{"id":218,"date":"2012-11-05T15:42:41","date_gmt":"2012-11-05T19:42:41","guid":{"rendered":"https:\/\/sites.owu.edu\/wolverton\/?page_id=218"},"modified":"2016-12-01T08:50:41","modified_gmt":"2016-12-01T13:50:41","slug":"meiosis","status":"publish","type":"page","link":"https:\/\/sites.owu.edu\/wolverton\/teaching\/cell-bio\/meiosis\/","title":{"rendered":"Meiosis"},"content":{"rendered":"<p><!--:en--><\/p>\n<h2>Links<\/h2>\n<p><a href=\"http:\/\/www.nature.com\/principles\/ebooks\/introduction-to-cell-biology-4570805\/4570005\">Principles Module 38<\/a><\/p>\n<h2>Objectives<\/h2>\n<ul>\n<li>Explain the similarities and differences between meiosis and mitosis<\/li>\n<li>Describe how meiosis produces greater genetic variation<\/li>\n<\/ul>\n<h2>Key Points<\/h2>\n<h3>Features of meiosis<\/h3>\n<ul>\n<li>synapsis: homologous chr pair\n<ul>\n<li>form synaptonemal complex, binds hom. chrom. together\n<ul>\n<li>composed of variant of cohesin<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<li>crossing over: exchange of bits of DNA btw hom. chrom.\n<ul>\n<li>results in recombination, mixing of genes<\/li>\n<\/ul>\n<\/li>\n<li>2 rounds of division\n<ul>\n<li>first separates hom. chrom.\n<ul>\n<li>reduces chrom number (diploid to haploid)<\/li>\n<\/ul>\n<\/li>\n<li>2nd like mitosis, but no replication before it<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h3>Process<\/h3>\n<p>Starting with a cell that is beginning meiosis and has completed S phase:<\/p>\n<div id=\"attachment_323\" style=\"width: 565px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round0.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-323\" class=\"size-full wp-image-323\" src=\"https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round0.jpg\" alt=\"cell after S phase\" width=\"555\" height=\"536\" srcset=\"https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round0.jpg 555w, https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round0-300x290.jpg 300w\" sizes=\"auto, (max-width: 555px) 100vw, 555px\" \/><\/a><p id=\"caption-attachment-323\" class=\"wp-caption-text\">cell after S phase, before meiosis<\/p><\/div>\n<p>After meiosis I, the chromosome number will be reduced from diploid to haploid, with each daughter cell receiving one of the two homologous chromosomes for each of the 2 different chromosomes in this example:<\/p>\n<div id=\"attachment_324\" style=\"width: 414px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round1.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-324\" class=\"size-full wp-image-324\" src=\"https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round1.jpg\" alt=\"\" width=\"404\" height=\"725\" srcset=\"https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round1.jpg 404w, https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round1-167x300.jpg 167w\" sizes=\"auto, (max-width: 404px) 100vw, 404px\" \/><\/a><p id=\"caption-attachment-324\" class=\"wp-caption-text\">cells after meiosis I<\/p><\/div>\n<p>After meiosis II, the daughter cells each have a single copy of each chromosome, still having only one\u00a0<em>version<\/em> of each chromosome from the previous meiotic division:<\/p>\n<div id=\"attachment_325\" style=\"width: 828px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round2.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-325\" class=\"size-full wp-image-325\" src=\"https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round2.jpg\" alt=\"\" width=\"818\" height=\"723\" srcset=\"https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round2.jpg 818w, https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round2-300x265.jpg 300w, https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round2-768x679.jpg 768w, https:\/\/sites.owu.edu\/wolverton\/wp-content\/uploads\/sites\/54\/2012\/11\/round2-624x552.jpg 624w\" sizes=\"auto, (max-width: 818px) 100vw, 818px\" \/><\/a><p id=\"caption-attachment-325\" class=\"wp-caption-text\">cells after meiosis II<\/p><\/div>\n<h3>Comparison with Mitosis<\/h3>\n<ul>\n<li>mitosis compares most directly with meiosis II in that both result in the separation of sister chromatids<\/li>\n<li>mitosis always maintains the same number of <em>versions<\/em> of chromosomes (like editions of a book)<\/li>\n<li>meiosis I reduces chromosome number by half, meiosis II separates sister chromatids<\/li>\n<li>there is no intervening interphase between meiosis I and II<\/li>\n<\/ul>\n<h2>In-class Activities<\/h2>\n<h2>Questions for Practice<\/h2>\n<ul>\n<li>Draw or describe the process of meiosis, labeling each resultant cell with its ploidy level (diploid or haploid).<\/li>\n<li>Explain two ways in which meiosis results in greater genetic variation.<\/li>\n<\/ul>\n<p><!--:--><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Links Principles Module 38 Objectives Explain the similarities and differences between meiosis and mitosis Describe how meiosis produces greater genetic variation Key Points Features of meiosis synapsis: homologous chr pair form synaptonemal complex, binds hom. chrom. together composed of variant of cohesin crossing over: exchange of bits of DNA btw hom. chrom. results in recombination, [&hellip;]<\/p>\n","protected":false},"author":40,"featured_media":0,"parent":447,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-218","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/sites.owu.edu\/wolverton\/wp-json\/wp\/v2\/pages\/218","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.owu.edu\/wolverton\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sites.owu.edu\/wolverton\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sites.owu.edu\/wolverton\/wp-json\/wp\/v2\/users\/40"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.owu.edu\/wolverton\/wp-json\/wp\/v2\/comments?post=218"}],"version-history":[{"count":1,"href":"https:\/\/sites.owu.edu\/wolverton\/wp-json\/wp\/v2\/pages\/218\/revisions"}],"predecessor-version":[{"id":507,"href":"https:\/\/sites.owu.edu\/wolverton\/wp-json\/wp\/v2\/pages\/218\/revisions\/507"}],"up":[{"embeddable":true,"href":"https:\/\/sites.owu.edu\/wolverton\/wp-json\/wp\/v2\/pages\/447"}],"wp:attachment":[{"href":"https:\/\/sites.owu.edu\/wolverton\/wp-json\/wp\/v2\/media?parent=218"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}