1 / 50

Lab 7: Mitosis and Meiosis

Lab 7: Mitosis and Meiosis. Mitosis and Cell Division Goals:. 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.

linnea
Download Presentation

Lab 7: Mitosis and Meiosis

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. Lab 7: Mitosis and Meiosis

  2. 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

  3. I want to build a house • What information do I need?

  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

  5. Mitosis and Cell Division

  6. Mitosis and Cell Division • Gene: Segment of DNA that represents all 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!

  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’? • One gene, two alleles • Why should that be so? What do brown alleles got that blue do not?

  8. ‘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?

  9. A Couple Things to Think About…

  10. https://eapbiofield.wikispaces.com/file/view/12_05CellCycle-L.jpghttps://eapbiofield.wikispaces.com/file/view/12_05CellCycle-L.jpg

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

  12. Chromatids and chromosomes

  13. Chromatids and chromosomes Unreplicated chromosome

  14. Chromatids and chromosomes Unreplicated chromosome Replicated chromosome

  15. Chromatids and chromosomes Unreplicated chromosome Replicated chromosome This Is just a copy of this Chromatids

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

  17. This is a DIPLOID Nucleus/Cell

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

  19. So after replication…

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

  21. This is ALSO a diploid nucleus/cell

  22. This is a DIPLOID Nucleus/Cell

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

  24. Mitosis and Cell Division • Pick two traits • Pick a dominant & recessive outcome arising from different alleles • You all start off heterozygous

  25. Pay attention to the ‘nubbins’

  26. Mitosis and Cell Division • -Take a bead model • -What do our bead models represent?

  27. Mitosis and Cell Division • SHOW ME • 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

  28. Mitosis and Cell Division • Point at some of your cells that ‘do’ mitosis? • What’s the goal/purpose of this thing called ‘mitosis’? • So what must the first step be? Do it.

  29. Mitosis and Cell Division • Point at some of your cells that ‘do’ mitosis? • What’s the goal/purpose of this thing called ‘mitosis’? • So what must the first step be? Do it. • Now what must be achieved? • Any half? If not, how pick the appropriate half? • How do your final results compare with starting?

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

  31. Meiosis • Why have sex? • How much of your genome do you want to give your child? • How much are you ‘like’ your mom and dad? • Do ‘mother’ chromosomes have to stay together?

  32. Meiosis – genetic diversity • Just shuffle the chromosomes: all the genes on every chromosome inherited together • Recombine between homologs: one set of genes on a chromosome inherited independently of another

  33. 1 3 2 Meiosis Where should the circled site on Chromo1 recombine with Chromo2?

  34. Meiosis • Remember our traits? • What is dominant/recessive?

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

  36. Meiosis • Now we’ve recombined; how to separate? • How many resulting cells? Ploidy? • What else do we need to do?

  37. Meiosis • Now we’ve recombined; how to separate? • How many resulting cells? Ploidy? • What else do we need to do? • How many resulting cells? What are these cells called?

  38. Meiosis • Now we’ve recombined; how to separate? • How many resulting cells? Ploidy? • What else do we need to do? • How many resulting cells? What are these cells called? • Select a gamete, go fuse with a classmate

  39. Meiosis • Now we’ve recombined; how to separate? • How many resulting cells? Ploidy? • What else do we need to do? • How many resulting cells? What are these cells called? • Select a gamete, go fuse with a classmate • Stop by and show me the genotype

  40. Clean Up No, we’re NOT done

  41. More Vocab… • We’ve talked about chromosomes, mitosis, and meiosis… • Recombining genes via Crossing Over • How likely do you suppose it is that genes are inherited together?

  42. More Vocab… • Linkage’ - referring to whether genes are inherited together because they are ‘close’ on a chromosome • ‘Linked’ - referring to the resulting behavior of traits encoded by such genes

  43. Gameter • Open Gameter • Move things around, work with the buttons • Notice A and a go together • End up with: ‘A’ and ‘B’ on Chrm II, with A farther right than B • Ab and AB

  44. Gameter • Explore • One meiosis • 200 meioses • Move ‘em around and try again • Observe • Hypothesize • Test • Evaluate • See rubric

  45. Disease Presentation

  46. Where we’re headed • Your proposal is an answerable, interesting question • It will reflect causation • Read my comments, revise proposal • Turn in next week

More Related