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Genetic Fundamentals & Gregor Mendel

Genetic Fundamentals & Gregor Mendel. Dr. Rick Woodward Chapters 9 & 10 (New/Green Text Book). January 12, 2011 Wednesday. Today’s Agenda: -Journal Questions: Why do you think the study of genetics is important? What is your New Year’s resolution/goal?

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Genetic Fundamentals & Gregor Mendel

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  1. Genetic Fundamentals & Gregor Mendel Dr. Rick Woodward Chapters 9 & 10 (New/Green Text Book)

  2. January 12, 2011Wednesday Today’s Agenda: -Journal Questions: Why do you think the study of genetics is important? What is your New Year’s resolution/goal? -Turn in your gene mutation winter break project. *1. Lecture: Genetics & Mendel’s Laws –Slide 36 2. Genetic Traits Activity: How alike are we? 3. Work on page 43 in packet: Heredity 4. Video: “Ghost in your genes” 5. Homework: Read Chapter 9 “Mendel Genetics” (page 164 - 183: Second page of packet)

  3. The Genesis of Genetics A. Genetics was founded with the work of Gregor Johann Mendel, an Austrian monk who experimented with garden peas.

  4. Mendel’s Experimental Garden

  5. Situating Mendel Historically (1831-1836) (1859) (1866) (1892) (1910) Darwin on Darwin’s Mendel’s Weismann’s Morgan Mendel born Beagle On the Origin Paper germ plasm finds white Voyage of Speciespublished theory fruit fly • 1815 1830 1845 1860 1875 1890 1905 1920 Napoleon Crimean Formation Mendel’s Sex defeated at War of German work re- chromo- Waterloo (1853-1856) Empire (1870) discovered somes

  6. Genetic Terminology Key Concept! A. Heredity is the transmission of characteristics from parents to offspring. B. A trait is a specific characteristic such as height or eye color.

  7. Genetics Terminology C. Molecular genetics is the study of the structure and function of chromosomes and genes.

  8. Mendel’s Observations A. Mendel observed seven characteristics in pea plants. B. He looked at contrasting traits: 1. Plant height (long or short stems) 2. Seed color (yellow or green) 3. Flower color (purple or white)

  9. Mendel’s Observations C. Mendel studied each characteristic and its contrasting trait individually.

  10. Mendel’s Experiments: Crossed Pea Varieties with 7 Clearly Distinguishable Traits

  11. Mendel’s Observations D. He began by growing plants that were pure for each trait. (1) Plants that are pure for a trait always produce offspring for that specific “pure” trait.

  12. Mendel’s Observations E. The term strain denotes plants that are pure for a specific trait. F. The first strain is referred to as a parental generation, or P1 generation.

  13. Mendel’s Observations G. When the plants matured, he recorded the number of each type of offspring produced by the P1 plant. (1) He called the offspring of the P1 generation the first filial generation, or F1 generation.

  14. F1 x F1 Punnett square F2 genotypes 1/4 SS 1/2 Ss 1/4 ss F2 phenotypes 3/4 smooth 1/4 wrinkled

  15. Terminology A. An allele is an alternative form of a gene. (1) Letters are used to represent alleles. (i.e. T, t) (2) Dominant Trait: TT (Tallness) (3) Recessive Trait: tt (shortness) B. Gene: a segment of DNA that contains coding for a polypeptide or protein; a unit of heredity information.

  16. Terminology C. Punnett Square: Used for predicting the probability that certain traits will be inherited by offspring. (1) Punnett Square = P for Probability

  17. Terminology D. Homozygous: When both alleles of a pair are alike, or the same, the organism is said to be homozygous for that characteristic. AA = RED aa= BLUE

  18. Terminology E. Heterozygous: When the two alleles in the pair are different, the organism is heterozygous for that characteristic. Tt

  19. Terminology F. The genetic makeup of an organism is its genotype (1) Combination of alleles (Rr, rr, RR)

  20. Genotypic Ratio 1. Cross (Tt) (Tt) using a Punnett square. 2. What is the genotypic ratio? Genotypic Ratio = 1TT:2Tt:1tt

  21. Terminology G. Phenotype is the physical appearance or expression of the genotype. (Flower Color) (1) Flower Color is the physical appearance/phenotype.

  22. Phenotypic Ratio 1. What is the phenotypic ratio of a cross between (Tt)(Tt)? • Use a Punnett Square to assist you. 2. The phenotypic ratio is 3 Tall: 1 Short

  23. Ratios F1 x F1 crosses: Mendel also discovered that traits that disappear in the F1 generation reappear in the F2 generation in a 1:3 ratio.

  24. Hybrids A. A hybrid is….. B. A monohybrid cross is a cross between individuals that involves one pair of contrasting traits (TT)(tt) C. A Dihybrid cross is a cross between individuals that involve two pairs of contrasting traits. (BBSS) (ssbb)

  25. Dihybrid cross: F1 generation

  26. Dihybrid cross: F2 generationRatio:9:3:3:1

  27. Hybrid Cross

  28. Dominant versus Recessive Traits

  29. Recessive Traits versus Dominant Traits A. Recessive Trait: Referring to an allele that is masked by the presence of another allele for the same characteristic. (1) Example: T = Tall t = Short tt = Short (recessive trait)

  30. Recessive Traits versus Dominant Traits

  31. Recessive Traits versus Dominant Traits B. Dominant Trait: The dominant trait dominants over a recessive trait unless the recessive trait is homozygous tt = shortness. (1) Example: T = Tall t = Short TT = Tall (Dominant Trait) Tt = Tall (Dominant Trait)

  32. Epigenetics A. May control the expression of our genes. B. Involves the modifications of the activation of certain genes, but not the basic structure of DNA C. Possible Epignetic Processes: 1. Gene silencing 2. Chromosome inactivation

  33. Today’s Activity:HOW ALIKE ARE OUR ALLELES? • Find out the alleles you have for different traits • For each trait, write down whether you express that trait and whether you are dominant or recessive.

  34. 1. TONGUE ROLLING DOMINANT Trait: The ability to roll up the sides of the tongue (RR, Rr) RECESSIVE Trait: Not being able to roll up the sides of the tongue (rr)

  35. 2. 2nd TOE LENGTH • DOMINANT Trait: 2nd toe is longer than the big toe (BB, Bb) • RECESSIVE Trait: 2nd toe is shorter than the big toe (bb) -note the presence of a toe ring.

  36. 3. WIDOW’S PEAK • DOMINANT Trait: Hairline has a point, widow’s peak is present (WW, Ww) • RECESSIVE Trait: Hairline has no point, no widow’s peak (ww)

  37. 4. ATTACHED/FREE EARLOBES • DOMINANT Trait: Earlobes hang freely from the ear (EE, Ee) • RECESSIVE Trait: Earlobes are attached to the side of the face (ee)

  38. 5. HITCHHIKER’S THUMB • DOMINANT Trait: Thumb is straight slightly angled (HH, Hh) • RECESSIVE Trait: Thumb can be bent backwards (hh)

  39. 6. HAIRY KNUCKLES • DOMINANT Trait: No hair on middle parts of fingers (HH, Hh) • RECESSIVE Trait: Hair is present on middle parts of fingers (hh)

  40. 7. DIMPLES • DOMINANT Trait: Dimples present (DD, Dd) • RECESSIVE Trait: No dimples (dd)

  41. 8. CLEFT CHIN • DOMINANT Trait: No cleft present in the chin (CC, Cc) • RECESSIVE Trait: Chin has a cleft or indentation (cc)

  42. 9. STRAIGHT/BENT PINKIES DOMINANT Trait: Pinkies are straight (SS, Ss) RECESSIVE Trait: Pinkies are bent (ss)

  43. HANDEDNESS • DOMINANT Trait: Right-handed (HH, Hh) • RECESSIVE Trait: Left-handed (hh)

  44. Handedness & The Brain

  45. January 13, 2011: Thursday • Today’s Agenda: -Journal Question: What is the difference between a genotype and a phenotype? -What is epigenetics? *(1) Lecture on Mendel’s Laws (finishing unit) –slide 85 (2) Start Face Lab (last pages of your packet.) (3) HW: Finish pages 44, 46, 48 in your packet. (4) Study guide given out next class. -Bring flash cards if you need them. (5) Exam next week on Mendel & Genetics -All work is due on the day of the exam

  46. Mendel’s Laws & Other Key Concepts 1. Mendel’s Law of Segregation 2. Mendel’s Law of Independent Assortment 3. Mendel’s Law of Dominance 4. Mendel’s Law of Incomplete Dominance Other Key Concepts: 1. Blood Types 2. Homologous Chromosomes 3. Crossing Over 4. Sex-Linked Traits (pedigree chart) 5. DNA versus RNA

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