1 / 63

Dividing & Delivering

How?. Why?. Dividing & Delivering. Distributing genetic information. Lab 7. 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’ ?

evita
Download Presentation

Dividing & Delivering

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. How? Why? Dividing & Delivering Distributing genetic information Lab 7

  2. 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?

  3. ‘Ripped’ from 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 • Headline: Blue eyes result of ancient genetic ‘mutation’ • It’s not a ‘mutation’; it’s a mutation Meaning?

  4. Blinding you with Science (jargon) KNOW THESE • 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! • More in the lab manual & Vocab exercises!

  5. 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 • A human genome is ~3,000,000,000 basepairs • A human genome is (currently guesstimated at) ~20-30,000 genes** • A human genome is ~1 meter of DNA *Includes control regions & stuff that won’t make it into the final product **We keep finding stuff that matters

  6. Genes are on chromosomes (chromosomes are bunched up DNA) • Alleles are different “flavors” of genes • There are two alleles for each gene

  7. Mitosis and Cell DivisionGoals: - Scaling: Nucleotide, Gene, Chromosome--and how many of each Differences between mitosis and meiosis - Predict and describe meiotic results - Master concepts referred to by: allele, dominant, recessive, linkage

  8. It’s all in a name • Chromosome • Gene • Chromatid • Allele • Homologous • Dominant • Recessive • Spindle Fiber • Centromere

  9. 1 “Chromatid” can also be a chromosome; it has all the genes on it.

  10. 1 “Chromatid” can also be a chromosome; it has all the genes on it.

  11. 1 “Chromatid” can also be a chromosome; it has all the genes on it. This

  12. 1 “Chromatid” can also be a chromosome; it has all the genes on it. This Is just a copy of this

  13. So, in this scenario…

  14. From Mother Chromosome 1 Chrm 2

  15. From Father From Mother Chromosome 1 Chromosome 1 Chrm 2 Chrm 2

  16. This is a DIPLOID Nucleus/Cell

  17. Chromosome 1 (from mother) Chromosome 1 (from father)

  18. Chromosome 1 (from mother) Chromosome 1 (from father) Copied during Interphase Copied during Interphase

  19. Chromosome 1 (from mother) Chromosome 1 (from father) Copied during Interphase Copied during Interphase

  20. So after replication…

  21. So after replication… Chromosome 1 (from mother) Chromosome 1 (from father) Chrm 2 Chrm 2 Condensed versions during mitosis/meiosis

  22. This is a DIPLOID Nucleus/Cell

  23. This is ALSO a diploid nucleus/cell

  24. Mitosis and Cell Division Why are chromosomes usually shown like this?

  25. Touching mitosis & meiosis

  26. Your brain: A lousy place to think • 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 bridges

  27. Mitosis and Cell Division • You run a cake-making company • Order comes in for a cake • What information do you need? • It’s ‘old-fashioned’- no photos

  28. Room 430 Room 420 Pay close attention to the nipples! Room 450 Room 460 Symbolism bead = gene String of beads = chromosome = double-stranded DNA Every group gets two long (maternal & paternal version of chromosome I) and two short (maternal & paternal chromosome II). each bead is a GENE--i.e. thousands of nucleotides. The ‘oddball’ beads highlight separate alleles

  29. Mitosis and Cell Division • What comes after MITOSIS?

  30. Clear your mind • Go outside & take a lap around the floor • Do I look like I’m kidding? • Ok, lets watch a youtube video of people getting hit in the nuts… Its relavent-ish. http://www.youtube.com/watch?v=Inj2Ch-oIX8

  31. http://kmarsh2.umwblogs.org/2008/10/24/cartoon-mitosis/

  32. Genotype, phenotype • Pick two traits • Pick a dominant & recessive outcome arising from different alleles • Always have one heterozygous • You choose who you’re mating with (homozygote or heterozygote)…

  33. Meiosis: the other cell division Point to what cells are producing through meiosis? Don’t be shy….

  34. 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

  35. Doing it (making sex) • It’s a huge waste of time… even when other people are involved • Exhausting (sometimes enough is enough already and you just want to go to sleep)… Science calls this “metabolically expensive,” psychology calls it the “refractatory period,” you may call it “get out, I’m going to sleep”

  36. Jack Sprat and his lipase-deficient disease Jack Sprat could eat no fat. His wife could eat no lean. And so between them both, you see, They licked the platter clean

  37. Why have sex? • Suppose I’m Jack Sprat; you’re my wife. • I have the mutant form of the fat-eating gene; you of the lean-eating gene • If we reproduce asexually (mitotically), how long until some descendant can eat a whole pig? • If sexually, i.e. by taking parts of our holdings & throwing them together in an offspring?

  38. Thinking it through • How much are you ‘like’ your ma & pa? • How much of your genome should you give your child if he/she is not uni-parental?

  39. Meiosis • Let’s do it • How diverse are your ‘gametes’? • Is that enough?

  40. Meiosis • Recombination • ‘Homologous’ chromosomes can exchange genes

  41. 1 3 2 Meiosis Where should the circled site on Chromo1 recombine with Chromo2?

  42. Meiosis • Pick two ‘traits’ • What is dominant/recessive?

  43. Meiosis • First, make a copy--b/c that’s the way it happens • Pair the pairs: duplicated mom’s & dad’s contributions pair • Recombine (randomly)

  44. Meiosis • Now we’ve recombined; how to separate? • When is a cell haploid? • Select a gamete, go fuse with a classmate • Stop by and show me the genotype

  45. Meiosis • Diversity? • Two chromosomes with recombination • How many possibilities?

  46. Meiosis • Crossing Over is GREAT for genetic diversity!!! • What are the ‘costs’?

  47. Things go wrong during Meiosis • Non-disjunction • Insertion • Deletion • Inversion

More Related