Mitosis

Mitosis - THE CELL CYCLE CHAPTER 19 LECTURE 20 1. Cell...

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THE CELL CYCLE CHAPTER 19 LECTURE 20
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1. Cell Cycle Introduction: - Cell cycle is composed of two phases: M phase and Interphase - M PHASE: the process of cell division; two overlapping processes. * Mitosis (karyokinesis, nuclear division): i. Two genetically identical daughter nuclei produced from one parent nucleus. ii. Five overlapping sub-phases: prophase, prometaphase, metaphase, anaphase, and telophase * Cytokinesis : cytoplasmic division. - INTERPHASE: G 1 , (G 0 ), S, and G 2 sub-phases, growth phase of the cell cycle.
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2. Interphase: - Longest phase (~90%); cell appears deceptively inactive - G 1 Phase: The first ‘gap’ stage after the M phase * What happens? i. Cell growth ii. Gene transcription iii. Protein synthesis iv. DNA repair v. Monitors/Responds to external (nutrients, signaling molecules) vi. Organelles divide * G 1 and G 2 play major role to ensure conditions are suitable and preparations are complete before cell commits major investments in proceeding to S and M phases ( checkpoints ) S phase
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-G 0 Phase: Extended 'resting' state; cell's entry into S phase is delayed for days, weeks or years. Many cells remain permanently in G 0 (e.g., nerve cells, skeletal muscle cells, mature tissues). - S (Synthesis) Phase: * What happens? i. Replication of DNA but not separation ii. Replication of centrosomes but not separation
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-G 2 Phase: The second ‘gap’ stage * What happens? i. Growth continues as in G 1 ii. Final preparations to enter M phase (cell checks for size, DNA replication is complete). There are two main checkpoints in the eukaryotic cell cycle = points that determine whether or not the cell proceeds to the next phase of the cycle. The determination is based on external and internal conditions and factors (e.g., available nutrients, signaling molecules, DNA replication, DNA damage, cell size).
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This note was uploaded on 10/10/2009 for the course BIO 351 taught by Professor Oberstein during the Spring '08 term at ASU.

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Mitosis - THE CELL CYCLE CHAPTER 19 LECTURE 20 1. Cell...

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