Flower position - terminal or AXIAL

22. Predicting Inheritance To determine the chances of inheriting a given trait, scientists use Punnett squares and symbols to represent the genes. UPPERCASE letters are used to represent dominant genes. lowercase letters are used to represent recessive genes.

23. Predicting Inheritance For example: T = represents the gene for TALL in pea plants t = represents the gene for short in pea plants So: TT & Tt both result in a TALL plant, because T is dominant over t. t is recessive. tt will result in a short plant. Remember there are two genes for every trait! One from each parent.

24. Predicting Inheritance For example: T = represents the gene for TALL in pea plants t = represents the gene for short in pea plants So: TT & Tt both result in a TALL plant, because T is dominant over t. t is recessive. tt will result in a short plant. Remember there are two genes for every trait! Mendels’ Principle of Dominance Some genes (alleles) are dominant and others are recessive. The phenotype (trait) of a dominant gene will be seen when it is paired with a recessive gene.

25. Predicting Inheritance Let’s cross a totally dominant tall plant (TT) with a short plant (tt). Each plant will give only one of its’ two genes to the offspring or F 1 generation. TT x tt T T t t

26. Predicting Inheritance Let’s cross a totally dominant tall plant (TT) with a short plant (tt). Each plant will give only one of its’ two genes to the offspring or F 1 generation. TT x tt T T t t Mendels’ “Law” of Segregation Each gene (allele) separates from the other so that the offspring get only one gene from each parent for a given trait.

27. Punnett Squares The genes from one parent go here. The genes from the other parent go here. Tt Tt Tt Tt

28. Punnett Squares T T t Tt Tt t Tt Tt

29. Punnett Squares T T t T t Tt t T t Tt

30. Punnett Squares T T t T t T t t T t T t

31. Punnett Squares T T t Tt Tt t T t T t

32. Punnett Squares T T t Tt Tt t Tt Tt

33. Punnett Squares F 1 generation T T t Tt Tt t Tt Tt

34. Interpreting the Results The genotype for all the offspring is Tt . The genotype ratio is: Tt - 4/4 The phenotype for all the offspring is tall . The phenotype ratio is: tall - 4/4

35. Punnett Squares Your Turn!! T t T ?? ?? t ?? ??

36. Punnett Squares F 2 generation T t T TT Tt t Tt tt

37. Punnett Squares Next, give the genotype and phenotype ratios of the offspring (F 2 generation). T t T TT Tt t Tt tt

38. Punnett Squares Genotype ratio: TT - 1 T t T TT Tt t Tt tt

39. Punnett Squares Genotype ratio: TT - 1, Tt - 2 T t T TT Tt t Tt tt

40. Punnett Squares Genotype ratio: TT - 1, Tt - 2, tt - 1 T t T TT Tt t Tt tt

41. Punnett Squares Genotype ratio: TT - 1, Tt - 2, tt - 1 Phenotype ratio: Tall - 3 T t T TT Tt t Tt tt

42. Punnett Squares Genotype ratio: TT - 1, Tt - 2, tt - 1 Phenotype ratio: Tall - 3, short - 1 T t T TT Tt t Tt tt

43. Punnett Squares This is a monohybrid cross. We worked with only one trait. The height of the plant. T t T TT Tt t Tt tt

44. Punnett Squares This is a monohybrid cross. We worked with only one trait. The height of the plant. Later we will work with a dihybrid cross, using the height of the plant and either seed color or seed shape. two T t T TT Tt t Tt tt

45. Homework - Punnett Squares Questions 1 & 2 on Rats Practice Problems and question 1 on Foxes and Watermelons Practice Problems . T t T TT Tt t Tt tt