Unit 6 (CH 13,14,15): Genetics - PowerPoint Presentation

1. Unit 6 (CH 13,14,15): Genetics1

2. CH 13: InheritanceGenetics is the study of heredity - or how traits are passed from parent to offspring [INHERITANCE]Individuals share traits because chromosomes carry the same genes at specific locations on the chromosome2

3. What makes us different?3← Twins

4. First, some history...In the mid 1800’s, scientists believed in blending inheritancethis general model involved the permanent blending of a parents’ characteristics in their offspringUntil this guy →Gregor MendelStudied traits of pea plantsseed shape, seed color, flower color, flowerposition, pod shape, pod color, height 4

5. Gregor MendelProblemWhen Mendel crossed tall pea plants and short pea plants, he didn’t get medium plantsHe wanted to predict the traits of offspring from different parents 5

6. Gregor MendelExperimentpeas have distinct traits, so Mendel crossed one true breeding plant with another P generation = true tall x true short → resultsF1 generation = all tall...6

7. he let the F1 plants self-fertilizeresultsF2 generation = 75% tall, 25% were short → 3:1 ratio This happened with any trait he tested!F1: only one traitF2: 3:1 ratio7

8. ConclusionsTraits are controlled by different versions of the same gene Allele: Different versions of the SAME geneone allele inherited from each parent 8

9. A genotype is the actual set of inherited alleles homozygous [true or pure] → inherit two of SAME alleleheterozygous [hybrid] → inherit two DIFFERENT allelesgenotype determines phenotype, or observable trait9

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11. One allele masks the otherLaw of DominanceAlleles are dominant OR recessivedominant allele = italic capital recessive allele = italic lowercase Dominant alleles mask, or cover, recessive alleles [phenotypes]ONE dominant allele inherited = the trait is seenTWO recessive alleles must be inherited to see that trait11

12. All together12Genotype [genes]Phenotype [traits]TThomozygous dominantTongue RollerTtheterozygousTongue Rollertthomozygous recessivenon-tongue rollerTrait: Tongue Rolling

13. Alleles are separated and randomly distributed to gametes during meiosis Law of Segregation13

14. We use punnett squares to predict genetic crossesshows parent alleles, and the resulting possible offspring allelesMonohybrid crosses show the possibilities for one trait 14

15. **capital letters always go first15BB Bb Alleles of parent 1Alleles of parent 2

16. Attached earlobes [D], free earlobes [d]homozygous dom. x homozygous rec.No freckles [A], freckles [a]freckles x heterozygous16

17. Genotypic ratio:HO dom. : HE : HO rec.GG : Gg : ggPhenotypic ratios: dom. trait : rec. trait17

18. brown eyes [B], blue eyes [b]Bb x BBratios?straight hair [R], curly hair [r]rr x RRratios?18

19. A test cross can be used to determine an unknown parent genotype parent 1 = HO recessiveparent 2 = HE or HO dominant?Offspring have dominant phenotype, parent is HO dominantOffspring have recessive phenotype, parent is HE19

20. In Border Collies, black coat (B) is dominant to red coat (b). A breeder has a black male that has won numerous awards, and would like to use the dog for breeding IF he is purebred (BB). To learn this information, she testcrosses him with a red female (bb). If the black male is BB, what kind of gamete (sperm) can he produce? If the red female is bb, what kind of gamete (eggs) can she produce? If the black male is Bb, what kind(s) of gametes (sperm) can he produce? If any of the puppies are red, what is the father's genotype? 20

21. Alleles of two (or more) genes are inherited independently of each otherLaw of Independent Assortmentnot all people with brown hair will have brown eyesThe Law of Segregation addresses the inheritance of a single trait, when in reality, organisms have hundreds of traits!Mendel wanted to know how they worked together - did the inheritance of one trait influence another?21

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23. A dihybrid punnett square predicts the cross of two traitsWe determine the possible gametes using FOIL 23

24. If a parent is BBAa, what are their possible gametes?________, ________, _________, __________If a parent is Bbaa, what are the possible gametes?________, ________, _________, __________Now use these on the sides of your punnett square!24

25. parent 1 on topBA, Ba, BA, Baparent 2 on sideBa, Ba, ba, baComplete the cross.ONLY PHENOTYPIC RATIOS DD : DR : RD : RR25

26. Mendel followed same protocol as monohybrid crossP generationYYRR x yyrr[pure] F1 generationYyRr x YyRr [100% HE] self-fertilize26

27. 27F2 generation9:3:3:1 phenotypic ratio ALWAYS

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29. Unlinked genes form unique recombinant chromosomes during crossing over and independent assortmentfar apart on the same chromosome, or on different chromosomescreate expected 9:3:3:1 ratio29

30. Linked genes only form two combinationsclose together on the same chromosome and inherited together creates 3:1 ratio instead of independent 9:3:3:130

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32. All together now...32

33. Complex InheritanceSome traits have 3 genotypes AND 3 phenotypesIncomplete Dominance: one allele not fully dominant over otherheterozygous = blend of two phenotypesCodominance: both alleles fully expressedheterozygous = shows both phenotypes 33

34. Multiple Alleles: gene controlled by more than 2 allelesDOES NOT mean more than 2 alleles inherited, just that more than 2 existBlood type [and codominance!]A & B alleles are dominant, O is recessiveIAIB = blood type AB [codominance]IAIA or IAi = blood type AIBIB or IBi = blood type Bgenotype ii = blood type O 34

35. Complex InheritancePleiotropy: one gene affects many characteristicsplay a large role in human disordersMarfan syndrome → one gene, many seemingly unrelated traits35

36. Polygenic Traits & Epistasis: traits controlled by many genes working togetherpolygenic - traits controlled by multiple genesheight, eye color, hair color are polygenicAABBCC - very dark skin, aabbcc - caucasian36

37. epistasis - the expression of one gene depends on the presence of anotherfur color in dogs is an exampleblack fur (B) is dominant, brown is recessive (b), but the dominant allele of a different gene (E) causes color to be deposited in the fur, and the recessive gene (e) reduces itE and B = black furE and bb = brownee = yellow fur regardless of B or b alleles37

38. AAAAANNNNDD, the environment can play a role in gene expressionTwins have identical genes, but the environment can influence the phenotypeNature vs Nurtureyou may have the genes for obesity, but with diet and exercise this may not be an issue38

39. Some environmental factors can cause some genes to turn “on” or “off” → epigeneticschange gene expression without changing the DNA sequencetoxic agents, diet and exercise, sunlight, water, temperature, medication, chemicals, and even traumatic experiences can leave molecular scars on our DNAThese changes can work faster than evolution, and are reversible!39

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41. Autosomal DominanceCaused by inheritance of ONE dominant alleleBB - disorderBb - disorderbb - unaffectedThese traits appear in every generationheterozygous x homozygous recessive will produce offspring with a 50% chance of having the disorder 41

42. Achondroplasia: hereditary dwarfism caused by growth factor mutationHutchinson-Gilford Progeria: accelerated aging caused by mutationHuntington’s Disease: impacts brain cell functionno cure, but medications to cope with symptoms, most people die 15-20 years after onset42

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44. Autosomal RecessiveCaused by the inheritance of TWO recessive allelesBB - normalBb - normal, but a CARRIER [no disorder, but could pass it on]bb - disorderThese often skip a generationeach offspring of two carriers has a 75% chance of being normal44

45. Tay-Sachs: caused by a mutation in an enzyme that breaks down a certain type of lipid [fat]fatty acids build up on the brain, cherry red spot on back of eye, causes deafness, blindness, mental retardation, and usual death by 4Albinism: little to no production of the pigment melanin (determines hair, eye, and skin color)also causes vision problems45

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47. X-Linked RecessiveDisorders inherited on the X sex chromosome [X-linked]the Y chromosome is very small and doesn’t carry many genes, it mostly determines sex of the offspringThese are mostly recessive, as dominant X-linked disorders would be lethal to male embryos (they only have one X)47

48. X-Linked RecessiveMen only have one X so these disorders appear in them more oftenWomen have 2 Xs, so they can be heterozygous [carriers] for an X-linked disorderMen can give a “bad X” to their daughters, but not their sons (give them a Y), only a woman can pass the disorder to her son48

49. Red-Green Colorblindness: confuse red and green colorsDuchenne Muscular Dystrophy: absence of protein dystrophin, muscle and nerve cells are replaced with fat cellsHemophilia: blood does not clot properly, prolonged bleeding http://scienceprimer.com/x-linked-inheritance49

50. Changes in Chromosome #Aneuploidy: difference in number of chromosomesautosomal aneuploidy is lethal in humansAneuploidy is a result of nondisjunction → when homologous chromosomes or sister chromatids fail to separate during meiosis, the resulting nuclei will have too few or too much genetic material This affects the chromosome number at fertilization, resulting in offspring with genetic disorders50

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52. Down Syndrome [Trisomy 21]: 3 copies of chromosome 21mild-moderate health impairment, health issues, flattened facial profile, low muscle tone, 1 in 700 birthsEdwards Syndrome [Trisomy 18]: almost every organ system affectedPatau Syndrome [Trisomy 13]: serious eye, brain, and circulatory defects, cleft palate 52

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54. Turner Syndrome [XO]: girls, often short and obesity is common, misdeveloped ovaries [infertility], insufficient sex hormones [delayed puberty]Triple X Syndrome: mild mental impairment, usually no physical or medical problemsKlinefelter Syndrome [XXY]: boys with an extra X, may have learning disabilities, long arms and legs, small testes, and infertility, produce more estrogen than normal malesXYY Syndrome: taller than normal, mild mental impairment54

55. PedigreesA pedigree is a diagram that traces a particular trait through generations of a familyallows us to predict the inheritance of a certain trait or disorder https://www.youtube.com/watch?v=1SZEXbBcYCchttps://www.youtube.com/watch?v=11s5Biyi9q455

56. CH 15: BiotechnologyBiotechnology is the use of an organism, or a component of an organism or other biological system, to make a product or process for a specific use.This could be as simple as beer brewing [using yeast], or as complex as editing an organism’s genesMost biotechnology is based in DNA Technology, which allows us to analyze and manipulate sequences of DNA 56

57. Breeding: bringing together two living things to produce offspringSelective breeding & inbreeding allow for the production of desired traits and elimination of undesirable traits57

58. DNA Profiling: identifying an individual by analyzing the unique parts of their DNAGel Electrophoresis: electric current is used to separate DNA fragments according to size https://learn.genetics.utah.edu/content/labs/gel/58

59. Which women’s baby actually belongs to Mr. Megabucks?59

60. Match each couple the right baby.60

61. Match each couple the right baby.61

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63. Gene Therapy: Gene is transferred into body cells to correct a genetic defect or treat a diseaseTested as a treatment for heart attack, sickle-cell anemia, cystic fibrosis, hemophilia A, Parkinson’s and Alzheimer’s diseases, several cancers, and inherited diseasesSavior Siblings: children conceived with the initial purpose of acting as donors for a sick sibling.embryos are screened during the in vitro process to ensure matches63

64. Genetic Engineering: deliberately modifying an organism’s genome → GMO [genetically modified organism]a gene could be altered and reinserted into the same speciestransferring a gene from one species to another [transgenic]https://www.youtube.com/watch?v=7TmcXYp8xu4Designer Babies: a GM embryo that has traits; chosen by the parent or scientisthttps://www.youtube.com/watch?v=ddn06l23BYQ64

65. Adult Stem Cells: Found in various tissues in the body and might be used to maintain and repair the same kind of tissue. When these mutate cancer occurs. Less controversial because the adult stem cells can be obtained with the consent of their donorInduced pluripotent stem cells: Man-made stem cells. These are created using any cell from an organism. In humans, a person’s skin cell is removed and exposed to chemicals that turn them back into embryonic stem cells. 65

66. Genetic engineering & gene therapy use recombinant DNA (rDNA) which is a sequence of DNA that comes from multiple sourcesA restriction enzyme cuts the DNA from different sources at a specific nucleotide sequence to create manageable chunksThis cut leaves “sticky ends,” fragments are mixed, matching the sticky ends’ base pairs with each other, DNA ligase seals the fragments66

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68. Using recombinant DNA is also how DNA cloning worksDNA cloning involves making MANY copies of a specific piece of DNA [not Dolly]has uses in biopharmaceuticals - making insulin or human growth hormonegene therapy - allow cells to make normal version of bad protein [cystic fibrosis]gene analysis - build recombinant gene to study how it is supposed to work68

69. CRISPR is a powerful new DNA editing techniqueRNA guides a restriction enzyme to a piece of DNA, the enzyme cuts the DNA at that a certain spotA new piece of DNA is put there to repair the breakMost important part is the RNA and DNA can be designed to precisely target and change and essential part of the genomeHIV could be edited out of a person’s cells to prevent relapse Mutations could be removed to cure genetic disordershttps://www.youtube.com/watch?v=jAhjPd4uNFY&t=281s69

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