Inheritance Presentation (2012-2013)


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My presentation from the Inheritance and Evolution unit, 2012-2013.

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Inheritance Presentation (2012-2013)

  1. 1. Hereditary Genetics Hereditary means something which is passed on from one generation to the next. What are we talking about?
  2. 2. What do we Inherit from our Parents?
  3. 3. What are?● Chromosomes?● DNA?● Genes?● CG, AT?● Why can two right-handed parents have a left- handed child?● Why do some people look different to their parents?● What causes some people to be born disabled?
  4. 4. Chromosomes● Most cells contain a nucleus● The nucleus contains long, thin strands of DNA (deoxyribonucleic acid).● The DNA contains the code to make every part of an organism.● Instructions for a particular characteristic is called a gene.
  5. 5. Chromosomes and DNA
  6. 6. Chromosomes in a Cell
  7. 7. A Real Photo
  8. 8. Human ChromosomesHomologouschromosomes
  9. 9. Chromosome Pairs● Chromosomes always come in pairs. Humans have 23 pairs.● Each chromosome in the pair contains instructions for the same genes. The instructions may be the same or different, eg blonde hair and black hair, or right handed or left handed.● In organisms which undergo sexual reproduction, one chromosome is inherited from each parent. Sex cells (eg sperm, egg, pollen) contain one chromosome from each pair, so 23 chromosomes.
  10. 10. Spotlight Science● Page 7.
  11. 11. Mitosis Mitosis is for growth and http://www.accessexcellence.orepair of tissue.
  12. 12. Meiosis Meiosis produces sex cells, or gametes (sperm and egg)Each gamete has half the number of chromosomes – one from each pair. Each allele is stored on one chromosome. l
  13. 13. MendelMendel was an Austrian Monk who worked with peas. Wheres Austria?
  14. 14. Mendel Used Peas Mendel studied characteristics.A characteristic is something which can change. Mendel studied five characteristics in peas.
  15. 15. Pollination and Flowers
  16. 16. Cross Pollination
  17. 17. First Generation PlantsImage from a Japanese textbook:
  18. 18. Third Generation PlantsThe second generation plants flowers were all pink.When the second-generation flowers were self-pollinated,three quarters of the third-generation had pink flowers andone quarter and white flowers.From this Mendel determined that each of the second-generation pea plants contained one pink gene from one oftheir parent plants, and one white gene from the otherparent. Since they were all pink, he determined that thepink gene would always show up if present; he called thisthe dominant gene.The recessive gene recedes and can remain hidden forseveral generations, and only appears when no dominantgene is present.
  19. 19. VocabularyA characteristic is a feature which can take different forms, eg hair colour, handedness.A trait is a possible form of a characteristic, eg blonde hair, left handed. A gene is the instruction for an inherited characteristic.Different forms of a gene are known as alleles, which are written as letters. A dominant allele will always show up. Its written as a capital letter.A recessive allele will only show up if there is no dominant. Its written as a lowercase letter.
  20. 20. MORE vocabulary HHEveryone has two alleles for each gene, with one from each parent. A genotype is the the genes, written as two letters.A phenotype is the physical characteristic that we can see.
  21. 21. Punnet Squares A punnet square is used to calculate the probability of outcomes. Probability does not mean it will happen.There is a one in two chance of a head when I flipa coin, but this doesnt mean I will always get half heads.
  22. 22. Discontinuous Human Characteristics All these are controlled by one gene in humans. These show more variation in Europeans. Why? Images in my presentation from class included a Europeansailing ship, the Josean Empire (Korean) logo and the Great Wall of China.
  23. 23. Tongue Rolling
  24. 24. Hitchhikers Thumb
  25. 25. Hair ColourDark (brown / black) hair is dominant to light-coloured hair (blonde, ginger etc).Like all these examples, this is a simplification ashair colour is controlled by many different genes.
  26. 26. Eye ColourDark (brown / black) eyes are dominant to light-coloured eyes (blue, hazel etc).
  27. 27. Punnet Squares Example Right handedness (H) is dominant to left handedness (h). A right handed parent who alsocarries the left handed allele has four children with a left handed parent. a) draw a punnet square for this cross. b) what is the probability that each child will be right handed? c) how many of the six children would you expect to be left handed?
  28. 28. More Vocabulary Homozygous means both alleles are the same. 1. Homozygous dominant means both alleles are dominant. 2. Homozygous recessive means both alleles are recessive.3. Heterozygous means both alleles are different. Which one will have a recessive phenotype? Which one will have all children the same?
  29. 29. 1. Ayumi, who is homozygous right handed, has four children withSatoshi, who is left handed.A) Write down the genotypes and phenotypes of Ayumi and Satoshi.B) Draw a punnet square to calculate the genotype and phenotype oftheir offpsring.C) Explain why all of the children are right handed.2. One of Ayumi and Satoshis children, Atsumi, has children with aYuuto, who is heterozygous. Determine the phenotype ratio forAtsumi and Yuutos children.3. Black hair B is dominant to blonde hair, b. Mary, who has blackhair, has five children with Bill, who has blonde hair. All the childrenhave black hair.a) What is Marys genotype most likely to be? Explain why we cantbe certain.b) What is the genotype of Mary and Bills children?c) One of Mary and Bills children has children with a blonde hairedperson. What percentage of their children do you expect to haveblonde hair?
  30. 30. Punnet Squares Worksheets In-class work
  31. 31. Male/Female difference Males have an x and a y chromosome. Females have two x chromosomes.Which sex chromosome (x or y) does sperm have? Which sex chromosome do eggs have? Draw a punnet square of this cross.
  32. 32. King Henry VIII King Henry the VIII had a lot of wives.,_Traitors_Gate.jpg
  33. 33. Colour Blindedness Colour blindedness isrecessive on the x chromosome.Which gender ismore liky to be colourblind?
  34. 34. Explain... Explain why colourblindedness is more likely to occur in males than females.Your explanation should be suited to a fifth grade child. It should explain: 1. dominant and recessive.2. X and Y chromosomes and their role in gender3. Why boys are more likely to be colourblind than girls. 4. It should also give an example of what isrequired for a girl and boy to be born colourblind.
  35. 35. Pedigree Charts
  36. 36. Sex Chromosome Problems Sometimes errors occur during meiosis (the production of gametes) and the zygote (sperm and egg combined) have the wrong number of sex chromosomes.In class we looked at a few of the more common syndromes that result from sex chromosome abnormalities, however I do not expect you to remember what they all are.
  37. 37. Quick Review1. Who was Mendel?2. Mendel found that smooth peas are dominantto wrinkled peas. Mendel crosses two pea plantswhich are both heterozygous for pea texture.Draw a punnet square to show the cross, anddetermine the phenotype ratio of the offspring.3. Tall pea plants are dominant to short peaplants. A pure-breeding (homozygous) short peaplant is crossed with a heterozygous pea plant.Determine the phenotype ratio of the offspring.
  38. 38. Pedigree Charts
  39. 39. Pedigree Charts● A pedigree chart is a diagram which shows the phenotypes for one gene through generations.● A female is represented by a circle and a male a square.● A filled in (black) shape represents the presence of one phenotype and an empty (white) shape represents the other phenotype.● The dominant trait can be determined because two parents with the ____________ trait can have offspring with the __________ trait, but not vice versa.
  40. 40. The Cryptogram The human genome contains over three billionbase pairs, about one and a half percent of which stores codes for twenty three thousand proteins, and the rest stores other information, including controversial "junk DNA" which has no known purpose. The total amount of data is about six hundred megabytes. Each cell copies this entirecode during mitosis, and it only takes about eighty minutes to copy the entire genome. Cells very rarely copy any of the code incorrectly, but if a mistake is made, it is called a mutation, and can be good, bad or have no effect.
  41. 41. PosterDesign an A3 poster to show your familys genotypes and phenotypes. 1.Include as many people as possible. 2. It should be a pedigree chart, but style can vary. (eg it doesnt need to use squares and circles if its obvious) 3. It may include photos or pictures. 4. If possible, show them with the phenotype, egrolling their tongue or holding a pen in one hand. Be creative.
  42. 42. DNADNA = Deoxy--ribo-- nucleic AcidIt stores the code tomake all living things. It is like a recipe book.Its shape is a double helix, like a twisted ladder.Image source: wikipedia
  43. 43. DNA is made of four Nucleotidesdifferent nucleotides joined together. Each one has a sugar, a phosphate and a base. The base is the only part that is different. A always pairs with T. G always pairs with C. Please only learn the above; dont memorise the structure ofthe DNA molecule. This image is included because it is licensed under Creative Commons.
  44. 44. How the Code is StoredThe order of the base pairs stores code forproteins. Every part of our body is made of protein, and the code is in our DNA. Our DNA has some differences but is mostly the same. It is also similar to other primates. It is the ORDER of the base pairs which is the same or different.
  45. 45. ProteinsProteins make up all living things. Hair, toenails, skin etc are all made of proteins. Proteins are made of amino acids. There are twenty different amino acids used by animals. A good diagram here:
  46. 46. Quick Review1)Explain the terms DNA, chromosome, gene, genotype, genome, phenotype, dominant, recessive.2)In pea plants, green pea pods are dominant to yellow pea pods. Karina cross-pollinates a heterozygous plant with a plant with yellow pods. a) What colour are the pods of the heterozygous plant. b) Draw a punnet square for the cross. c) Determine the phenotype ratio of the next generation.3)Explain how our DNA stores code to make an organism. You should consider how it is coded and what the information tells.
  47. 47. Incomplete Dominance● Incomplete Dominance occurs when the phenotype of the heterozygous genotype shows some of each of the homozygous phenotypes.● For example, the Snapdragon flower can be: RR = red rr = white Rr = pink
  48. 48. A good diagram here:
  49. 49. Mutations● The human genome is about three billion base pairs long, and it is usually copied without error.● If an error does occur the genes are changed. This is called a mutation.● Mutations usually have no effect, are sometimes harmful and occasionally beneficial.● Blue eyes in humans are a recent mutation, therefore all blue-eyed people share a common ancestor.
  50. 50. Adaptation An adaptation is a change which helps an organism survive and reproduce in its environment.Images:wikipedia
  51. 51. We discussed how similar skeletons of mammals are,as can be shown at the link below, and what scientistsbelieve this tells about our origins (that we arerelated). We also discussed the existence of thetailbone, and how that suggests that humans once hada tail.
  52. 52. Human Influence on Evolution We have studied how species adapt to theirnatural environment, and those that survive are likely to have more offspring. This is called n________ s__________. Humans change the gene pool of many otherspecies by selecting which ones reproduce. This is called selective breeding.Selective breeding is different from g________ e_______ in that organisms can only begenetically combined if they are of the same or similar species.
  53. 53. Carrots It is believed that the carrot was first foundgrowing in present-day Afghanistan around 5000years ago, in colours of white, black and purple. It is believed that this cave drawing Egypt from 2000 years ago is of a purple carrot.We looked at historical drawings of carrots, but of course I dont expect you to remember them! Main idea: humans have selectively bred plants and animal species to the point that most looklittle like their ancestors from thousands of years ago before humans began farming them.
  54. 54. Greeks on CarrotsTheophrastus (371-287bc, Greece), the “father ofBotany” reports of carrots being found in Greece and Asia. Archaeobotanists have analyzed plant DNA inGreek-made pills from a 130 BC shipwreck, and found that the pills appear to contain carrot, parsley, radish, alfalfa, chestnut, celery, wild onion, yarrow, oak, and cabbage.
  55. 55. CowsCattle (cows) have been domesticated by humans since the neolithic period. They are unusual in that they rarely exist in the wild anymore.We have selectively bred cows to produce a lot of milk (and meat?).
  56. 56. Whats Not Good about Selective Breeding Selective Breeding of can cause food to be less healthy than old varieties. We get more food faster, but its not necessarily better. Through selective breeding of cows (and often the use of drugs) the average annual production of milk has increased from 3,300kg per year to 8,500 kg per year in a century.
  57. 57. Evidence for Evolution The fossil record Observable changes within recordable human history, or even smaller times.What is something which evolves very fast, and why?ANS: things with shorter lifespans evolve faster.
  58. 58. Carbon 14Most carbon is carbon-12, which means that it has ________ protons and ______ neutrons. Carbon-14 has an extra two ____________.In the atmosphere, the ratio of carbon-14 to carbon-12 is about 1 : 7 * 1011.Carbon 14 has a half life of 5730 years. This means that every 5730 years, exactly half of the carbon 14 will change into carbon-12. By measuring the amount of carbon-14 in something we can estimate how long since it died.
  59. 59. Simulation dating-game.
  60. 60. Geologic Time Scale At this level I only expect you to remember the order (using PreCambrian, Paleozoic, Mesozoic and Cenozoic) and which types of organisms appeared in each.
  61. 61. Mass ExtinctionsMany species become extinct if they can not adapt to changes in their environment fast enough. At some times during history, many species become extinct.Scientists believe this is due to changes in climate, which may be caused by meteorites.
  62. 62. PangeaIt is believed that allthe continents wereonce together in one landmass. Pangea means “all Earth”.As the continents drift apart, their climatechanges, so species must adapt.
  63. 63. Why Did they Die?Dinousaurs died out about 65.5 million years ago. Why?Heat generated caused fires, and the smoke and dust blocked out the sunlight, so theplants all died out, leaving the dinosaurs with nothing to eat.
  64. 64. Hominids The human-like family of primates are called hominids. All hominids walk upright. Even though our skeletons are similar toChimpanzees, hominids are unique in that their skeletons are built for walking upright.
  65. 65. Lucy Lucy is a skeleton ofAustralopithicus Afarensis, found in Ethiopia (where?) in 1974. Several hundred bones werefound, and they are estimated tomake up about 40% of her whole skeleton.She walked like a human, but was only 1.1m tall.She is estimated to have lived 3.2 million years ago.
  66. 66. Neanderthal Neanderthals lived in Europe and Asia from about 230 000 until as recently as 30 000 years ago.Please dont learn these figures!They had clothing, tools, art and culture. No one knows whatcaused them to die out.,_modelo_en_Neand-muzeo.JPG
  67. 67. Homo Sapiens We are Homo Sapiens. We left Africa between 40 000 and 100 000 years ago. Early homo sapiens had an organised andcomplicated society, with a lot of art, sculpture, paintings etc.
  68. 68. The EndNext Unit: Chemicals and Their Reactivity
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