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  1. Monday, May 6th Genetics is the study of how parents traits (characteristics) are passed down to their offspring. 1. Write down 2 questions you have about Genetics 1 Minute 4 Minutes Time’s Up! 1 5 2 30 Seconds 3 Minutes 10 2 Minutes 6 7 8 9 4 3 REMINDER: HOMEWORK DUE FRIDAY

  2. Chapter 10: GeneticsMendel’s Contributions

  3. There are at least 250,000 beetle species with a variety of different characteristics

  4. Over 400 breeds of dog are recognized around the world, each unique for its personality, habits, and form.

  5. Humans also have multiple characteristics that can vary from person to person

  6. Even plants have a wide array of unique qualities

  7. How do we understand why each individual living thing looks and acts the way it does?

  8. #1 Gregor Mendel • The Father of Genetics • First person to complete successful work on the study of heredity. (1800’s) • He was able to predict how characteristics are transferred from one generation to the next.

  9. #2 Heredity: The passing on of characteristics from parents to offspring Genetics: The branch of biology that studies Heredity

  10. #3 Traits: Characteristics that are inherited from generation to generation

  11. #4 In order to understand the basic mechanisms of heredity, Mendel needed to do experiments He used Pea Plants as his test subjects

  12. Why Peas? • Reproduce sexually • When the pollen from the male part of the flower comes in contact with the female part Fertilization occurs. • 2. Both male and female parts are in the same flower • Pea flowers can self- pollinate • Sperm cells in pollen fertilize the egg cell in the same flower.

  13. Why Peas? 3. Because they self pollinate, pea plants give all of their traits to their offspring 4. If he wanted two different plants to create offspring, Mendel could cross- pollinate them.

  14. #5 Mendel’s Experiments • Mendel noticed that certain pea plants produced the exact same form of a trait generation after generation. Self pollinating parent (First Generation) Self pollinating offspring (Second Generation) (Third Generation) Plants that produce the exact same form of a trait generation after generation are called True- Breeding

  15. #6- #7 He was curious to see what would happen when he cross- pollinated two true breeding plants that had two different forms of a single trait • The offspring of true breeding parents that have different forms of a trait are known as hybrids

  16. #8 The two pea plants being cross pollinated are called the P1- generation (Parental)The offspring of the P1- generation are called the F1 generation (First Filial) When looking at the F1 generation, Mendel noticed something strange happening to the hybrid offspring of the two true breeding parents.

  17. #9 • Mendel noticed that one of the traits was not showing up in the offspring. • It was as if one of the traits never existed at all!

  18. Mendel was curious as to why this happened so he allowed the F1 generation to self pollinate. P1 Cross Pollinate F1 Self Pollinate F2 ? ? ? ?

  19. #10 P1 Cross Pollinate Self Pollinate ¾ Purple ¼ White F1 • Each F1 plant that self pollinated produced offspring that had both purple and white flowers. • The trait that disappeared in the F1 generation reappeared as if from nowhere. F2

  20. Mendel’s Conclusions

  21. #11-#12 • Each organism has two factors that control each of its traits • These factors are genes and are located on chromosomes

  22. #13- #14 • Genes exist in different forms known as alleles • For example, in each pea plant, there are two alleles that determine what color the flower will be. An organisms two alleles are located on different copies of a chromosome- one from mom and one from dad

  23. Conclusion #2 #15- #17 2. There are some alleles that are dominant and some that are recessive • Mendel realized this when all of the F1 generation showed only one of the two possible traits. • He called the observed trait Dominant • He called the trait that disappeared Recessive

  24. #18- #19 Mendel concluded that the allele for purple flowers was dominant to the allele for white flowers. • An organism with a dominant allele for a trait will always express the dominant characteristic. • An organism with a recessive allele for a trait will exhibit the recessive characteristic only when the dominant allele for that trait is not present. x x

  25. #20- #23 • Dominant alleles are represented by a capital letter • Recessive alleles are represented by the corresponding lower case letter F= Purple Color x Purple FF Purple FF White ff White ff x f= White Color Purple FF Purple FF Purple FF Purple FF White ff White ff White ff White ff

  26. Conclusion #3 #24 3. Every individual has two alleles for each gene. x Pure- breeding P generation Purple FF White ff Hybrid F1 generation Purple Ff Purple Ff Purple Ff Purple Ff

  27. Possible Allele Combinations • 1. Two Dominant Alleles (FF) • 2. Two Recessive Alleles (ff) • 3. One Dominant allele and one Recessive allele (Ff)

  28. Tuesday, May 7th • What is the difference between a dominant and recessive trait? • Where do organisms get their 2 alleles from? • 3. If an organism had the alleles Aa, would it show the dominant or recessive trait? WHY? • 4.What are the three potential allele combinations that an organism can have? (Use any letter you want) 1 Minute 4 Minutes Time’s Up! 5 2 1 30 Seconds 3 Minutes 10 2 Minutes 9 8 7 6 4 3 REMINDER: HOMEWORK DUE FRIDAY

  29. 1. What is the difference between a dominant and recessive trait? • If an allele for a dominant trait is present, the dominant trait will be seen in the organism. • If an organism has 2 recessive alleles then the organism will show the recessive trait; however, if the organism has one dominant allele, the recessive trait will be hidden and the dominant trait will be seen. x x

  30. 2. Where do organisms get their 2 alleles from? An organisms two alleles are located on different copies of a chromosome- one from mom and one from dad

  31. 3. If an organism had the alleles Aa, would it show the dominant or recessive trait? WHY? x Pure- breeding P generation Purple FF White ff Hybrid F1 generation Purple Ff Purple Ff Purple Ff Purple Ff

  32. 4. What are the three potential allele combinations that an organism can have? • 1. Two Dominant Alleles (FF) • 2. Two Recessive Alleles (ff) • 3. One Dominant allele and one Recessive allele (Ff)

  33. #25 When the F1 generation self pollinates, both the male and female gametes have to contribute one allele to the offspring. • When fertilization occurs, the male and female gametes randomly pair up. P1 Cross Pollinate Self Pollinate Purple FF White ff F2 generation offspring ¾ Purple ¼ White F f x Ff F1 Purple Ff Purple Ff FF ff F2 Ff Ff

  34. Friday, May 10th • What does pure breeding mean? • Write an allele combination for a pure breeding organism using the letter L • The offspring of two pure breeding organisms is called a . • Write an allele combination for #3 using the letter L ] TURN IN YOUR HOMEWORK!! 1 Minute 4 Minutes Time’s Up! 5 2 1 30 Seconds 3 Minutes 10 2 Minutes 9 8 7 6 4 3

  35. Probability and Genetics • 2. Mendel’s Contributions to Genetics • 3. Trait Lab Things to turn in….

  36. Probability and Punnett Squares

  37. Probability • How likely it is that an event will occur • You can calculate probability by dividing the number of desired outcomes by the total number of possible outcomes • The odds of getting heads is a one in two chance 1: 2 or ½ • The odds of getting tails is a one in two chance 1:2 or ½

  38. 1:6 or 1/6 On a 6 sided dice, what is the probability of getting a 2? On a 6 sided dice, what is the probability of getting a 1 or 4? 2:6 or 2/6

  39. Probability and Genetics • Probability can be used to help us understand what type of traits an offspring could have. • We use something know as punnett squares to find the potential alleles that an offspring can obtain from its parents.

  40. F F x f Ff Ff Pure- breeding P generation f Ff Ff Purple FF White ff Hybrid F1 generation Purple Ff Purple Ff Purple Ff Purple Ff

  41. How to Make a Punnett Square x x Pure- breeding P generation Pure- breeding P generation Male F F Purple FF White ff Purple FF White ff F f F f f Hybrid F1 generation Female f F F f f Purple Ff Purple Ff Purple Ff Purple Ff

  42. What Does A Punnett Square Show Us? F F f Ff Ff f Ff Ff • 1. All of the potential allele combinations that an offspring can have for a trait. • 2. It is NOT showing us 4 different offspring. • 3. It is only showing the probability of what alleles 1 offspring could potentially have based off of the mom and dads allele combinations.

  43. What is the probability of an offspring having the allele combination AA? A A A A A A A A A A A A T t What is the probability of an offspring having the allele combination Tt? T T T T t t T t t t

  44. T t Tall Phenotype: Physical appearance of an organism Genotype: Combination of genes in an organism. t t T t T T Homozygous Dominant Homozygous Recessive Heterozygous Homozygous: When there are two identical alleles for a trait. Dominant: Observed trait of an organism that masks the recessive form of a trait. Recessive: Observed trait of an organism only when the dominant allele is not present. Heterozygous: When there are two different alleles for a trait.