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1 Dividing & Delivering Distributing genetic information How?Why?

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Presentation on theme: "1 Dividing & Delivering Distributing genetic information How?Why?"— Presentation transcript:

1 1 Dividing & Delivering Distributing genetic information How?Why?

2 2 Goals for today Scaling: Nucleotide, Gene, Chromosome--and how many of each Concept: Chromosomes are hugely long threads of DNA; some regions are genes PURPOSES of mitosis & meiosis & how these dictate the events Mixing and matching parental DNA made you. It provides hope youre better than them ;)

3 3 The birthday cake gene You are a birthday cake-making company! A call comes in to order a cake. What information must you take? Youre an old fashioned mom-and-pop place; no photos

4 4 Scaling A gene is ~1,000-100,000 basepairs* A chromosome is tens or hundreds of thousands of genes A genome is 1-100s of chromosomes A genotype refers to the alleles present in a given genome Human genome is ~3,000,000,000 basepairs Human genome is (currently guesstimated at) ~20-30,000 genes** Human genome is ~1 meter of DNA *Includes control regions & stuff that wont make it into the final product **We keep finding stuff that matters

5 5 Blinding you with Science (jargon) Gene: A stretch of DNA that represents all the information for a product as well as when and where to make the product Allele: A version (or flavor) of a gene; two alleles of the same gene my differ by a nucleotide or dozens of them--generally a small number Dominant/recessive: Two alleles enter; one allele leaves (which version manifests in the organism) NOT which version is more common! Phenotype – the physical manifestation of a genotype More in the lab manual & Vocab exercises!

6 6 Windows on the gene: eyes Find a brown- and a blue-eyed person. Look deep into their eyes & try to figure out the difference What does it mean genetically when we say brown eyes are dominant? One gene, two alleles Why should that be so? What do brown alleles got that blue do not?

7 7 Ripped from the headlines Blue eyes arise from a DNA change that prevents creation of melanin in the eye specifically Mutation appears identical in all blue-eyed folks, suggesting single origin Headline: Blue eyes result of ancient genetic mutation Headline Its not a mutation; its a mutation [FYI]: On green eyesgreen eyes

8 8 Touching mitosis & meiosis

9 9 Your brain: A lousy place to do your thinking Imagine... You can do a lot of fuzzy math (and fuzzy biology and fuzzy chemistry and fuzzy...) up there Drawing/speaking/writing forces precision; reveals missing links

10 10 Symbolism String of beads = chromosome = double-stranded DNA bead = gene Pay close attention to the nipples!

11 11 Meet the Chromosomes Compare our bead models with image What corresponds?

12 12 Genotype, phenotype Pick two traits Pick a dominant & recessive outcome arising from different alleles You all start off heterozygous

13 13 Mitosis Manually Point at some of your cells that do mitosis? Whats the goal/purpose of this thing called mitosis? So what must happen before mitosis can begin? Do it.

14 14 Mitosis Manually Now what must be achieved? Any half? If not, how pick the appropriate half? How do your final results compare with starting?

15 Mitosis Overview 15

16 16 Clear your mind Go outside & take a lap around the floor Yeah. Go

17 17 Meiosis: the other cell division

18 18 Throwing the dice Sexual reproduction has been compared to a game of roulette in which the players throw away half their chips at every spin of the wheel. Jonathan Silverton, An Orchard Invisible p. 22

19 Meiosis Why have sex?

20 Meiosis Suppose Im Jack Sprat; youre my wife. I have the lean-eating allele of the meat digesting gene; you have the fat-eating allele of the meat digesting gene If we each reproduce asexually (mitotically), how long until one of our descendant can eat a whole pig? If sexually, i.e. by taking parts of our holdings & throwing them together in an offspring?

21 Meiosis How much are you like your mom and dad? How much are you like your siblings? What do you want the cells to look like at the end of meiosis?

22 Meiosis Lets do it How diverse are your gametes?

23 Meiosis Go find another gamete Merge with that gamete Tell me what the genotype of the offspring is How diverse are the offspring?

24 Meiosis Are the resulting offspring diverse enough? Remember: how much are you like your mom, dad and siblings?

25 Meiosis Round 2 Recombination Homologous chromosomes can exchange genes

26 Recombination 26 ef2QWz_ICwDQ&sqi=2&ved=0CAcQ_AUoAQ&biw=831&bih=463#facrc=_&imgdii=BLeNsXzFW6KvYM%3A%3B37itMmpl8jXr2 M%3BBLeNsXzFW6KvYM%3A&imgrc=BLeNsXzFW6KvYM%253A%3BvnFR9MSdzVnnQM%3Bhttp%253A%252F%252Fwww.acce org%252FAB%252FGG%252Fcomeiosis.php%3B450%3B459

27 Meiosis Where should the circled site on Chromo1 recombine with Chromo2? 1 2 3

28 Meiosis Round 2 Do meiosis again, but this time make sure recombination happens. Now weve recombined; how to separate? When is a cell haploid? Select a gamete, go fuse with a classmate Stop by and show me the genotype

29 Meiosis What does recombination do for genetic diversity? What two aspects of meiosis lead to increased genetic variation? Recombination results in even more diversity in the gametes produced via meiosis and the offspring that result from these gametes

30 Meiosis Summary What are the two major results of meiosis? 30

31 31

32 32 Seeing & Believing Mitosis: Turning an onion into a squash Meiosis: Prepared grasshopper testes

33 33 Genes on chromosomes

34 34 Blinding you with Science (jargon) II Linked/Linkage: Referring to whether genes are tethered to one another by virtue of being close on a chromosome Linked: referring to the resulting behavior of traits encoded by such genes

35 35 Think it over... No recombination: every chromosome is a linkage group recombination: new combinations every cross-over (= every gamete)

36 36 Fire it up Load Gameter Interface walk-through: designing the parentals A & B close together on Chromosome II, A further to the right than B, A/A and b/B

37 37 Sciencize it! Explore Observe Hypothesize

38 Genetic Disease Semester Project An opportunity to tie together all the information you have learned in the course up to this point plus what you will learn over the next few weeks A combination of research and original thinking Will be done in pairs Spans weeks 7 – 12 Worth 15% of your final grade

39 Schedule Week 7 (3/3/14) (Mitosis & Meiosis): Part 1 assigned. Students will begin working on it in class and will finish at home. Week 8 (3/10/14) (Meiosis and Phenotype): Part 1 due. Part 2 (structural analysis) assigned, begin working on it in class Week 9 (Ped & Colorblind) (3/24/14): Part 2 is due. TAs hand back parts 1. Part 3 assigned.

40 Schedule cont. Week 10 (Glycol and Ferm): Class discussion of students work on parts 1-3 (30-45 min while fermentation reaction is running) Students will be able to earn ½ points back for making the changes

41 Schedule continued Week 11 (Light Tools): Part 4 (1 page summary of parts 1-3) assigned. Students turn in corrected parts 1-3. Students will be able to earn ½ points back for making the changes suggested Week 12 (Colors & Photosynthesis): Nothing assigned to students. TAs hand back final grade on parts 1-3, so corrections can be applied to part 4. Week 13 (Planning lab 14): Part 4 due Week 15 (Electron Transport): TAs will hand back final grades on Genetic Disease Project

42 Rubric Control Center -> Calendar -> Mitosis Meiosis (week 7) -> Rubric link Open it up. Look through each question carefully and let me know if you have any questions

43 43 A word on research Tying the papers, the observations & your interests together

44 44

45 45 Homework – see control center

46 46 Gameter Linkage refers to the me-too behavior of 2 genes strung together by a relatively small number of nucleotides Postulate: The closer two nucleotides are the (less/more) likely a recombination event is to take place between them Thus, the closer two GENES are on a chromosome, the (less/more) likely it is that the parental state of the chromosome will be passed on intact to offspring

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