{"id":1344,"date":"2020-08-06T21:10:22","date_gmt":"2020-08-06T21:10:22","guid":{"rendered":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/"},"modified":"2021-01-31T22:03:19","modified_gmt":"2021-01-31T21:03:19","slug":"cell-cycle","status":"publish","type":"page","link":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/","title":{"rendered":"Cell Cycle"},"content":{"rendered":"\n

Basics of the Cell Cycle<\/h4>\n<\/span>\n\n\n

The cell cycle describes the lifecycle of cells through a series of events leading to duplication of their DNA (DNA replication) and division of cytoplasm and organelles to produce two daughter cells from a single mother cell. It is necessary for the normal development of the cell and the organism as a whole.<\/div><\/p>\n\n\n\n
\"\"<\/a>
The cell cycle<\/strong> (Credit: Kelvinsong, CC BY-SA 4.0)<\/figcaption><\/figure><\/div>\n\n\n<\/span>\n

Stages of the Cell Cycle<\/h3>\n<\/span>\n\n\n

The cell cycle can be divided into 5 stages:<\/p>\n\n\n\n

  1. G1 phase<\/li>
  2. S phase<\/li>
  3. G2 phase<\/li>
  4. M phase<\/li>
  5. Cytokinesis<\/li><\/ol>\n\n\n\n

    The first 3 phases are generally classified as interphase.<\/p>\n\n\n\n

    There is a G0 phase<\/strong> which is a resting stage as the cells here undergo no cell division. It is usually between the cytokinesis and G1 stages.<\/p>\n\n\n<\/span>\n

    G1 phase<\/h4>\n<\/span>\n\n\n

    The G1 phase<\/strong> can also be called the preparatory phase. Here a growth factor will begin a signaling cascade that will initiate the cell cycle. The cell also gathers materials (nutrients) necessary for the next step.<\/p>\n\n\n<\/span>\n

    S phase<\/h4>\n<\/span>\n\n\n

    The S phase<\/strong> involves the replication of DNA where new genetic material is synthesized in a semi-conservative manner. The centrioles are also replicated in this phase in a semi-conservative manner.<\/p>\n\n\n<\/span>\n

    G2 phase<\/h4>\n<\/span>\n\n\n

    The G2 phase<\/strong> is also another preparatory phase where the cell gathers the necessary nutrients for the next phase of the cell cycle. Here the other cell organelles are also replicated.<\/p>\n\n\n<\/span>\n

    M phase<\/h4>\n<\/span>\n\n\n

    The M phase<\/strong> can be meiosis or mitosis (depending on which type of cell the division is occurring in; somatic or germline cell ) and has 5 sub-stages. It involves the equal distribution of the replicated DNA  into the 2 daughter nuclei.<\/p>\n\n\n<\/span>\n

    Cytokinesis<\/h4>\n<\/span>\n\n\n

    Cytokinesis<\/strong> involves the separation of the cytoplasm and cellular organelles of the 2 daughter cells by the formation of an actin ring.<\/p>\n\n\n<\/span>\n

    Microtubules<\/h3>\n<\/span>\n\n\n

    Microtubules are microscopic tubes present in the mitotic spindle (all emanating from the centrosomes), that serve to push and pull the sister chromatids apart toward opposite spindle poles. There are three types of microtubules:<\/p>\n\n\n\n

    1. Kinetochore microtubules <\/strong>are attached to the kinetochore of a chromosome. The kinetochore is a multi-protein complex that attaches the chromosome to the kinetochore microtubules. There are two per chromosome; one for each sister chromatid.<\/li>
    2. Polar microtubules<\/strong> are microtubules from opposite poles that do not attach to the kinetochores but overlap at the midpoint between the two poles and work to push the spindle poles apart via motor proteins (motor proteins are proteins that can travel along the length of a microtubule in an energy-dependent fashion).<\/li>
    3. Astral microtubules <\/strong>anchor the spindle poles to the cell membrane. They point away from the spindle equator and are attached to the cell’s cortex.<\/li><\/ol>\n\n\n\n
      \"\"<\/a>
      Types of microtubules<\/strong> (Credit: Lordjuppiter, CC BY-SA 3.0)<\/figcaption><\/figure><\/div>\n\n\n<\/span>\n

      Regulation of the Cell Cycle<\/h3>\n<\/span>\n\n\n

      The cell cycle can be regulated extrinsically by limiting or removing of the growth factors\/signals or intrinsically by its checkpoints. The cell cycle has 4 checkpoints;<\/p>\n\n\n\n

      1. The G1\/S phase checkpoint<\/strong> which ensures that the correct DNA is available for replication, preventing the replication of damaged DNA. It also ensures that there are enough nutrients and growth factors for replication.<\/li>
      2. The S phase checkpoint <\/strong>which checks for DNA damage during replication. But unlike the other checkpoints, it does not inhibit movement into the next stage of DNA replication. Instead, it reduces the amount of DNA that progresses to the next stage. It is more involved in tolerating and accommodating damage than repairing it.<\/li>
      3. The G2\/M phase checkpoint<\/strong> that ensures that DNA has been replicated properly in the S phase. It prevents damaged DNA from going into the M phase. It also checks cell size.<\/li>
      4. The Metaphase\/Anaphase checkpoint<\/strong> that ensures that chromosomes are properly lined up at the equator and joined to the spindle fibres before segregation.<\/li><\/ol>\n\n\n<\/span>\n

        Pathologies of the Cell Cycle<\/h3>\n<\/span>\n\n\n

        The cell cycle has to be regulated properly as loss of checkpoints can result in various abnormalities such as non-reciprocal crossing over and non-disjunction (discussed in detail in the Cytogenetics: Chromosomal aberrations course)<\/em> and uncontrolled cell division (discussed in detail in the  Genetics 2: Oncogenetics course).<\/em><\/p>\n<\/span>

        Basics of the Cell Cycle<\/h4>

        Stages of the Cell Cycle<\/h3>

        G1 phase<\/h4>

        S phase<\/h4>

        G2 phase<\/h4>

        M phase<\/h4>

        Cytokinesis<\/h4>

        Microtubules<\/h3>

        Regulation of the Cell Cycle<\/h3>

        Pathologies of the Cell Cycle<\/h3><\/div>","protected":false},"excerpt":{"rendered":"

        Basics of the Cell Cycle Stages of the Cell Cycle The cell cycle can be divided into 5 stages: G1 phase S phase G2 phase M phase Cytokinesis The first 3 phases are generally classified as interphase. There is a G0 phase which is a resting stage as the cells here undergo no cell division. […]<\/p>\n","protected":false},"author":143,"featured_media":0,"parent":1343,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1344","page","type-page","status-publish","hentry"],"yoast_head":"\nCell Cycle – Meddists<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"4 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/medical-genetics\\\/cell-cycle\\\/\",\"url\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/medical-genetics\\\/cell-cycle\\\/\",\"name\":\"Cell Cycle – Meddists\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/medical-genetics\\\/cell-cycle\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/medical-genetics\\\/cell-cycle\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/meddists.com\\\/wp-content\\\/uploads\\\/2020\\\/02\\\/1054px-Animal_cell_cycle-en.svg1_-600x583.png\",\"datePublished\":\"2020-08-06T21:10:22+00:00\",\"dateModified\":\"2021-01-31T21:03:19+00:00\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/medical-genetics\\\/cell-cycle\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/medical-genetics\\\/cell-cycle\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/medical-genetics\\\/cell-cycle\\\/#primaryimage\",\"url\":\"https:\\\/\\\/meddists.com\\\/wp-content\\\/uploads\\\/2020\\\/02\\\/1054px-Animal_cell_cycle-en.svg1_-600x583.png\",\"contentUrl\":\"https:\\\/\\\/meddists.com\\\/wp-content\\\/uploads\\\/2020\\\/02\\\/1054px-Animal_cell_cycle-en.svg1_-600x583.png\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/medical-genetics\\\/cell-cycle\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"http:\\\/\\\/meddists.com\\\/learn\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Pre-clinical\",\"item\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Medical Genetics\",\"item\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/medical-genetics\\\/\"},{\"@type\":\"ListItem\",\"position\":4,\"name\":\"Cell Cycle\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/#website\",\"url\":\"https:\\\/\\\/meddists.com\\\/learn\\\/\",\"name\":\"Meddists\",\"description\":\"Let's Get Studying\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/meddists.com\\\/learn\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Cell Cycle – Meddists","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/","twitter_misc":{"Est. reading time":"4 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/","url":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/","name":"Cell Cycle – Meddists","isPartOf":{"@id":"https:\/\/meddists.com\/learn\/#website"},"primaryImageOfPage":{"@id":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/#primaryimage"},"image":{"@id":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/#primaryimage"},"thumbnailUrl":"https:\/\/meddists.com\/wp-content\/uploads\/2020\/02\/1054px-Animal_cell_cycle-en.svg1_-600x583.png","datePublished":"2020-08-06T21:10:22+00:00","dateModified":"2021-01-31T21:03:19+00:00","breadcrumb":{"@id":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/#primaryimage","url":"https:\/\/meddists.com\/wp-content\/uploads\/2020\/02\/1054px-Animal_cell_cycle-en.svg1_-600x583.png","contentUrl":"https:\/\/meddists.com\/wp-content\/uploads\/2020\/02\/1054px-Animal_cell_cycle-en.svg1_-600x583.png"},{"@type":"BreadcrumbList","@id":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cell-cycle\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"http:\/\/meddists.com\/learn\/"},{"@type":"ListItem","position":2,"name":"Pre-clinical","item":"https:\/\/meddists.com\/learn\/pre-clinical\/"},{"@type":"ListItem","position":3,"name":"Medical Genetics","item":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/"},{"@type":"ListItem","position":4,"name":"Cell Cycle"}]},{"@type":"WebSite","@id":"https:\/\/meddists.com\/learn\/#website","url":"https:\/\/meddists.com\/learn\/","name":"Meddists","description":"Let's Get Studying","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/meddists.com\/learn\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"}]}},"_links":{"self":[{"href":"https:\/\/meddists.com\/learn\/wp-json\/wp\/v2\/pages\/1344","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/meddists.com\/learn\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/meddists.com\/learn\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/meddists.com\/learn\/wp-json\/wp\/v2\/users\/143"}],"replies":[{"embeddable":true,"href":"https:\/\/meddists.com\/learn\/wp-json\/wp\/v2\/comments?post=1344"}],"version-history":[{"count":2,"href":"https:\/\/meddists.com\/learn\/wp-json\/wp\/v2\/pages\/1344\/revisions"}],"predecessor-version":[{"id":4211,"href":"https:\/\/meddists.com\/learn\/wp-json\/wp\/v2\/pages\/1344\/revisions\/4211"}],"up":[{"embeddable":true,"href":"https:\/\/meddists.com\/learn\/wp-json\/wp\/v2\/pages\/1343"}],"wp:attachment":[{"href":"https:\/\/meddists.com\/learn\/wp-json\/wp\/v2\/media?parent=1344"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}