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Sci 9A Lesson 1 Mar 14 - Introduction to Genetics


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Introduction to Genetics

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Sci 9A Lesson 1 Mar 14 - Introduction to Genetics

  1. 1. WARM-UP ACTIVITY <ul><li>1 ) Choose a partner. </li></ul><ul><li>2) On the piece of paper provided, write down one of each of the following letters : </li></ul><ul><li>B or b </li></ul><ul><li>C or c </li></ul><ul><li>W or w </li></ul><ul><li>D or d </li></ul><ul><li>L or l </li></ul><ul><li>F or f </li></ul><ul><li>P or p </li></ul><ul><li>3) Hang on to your paper – don’t show any other group! </li></ul>Example: b C W D l f P
  3. 3. NOTE: <ul><li>Terms in green are definitions </li></ul><ul><li>– these are key terms to know </li></ul><ul><li>Terms in blue are important words or concepts </li></ul><ul><li> – please make note </li></ul>
  4. 4. <ul><li>Who was Gregor Mendel? </li></ul><ul><li>1822-1884 </li></ul><ul><li>Austrian monk </li></ul><ul><li>Known as the </li></ul><ul><li>“ Father of Genetics” </li></ul>
  5. 5. <ul><li>Gregor Mendel </li></ul><ul><li>Studied the inheritance of traits (characteristics) in pea plants </li></ul><ul><ul><li>Found that the plants’ offspring retained traits of the parents </li></ul></ul><ul><li>From these experiments, Mendel developed The Laws of Inheritance </li></ul>
  6. 6. Definitions: trait: a characteristic that can be passed from parent to offspring heredity: the passing of traits from parents to offspring genetics: the study of heredity
  7. 7. <ul><li>Inheritance </li></ul><ul><li>Mendel stated that physical traits are inherited as “particles” </li></ul><ul><li>Mendel did not know that the “particles” were actually chromosomes and DNA </li></ul>
  8. 8. Traits in Pea Plants Pea plants have many different traits Some traits are dominant over others Allele: a form of a gene (different bases along the DNA) Dominant: allele that is expressed (regardless of its counterpart allele); represented by a capital letter (e.g. T) Recessive: allele that is expressed only when its counterpart allele is also recessive ; represented by a small letter (e.g. t) Examples of traits in pea plants
  9. 9. PUNNETT SQUARE <ul><li>Used to help solve genetics problems </li></ul><ul><li>Shows what the offspring of a female and male parent will look like </li></ul>An example of a Punnett square Male Female
  10. 10. PUNNETT SQUARE <ul><li>What alleles will the offspring of two parents have? </li></ul><ul><li>What will the offspring look like? </li></ul>Genotype: the combination of alleles for a trait e.g. TT, Tt, tt Phenotype: the physical feature resulting from a genotype e.g. tall, short Short
  11. 11. GENOTYPE AND PHENOTYPE Genotype of alleles: P = purple flower p = white flower All genes occur in pairs, so 2 alleles affect a characteristic Possible combinations are: Genotypes PP Pp pp Phenotypes purple purple white
  12. 12. GENOTYPES <ul><li>Homozygous genotype: </li></ul><ul><li>gene combination involving 2 dominant or 2 recessive genes (e.g. TT or tt) ; also called pure   </li></ul><ul><li>Heterozygous genotype: </li></ul><ul><li>gene combination of 1 dominant and 1 recessive allele (e.g. Tt) ; also called hybrid </li></ul><ul><li>Note: Heterozygous offspring will express the dominant allele (T) over the recessive allele (t) because the dominant allele is ‘stronger’ than the recessive allele </li></ul>
  13. 13. GENERATION “GAP” <ul><li>Parental P 1 generation: the parental generation in a breeding experiment. </li></ul><ul><li>F 1 generation: the 1 st generation offspring in a breeding experiment (1st filial generation) </li></ul><ul><ul><li>Result from breeding individuals from the P 1 generation </li></ul></ul><ul><li>F 2 generation: the 2 nd generation offspring in a breeding experiment (2nd filial generation) </li></ul><ul><ul><li>Result from breeding individuals from the F 1 generation </li></ul></ul>
  14. 14. GENERATION “GAP” Parent generation (P1) 1 st filial generation (F1) 2 nd filial generation (F2)
  15. 15. BREED THE P1 GENERATION P1 = tall (TT) x short (tt) pea plants T T t t
  16. 16. BREED THE P1 GENERATION: SOLUTION P1 = tall (TT) x short (tt) pea plants t t T T Tt Tt Tt Tt All Tt = tall (heterozygous tall) produces the F 1 generation
  17. 17. BREED THE F1 GENERATION F1 = tall (Tt) x tall (Tt) pea plants T t T t
  18. 18. BREED THE F1 GENERATION: SOLUTION F1 = tall (Tt) x tall (Tt) pea plants T t T t TT Tt Tt tt produces the F 2 generation 1/4 (25%) = TT 1/2 (50%) = Tt 1/4 (25%) = tt 1:2:1 genotype 3:1 phenotype
  19. 19. FOLLOWING THE GENERATIONS Cross 2 pure plants TT x tt Results in all hybrids Tt Cross 2 hybrids, results in 3 Tall & 1 Short TT, Tt, tt
  20. 20. GREGOR MENDEL RAP <ul><li> </li></ul>
  21. 21. ACTIVITY! <ul><li>As budding scientists, you will get the chance to see the results of a cross of the P1 parental generation! </li></ul><ul><li>How, you may ask? </li></ul><ul><li>Well, by making your own sperm and eggs! </li></ul>
  22. 22. INSTRUCTIONS <ul><li>1) Working with a partner, you will be assigned the </li></ul><ul><li>task of making either a paper maché sperm or an egg. </li></ul><ul><li>2) Add your group’s piece of paper with your genetic code inside the balloon provided. </li></ul><ul><li>3) Blow up your balloon, tie it off, and begin paper maché-ing! The supplies will be provided on your lab bench. </li></ul><ul><li>4) Only put 2 layers of newsprint around your balloon or it won’t dry. </li></ul><ul><li>5) Leave your balloon to dry on top of a big piece of newspaper. </li></ul><ul><li>6) Add your group members’ name to the tie of the balloon using a piece of masking tape. </li></ul>
  23. 23. HOMEWORK FOR NEXT CLASS: <ul><li>Complete the Genetics Practice Problems worksheet </li></ul><ul><li>Read over class notes and check out the class blog: </li></ul>
  24. 24. WORKS CITED <ul><li>Images taken from the following sources: </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li>PowerPoint source: </li></ul><ul><li>Copyright C. Messengale </li></ul>