Mendel’s Work

1. Mendel’s Work • Gregor Mendel was a priest in the 19th century who loved to garden. • While tending his garden he wondered why some plants had traits similar to their parents, and some plants had different traits then those of their parents. • TRAIT: Each different form of a characteristic that an organism can pass on to it’s offspring.

2. Mendel’s Work • Mendel decided to study heredity. His research would eventually earn him the nick name “the father of genetics”. • HEREDITY: the passing of physical characteristics from parent to offspring. • GENETICS: the scientific study of heredity.

4. Mendel’s Experiment • Mendel started his experiments with purebred plants. • PUREBRED: an organism that is the offspring of many generations that have the same trait. (purebred short pea plants come from short parents and short grandparents, and short great grandparents) – It can be represented by letters TT or pp (all caps or all lowercase)

6. Mendel’s Experiment • Once Mendel had purebred plants, he cross bred plants with different traits with one another.

7. Mendel’s Experiment • In Mendel’s experiments, he called plants in the first cross the parental generation or P generation. • The offspring of the P genertation he called the F1 generation. • The offspring of the F1 generation he called the F2 generation.

8. Mendel’s Results P = Parent Generation F = Daughter or Son 1st Generation F = Daughter or Son 2nd Generation

9. Mendel’s Results • In all of Mendel’s crosses only one form of the trait appeared in the F1generation, however, in the F2 generation the lost form of the trait always reappeared in about ¼ of the plants.

12. Dominant and Recessive Alleles • GENE: A section of the DNA that codes for a specific trait. (hair color gene) • ALLELES: the different forms of a particular gene. (brown or blonde) • An organisms traits are controlled by the alleles it inherits from it’s parents. Some alleles are dominant while other alleles are recessive.

13. These are alleles; different forms of a gene cc – could be alleles for hair color ee- could be alleles for spots hH- could be alleles for straight hair

14. Dominant and Recessive Alleles

15. Dominant and Recessive Alleles

16. Dominant and Recessive Alleles • A dominant allele is one whose trait always shows up in the organism when the allele is present. Represented by a Capital Letter(T) • A recessive allele is one whose trait is hidden when the dominant allele is present. Represented by a Lower Cased Letter(t)

17. Inheriting Alleles and Symbols for Alleles (Purebred vs. Hybrid) • For every trait you have, your DNA is carrying 2 alleles. One came from your mom and one came from your dad. • If both are the dominant version, you show the dominant trait. Ex. TT (purebred) • If both are the recessive version, you show the recessive trait. Ex. tt (Purebred) • If one is the dominant version and one is the recessive version, you show the dominant trait. Ex. Tt (Hybrid)

18. Inheriting Alleles and Symbols for Alleles (Purebred vs. Hybrid) In hybrid allele combinations; if the dominant allele is present then that trait will appear. Recessive traits only appear if both recessive alleles are present. Purebred - Tall Hybrid - Tall Hybrid - Tall Purebred - Short

19. Phenotypes and Genotypes • An organism’s phenotype is its physical appearance or visible traits. (tall, blonde, round seeds, brown eyes) • An organism’s genotype is its genetic makeup or allele combinations. (Tt, bb, RR, Bb)

20. Genotypes • An organism that has two identical alleles for a trait is said to be homozygous. RR= homozygous dominant rr= homozygous recessive • An organism that has two different alleles for a trait is said to be heterozygous. • Rr = heterozygous

21. Section 3The Cell and Inheritance • According to the chromosome theory of inheritance, genes are carried from their parents to their offspring on chromosomes.

22. The Cell and Inheritance • Remember, humans have 46 chromosomes. • Those chromosomes are in pairs. 23 come from the father’s sperm, and 23 come from the mother’s egg. • When the sperm and egg come together, the resulting offspring has all 46 chromosomes.

23. Chromosomes in the same pair carry the same genes, but not necessarily the same alleles. • For example, pair #1 may have the mother’s hair color gene on one chromosome, and the father’s hair color gene on the other chromosome. xx 23 pairs of chromosomes (single copy of the DNA) 23 pairs of chromosomes (duplicated DNA)

25. Meiosis • How do sperm and eggs end up with only half the number of chromosomes? • Instead of dividing by MITOSIS, the parent cells of sperm and eggs divide by a process called meiosis.

26. Meiosis • During meiosis the chromosomes pairs separate and are distributed to two different cells. The resulting cells have only half as many chromosomes as the other cells in the organism.

28. http://www.youtube.com/watch?v=1yu1Zuy_uEQ http://www.youtube.com/watch?v=zglQ2Ildw4I

29. Meiosis • When the chromosomes pairs separate and go into two different sex cells, so do the alleles carried on each chromosome. • One allele from each pair goes to each sex cell.

30. Please Take out your Foldable • Put these Terms on the Back Side of your foldbable • Probability = chance an event will occur • Independence of Events = chances of one event do not effect the outcome of the next event • Punnett Squares = shows combinations of allele possibilities • Phenotype = physical characteristic • Genotype = allele combination (Tt, Bb, hh, FF) • Homozygous = TT (Dominant;purebred) tt(recessive; purebred) • Heterozygous = Tt (hybrid)

31. Mendel’s Results P = Parent Generation F = Daughter or Son 1st Generation F = Daughter or Son 2nd Generation

32. Dominant and Recessive Alleles

33. Dominant and Recessive Alleles • A dominant allele is one whose trait always shows up in the organism when the allele is present. Represented by a Capital Letter(T) • A recessive allele is one whose trait is hidden when the dominant allele is present. Represented by a Lower Cased Letter(t)

34. Inheriting Alleles and Symbols for Alleles (Purebred vs. Hybrid) • For every trait you have, your DNA is carrying 2 alleles. One came from your mom and one came from your dad. • If both are the dominant version, you show the dominant trait. Ex. TT (purebred) • If both are the recessive version, you show the recessive trait. Ex. tt (Purebred) • If one is the dominant version and one is the recessive version, you show the dominant trait. Ex. Tt (Hybrid)

35. Inheriting Alleles and Symbols for Alleles (Purebred vs. Hybrid) In hybrid allele combinations; if the dominant allele is present then that trait will appear. Recessive traits only appear if both recessive alleles are present. Purebred - Tall Hybrid - Tall Hybrid - Tall Purebred - Short

36. DO NOW • PLEASE FINISH FOLDABLE AT HOME • USE MY ANSWERS • Take out your foldable and glue the vocab onto the back side of the last page

37. Section 2Probability and Heredity • Probability is a number that describes how likely it is that an event will occur.

38. Probability • Probability can be expressed as a fraction, or as a percent. • If you flip a coin, there is a one in two chance it will land on heads…. ½, or 50% • If you roll a dice, there is a one in six chance you will roll a 5… 1/6, or about 17%.

39. Independence of Events • When you toss a coin more than once, the results of one toss do not affect the results of the next toss. • Flipping a heads the first time, does not make you more likely to flip a tails the next time.

40. Probability and Genetics Mendel realized that when he crossed tall plant and a short plant, the probability of the off spring in the F1 generation being tall was 4/4 or 100% The probability of the offspring in the F2 generation being tall was ¾ or 75%

41. Punnett Squares • A punnett square is a chart that shows all possible combinations of alleles that can result from a genetic cross.

42. Punnett Squares Capital letters= Dominant allele Lowercase letters= recessive allele Ex. The allele for round seed is dominant over the allele for wrinkled seeds R=round seeds r = wrinkled seeds

43. T = Tall t = short COMPLETE THESE IN YOUR NOTEBOOK

44. T = Tall t = short

45. Please Take out your Foldable • Put these Terms on the Back Side of your foldbable • Probability = • Independence of Events = • Punnett Squares = • Phenotype = • Genotype = • Homozygous = • Heterozygous =

47. Meiosis accounts for probability S = Round Pea s = Wrinkled pea Ss = Round Ss = Round

48. Words to Know • Homozygous – combination of alleles in which both are the same; both dominant (TT) or both recessive (tt) – also known as purebred • Heterozygous – a combination of alleles in which both are different or hybrid; dominant and recessive (Tt)  - also known as hybrid • Phenotype – the actual physical appearance; tall, short, brown eyes, blue eyes, based on the genotype • Genotype – the combination of alleles (TT, Tt, tt); these combinations • Dominant – Alleles that are dominant are represented by a capital letter (“T”) and will always appear (in the phenotype) if they are present • Recessive – Alleles that recessive are represented by a lower cased letter (“t”) and will be masked if a dominant alleles is present