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Major Objectives
1. What are the two key roles of mitotic cell division?
2. Understand the different phases of the mitotic cell cycle and the regulation of the cell cycle (checkpoints)
3. Understand the phases of mitosis
4. Know how cytokinesis differs between plant and animal cells
Two key roles of mitotic cell division
1. Cell division functions in reproduction, growth, and repair
Interphase (4 subphases)
G0) Phase-Cell leaves cell cycle.
G1 Phase-Centered on growth.
Cells increase in size, produce RNA and synthesize protein.
(G1 Checkpoint) ensures that everything is ready for DNA synthesis.
Interphase (4 subphases)
S Phase Synthesis-chromosomes copied.
·To produce two similar daughter cells, the complete DNA instructions in the cell must be duplicated. DNA replication occurs
Interphase (4 subphases)
G2 Phase-Second Gap Phase. Cell completes preparations for cell division.
·Cell will continue to grow and produce new proteins.
(G2 Checkpoint) to determine if the cell can now proceed to enter M (mitosis) and divide.
Cell growth and protein production stop at this stage in the cell cycle.
Division into two similar daughter cells.
(Metaphase Checkpoint) that ensures the cell is ready to complete cell division.
Mitosis or M Phase:
Cytokinesis
-Division of the cytoplasm after mitosis Animals-Cleavage furrow in the cell surface forms and the ring pinches the cell in twoPlants-Cell plate is formed during telophase and the plate enlarges until its membranes fuse with plasma membrane
Cell prepares for division by:
•replicating DNA and organelles •increasing cell size
Plant Interphase
Plant Prophase
Cell prepares for nuclear division by:•condensing DNA into movable packages called chromosomes
Plant Metaphase
Cell prepares chromosomes for division by:•aligning chromosomes at cell equator •attaching spindle fibers from each new daughter cell pole to each chromosome at the centromere
Plant Anaphase
Chromosomes divide:•spindle fibers pull chromosomes apart •one-half of each chromosome (chromatid) moves to a new daughter cell
Plant Telophase
Cytoplasm divides:•DNA de-condenses and two nuclei form •new cell wall (cell plate) appears between the two nuclei to form two new daughter cells
TelophaseCytokinesis begins (cleavage furrow). Nuclear envelope begins to reform around single chromatin chromosomes