Title: Lecture 17 Gametogenesis at the Chromosomal level: Mitosis and Meiosis
1 Lecture 17Gametogenesis at the Chromosomal level Mitosis and Meiosis
Animal Science 434
John J. Parrish
2 Definitions Chromosome - linear DNA molecule Centromere - special region of spindle attachment 3 Definitions A chromatid pair has an identical sequence of DNA 4 Cell Cycle M Go MPF MPF MPF G1 G2 MPF MPF MPF MPF Interphase S 5 M - Phase
6 Grand Scheme Mitosis Meiosis 2N 2N Replicate Division Replicate Division 2N 2N 2N 2N Division N N N N 7 Mitosis Go G1 M - phase Prophase S G2 Metaphase Homologous chromosomes pair along side of each other Chromatids Centromere MPF high Spindles (microtubules) 8 Mitosis Anaphase MPF decreases Chromatids pull apart 9 Mitosis Anaphase MPF decreases Chromatids pull apart 10 Mitosis Telophase Chromosomes pull apart further Microtubules Disappears Nuclear envelopes reform 11 Mitosis Telophase Chromosomes pull apart further Microtubules Disappears Nuclear envelopes reform 12 Mitosis Cytokinesis 13 Mitosis Cytokinesis 14 Meiosis 2N 4N Go G1 G2 S Prophase Primary Spermatocyte Primary Oocyte 15 The Five Phases of Meiotic Prophase
Homologous chromosomesbegin to pair
4N 16 The Five Phases of Meiotic Prophase
Pairing is completed
Crossing over of homologues occur
Oocytes stop here before puberty
Homologous chromosomes pull apart but remain attached at crossover points (chiasma)
RNA synthesis is possible
4N 17 The Five Phases of Meiotic Prophase
RNA synthesis stops
The chromatids become visible
4N Homologous chromosomes linked at chiasma Chromatids linked at centromere Crossover (chiasma) Centromere 18 Metaphase I of Meiosis 4N Homologous chromosomes move toward opposite poles and pair across from one another Homologous chromosomes held together via chiasma 19 Anaphase I of Meiosis 4N Recombination as a result of crossing over 20 Telophase I 4N 21 Telophase I Cytokinesis 4N Secondary Spermatocyte orSecondary Oocyte 22 Meiosis Metaphase II 2N 2N No Replication Rest Same As Mitosis 2N 2N Oocytes stop here until fertilized 23 Meiosis This does notexist for oocyte Telophase II Cytokinesis Anaphase II N N 2N Spermatid N 2N N 24 Abnormalities
PowerShow.com is a leading presentation/slideshow sharing website. Whether your application is business, how-to, education, medicine, school, church, sales, marketing, online training or just for fun, PowerShow.com is a great resource. And, best of all, most of its cool features are free and easy to use.
You can use PowerShow.com to find and download example online PowerPoint ppt presentations on just about any topic you can imagine so you can learn how to improve your own slides and presentations for free. Or use it to find and download high-quality how-to PowerPoint ppt presentations with illustrated or animated slides that will teach you how to do something new, also for free. Or use it to upload your own PowerPoint slides so you can share them with your teachers, class, students, bosses, employees, customers, potential investors or the world. Or use it to create really cool photo slideshows - with 2D and 3D transitions, animation, and your choice of music - that you can share with your Facebook friends or Google+ circles. That's all free as well!
For a small fee you can get the industry's best online privacy or publicly promote your presentations and slide shows with top rankings. But aside from that it's free. We'll even convert your presentations and slide shows into the universal Flash format with all their original multimedia glory, including animation, 2D and 3D transition effects, embedded music or other audio, or even video embedded in slides. All for free. Most of the presentations and slideshows on PowerShow.com are free to view, many are even free to download. (You can choose whether to allow people to download your original PowerPoint presentations and photo slideshows for a fee or free or not at all.) Check out PowerShow.com today - for FREE. There is truly something for everyone!