Cell Cycle and Cell Division Control: Introduction

by Georgina Cornwall, PhD

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    00:01 Previously, you learned about cell communications.

    00:04 Now, we're going to take a look at how some of those communications manifest themselves in the cell cycle and its controls.

    00:11 By the end of this lecture, you should be able to describe the main events of each phase of the cell cycle as well as have an understanding of its checkpoints and illustrate how those work.

    00:22 In addition, you'll have some idea of how failure of these checkpoints, failure of these cell cycle controls could result in uncontrolled cell division or cancers.

    00:35 So let's begin by looking at the cell cycle itself. You're probably familiar with mitosis and interphase.

    00:43 Interphase is the green portion of this cell cycle. And mitosis and cytokinesis are in the blue portion.

    00:50 Mitosis and cytokinesis are a relatively short part of each cell's life.

    00:55 It spends most of its time in other portions of the cycle, or interphase.

    01:01 So, mitosis, cytokinesis. Right after mitosis and cytokinesis, the cell is half the size that it used to be and so it needs to grow to its regular size. So Gap 1 phase or growth phase 1 is about cell growth back to its normal size.

    01:17 Now if the cell is fated to divide again, then we might move forward in the cycle.

    01:24 However, most cells don't divide and then divide immediately again. They'll spend quite some time in the Gap 1 phase.

    01:32 For example, if we were looking at muscle tissue or neurons in the brain or fat cells, they're really not going to divide again.

    01:40 And so when a cell is not going to divide again, we might call it G0 even because they are not going to move all the way through the Gap 1 phase.

    01:50 Towards the end of the Gap 1 phase, we're beginning preparations for synthesis of DNA, getting ready to duplicate those chromosomes so that we have two copies in order to move into cell division and separate those copies into other cells.

    02:06 So in S phase, or synthesis phase, is where we have DNA replication occur.

    02:12 We're going to cover the details of DNA replication in a future lecture.

    02:16 But for now, once replication has occur, we have two copies of each chromosomes, we move into the G2 phase. And in G2, all the mechanisms that need to come into place for cell division are being produced by the cells. So G2 is completed, and the cells can then move into mitosis and cytokinesis and the cycle continues, with a pause perhaps in the G1 phase.

    About the Lecture

    The lecture Cell Cycle and Cell Division Control: Introduction by Georgina Cornwall, PhD is from the course Cell Cycle and Cell Division.

    Included Quiz Questions

    1. S phase
    2. Gap 1 phase
    3. Gap 2 phase
    4. Mitosis
    5. Cytokinesis
    1. G1 to S to G2 to mitosis to cytokinesis
    2. G1 to G2 to S to mitosis to cytokinesis
    3. G1 to S to G2 to cytokinesis to mitosis
    4. S to G1 to G2 to mitosis to cytokinesis
    5. Cytokinesis to mitosis to G2 to G1 to S

    Author of lecture Cell Cycle and Cell Division Control: Introduction

     Georgina Cornwall, PhD

    Georgina Cornwall, PhD

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