{"id":4490,"date":"2021-02-11T20:55:39","date_gmt":"2021-02-11T20:55:39","guid":{"rendered":"https:\/\/opentextbc.ca\/biology\/part\/introduction-to-reproduction-at-the-cellular-level\/"},"modified":"2021-03-04T00:10:09","modified_gmt":"2021-03-04T00:10:09","slug":"introduction-to-reproduction-at-the-cellular-level","status":"publish","type":"part","link":"https:\/\/opentextbc.ca\/biology\/part\/introduction-to-reproduction-at-the-cellular-level\/","title":{"raw":"Chapter 6: Introduction to Reproduction at the Cellular Level","rendered":"Chapter 6: Introduction to Reproduction at the Cellular Level"},"content":{"raw":"<figure id=\"fs-id2061417\" class=\"splash\"><figcaption><\/figcaption><\/figure>\n<figure class=\"splash\">\n\n[caption id=\"attachment_169\" align=\"aligncenter\" width=\"800\"]<a href=\"http:\/\/opentextbc.ca\/biology\/wp-content\/uploads\/sites\/96\/2015\/02\/Figure_06_00_01abc.jpg\"><img class=\"wp-image-169\" src=\"https:\/\/opentextbc.ca\/biology\/wp-content\/uploads\/sites\/96\/2015\/08\/Figure_06_00_01abc-1024x2982-1.jpg\" alt=\"Image A shows two conjoined cells forming a dumbbell shape; the fertilization envelope has been removed so that the mesh-like outer layer can be seen. Image B shows the sea urchin embryo when it has divided into 16 conjoined cells; the overall shape is rounder than in image A. Image C shows a \u201cwater melon\u201d sea urchin which appears as a peach-colored ball covered in white protruding spines.\" width=\"800\" height=\"233\"><\/a> Figure 6.1 A sea urchin begins life as a single cell that (a) divides to form two cells, visible by scanning electron microscopy. After four rounds of cell division, (b) there are 16 cells, as seen in this SEM image. After many rounds of cell division, the individual develops into a complex, multicellular organism, as seen in this (c) mature sea urchin. (credit a: modification of work by Evelyn Spiegel, Louisa Howard; credit b: modification of work by Evelyn Spiegel, Louisa Howard; credit c: modification of work by Marco Busdraghi; scale-bar data from Matt Russell)[\/caption]\n\n&nbsp;<\/figure>\n<p id=\"fs-id1612560\">The individual sexually reproducing organism\u2014including humans\u2014begins life as a fertilized egg, or zygote. Trillions of cell divisions subsequently occur in a controlled manner to produce a complex, multicellular human. In other words, that original single cell was the ancestor of every other cell in the body. Once a human individual is fully grown, cell reproduction is still necessary to repair or regenerate tissues. For example, new blood and skin cells are constantly being produced. All multicellular organisms use cell division for <em>growth<\/em>, and in most cases, the <em>maintenance<\/em> and <em>repair<\/em> of cells and tissues. Single-celled organisms use cell division as their method of reproduction.<\/p>\n\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\n<h3 class=\"textbox__title\"><em>Search for Key Points in Chapter 6<\/em><\/h3>\n<\/header>\n<div class=\"textbox__content\">\n\n[h5p id=\"37\"]\n\n<\/div>\n<\/div>","rendered":"<figure id=\"fs-id2061417\" class=\"splash\"><figcaption><\/figcaption><\/figure>\n<figure class=\"splash\">\n<figure id=\"attachment_169\" aria-describedby=\"caption-attachment-169\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><a href=\"http:\/\/opentextbc.ca\/biology\/wp-content\/uploads\/sites\/96\/2015\/02\/Figure_06_00_01abc.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-169\" src=\"https:\/\/opentextbc.ca\/biology\/wp-content\/uploads\/sites\/96\/2015\/08\/Figure_06_00_01abc-1024x2982-1.jpg\" alt=\"Image A shows two conjoined cells forming a dumbbell shape; the fertilization envelope has been removed so that the mesh-like outer layer can be seen. Image B shows the sea urchin embryo when it has divided into 16 conjoined cells; the overall shape is rounder than in image A. Image C shows a \u201cwater melon\u201d sea urchin which appears as a peach-colored ball covered in white protruding spines.\" width=\"800\" height=\"233\" \/><\/a><figcaption id=\"caption-attachment-169\" class=\"wp-caption-text\">Figure 6.1 A sea urchin begins life as a single cell that (a) divides to form two cells, visible by scanning electron microscopy. After four rounds of cell division, (b) there are 16 cells, as seen in this SEM image. After many rounds of cell division, the individual develops into a complex, multicellular organism, as seen in this (c) mature sea urchin. (credit a: modification of work by Evelyn Spiegel, Louisa Howard; credit b: modification of work by Evelyn Spiegel, Louisa Howard; credit c: modification of work by Marco Busdraghi; scale-bar data from Matt Russell)<\/figcaption><\/figure>\n<p>&nbsp;<\/figure>\n<p id=\"fs-id1612560\">The individual sexually reproducing organism\u2014including humans\u2014begins life as a fertilized egg, or zygote. Trillions of cell divisions subsequently occur in a controlled manner to produce a complex, multicellular human. In other words, that original single cell was the ancestor of every other cell in the body. Once a human individual is fully grown, cell reproduction is still necessary to repair or regenerate tissues. For example, new blood and skin cells are constantly being produced. All multicellular organisms use cell division for <em>growth<\/em>, and in most cases, the <em>maintenance<\/em> and <em>repair<\/em> of cells and tissues. Single-celled organisms use cell division as their method of reproduction.<\/p>\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\"><em>Search for Key Points in Chapter 6<\/em><\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<div id=\"h5p-37\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-37\" class=\"h5p-iframe\" data-content-id=\"37\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Introduction to Reproduction at the Cellular Level Ch 6 Search for key points\"><\/iframe><\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"parent":0,"menu_order":9,"template":"","meta":{"pb_part_invisible":false,"pb_part_invisible_string":""},"contributor":[],"license":[],"class_list":["post-4490","part","type-part","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/opentextbc.ca\/biology\/wp-json\/pressbooks\/v2\/parts\/4490","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opentextbc.ca\/biology\/wp-json\/pressbooks\/v2\/parts"}],"about":[{"href":"https:\/\/opentextbc.ca\/biology\/wp-json\/wp\/v2\/types\/part"}],"version-history":[{"count":2,"href":"https:\/\/opentextbc.ca\/biology\/wp-json\/pressbooks\/v2\/parts\/4490\/revisions"}],"predecessor-version":[{"id":5222,"href":"https:\/\/opentextbc.ca\/biology\/wp-json\/pressbooks\/v2\/parts\/4490\/revisions\/5222"}],"wp:attachment":[{"href":"https:\/\/opentextbc.ca\/biology\/wp-json\/wp\/v2\/media?parent=4490"}],"wp:term":[{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbc.ca\/biology\/wp-json\/wp\/v2\/contributor?post=4490"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbc.ca\/biology\/wp-json\/wp\/v2\/license?post=4490"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}