Cell Cycle Chapter 17.pdf - find more resources at...

  • Ryerson University
  • BLG 311
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  • AlexeyKharkov
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Chapter 17 Cell Cycle Overview of the cell cycle Overview of the cell cycle: Four Stages The most basic function of the cell cycle is to duplicate DNA and divide and create two identical daughter cells There are two major phases in cell cycle, the S and M phase Chromosome duplication occurs in the S (DNA Synthesis) phase, takes 10 to 12 hours After S phase, mitosis begins, which is the separation of chromosomes Mitosis has two phases; the nuclear division and cytoplasmic division Nuclear division is where the copied chromosomes are distributed into the daughter nuclei Cytoplasmic division or cytokinesis is when the cell itself divides into two At the end of the S phase, copied DNA and Chromosomes are held together by a protein linkage Prophase o DNA molecules disentangled and condensed into pairs, called sister chromatids o When nuclear envelop disassembles, the chromatids attach to the mitotic spindle (bipolar array of microtubules) o Chromatids attached to the opposite poles of the spindle, aligning in the center Metaphase to Anaphase o Chromatids are aligned and the destruction of the cohesion at the start of anaphase separates the chromatids Telophase o Chromosomes are packaged into separate nuclei at the telophase Cytokinesis then separates the cell into two, Cells require gap phases, which allows the cell to have time to grow and double their mass of proteins and organelles for duplication The first gap phase occurs between M and S phase, and the second gap occurs between S and mitosis Thus there are four phases; G1, S, G2 and M which happens in sequence, all of which occurs in Interphase. Gaps also allow the cell to monitor the internal and external environments to ensure proper conditions G-0 or the zero gap, is the resting stage, where the cell division is paused Overview of the cell cycle: Cell Cycle Control The control is similar in all Eucaryotes A protein that regulates control can be transferred from a human cell to a yeast cell and still function properly This can be used to study the protein find more resources at oneclass.com find more resources at oneclass.com

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