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Cell Division and Mitosis. Chapter 10. 10.1 The Cycle of Cell Growth and Division: An Overview. The products of mitosis are genetic duplicates of the dividing cell Chromosomes are the genetic units divided by mitosis. Mitotic Cell Division. DNA replication

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10 1 the cycle of cell growth and division an overview
10.1 The Cycle of Cell Growth and Division: An Overview
  • The products of mitosis are genetic duplicates of the dividing cell
  • Chromosomes are the genetic units divided by mitosis
mitotic cell division
Mitotic Cell Division
  • DNA replication
  • Equal separation (segregation) of replicated DNA molecules
  • Delivery to daughter cells
    • Two new cells, same information as parent cell
mitosis
Mitosis
  • Mitosis is the basis for
    • Growth and maintenance of body mass in multicelled eukaryotes
    • Reproduction of many single-celled eukaryotes
chromosomes
Chromosomes
  • DNA of eukaryotic cells is divided among individual, linear chromosomes
    • Located in cell nucleus
  • Ploidy of a cell or species
    • Diploid (2n)
    • Haploid (n)
eukaryotic chromosomes
Eukaryotic Chromosomes

Fig. 10-2, p. 203

sister chromatids
Sister Chromatids
  • DNA replication and duplication of chromosomal proteins produces two exact copies (sister chromatids)
  • Chromosome segregation occurs during cell division
10 2 the mitotic cell cycle
10.2 The Mitotic Cell Cycle
  • Interphase extends from the end of one mitosis to the beginning of the next mitosis
  • After interphase, mitosis proceeds in five stages
  • Cytokinesis completes cell division by dividing the cytoplasm between daughter cells
10 2 cont
10.2 (cont.)
  • The mitotic cell cycle is significant for both development and reproduction
  • Mitosis varies in detail, but always produces duplicate nuclei
mitotic cell cycle
Mitotic Cell Cycle
  • Includes mitosis and interphase
  • Mitosis occurs in five stages
    • Prophase
    • Prometaphase
    • Metaphase
    • Anaphase
    • Telophase
the cell cycle
The Cell Cycle

Fig. 10-3, p. 203

interphase
Interphase

Fig. 10-4a (1), p. 204

stage 1 prophase
Stage 1: Prophase
  • Chromosomes condense into short rods
  • Spindle forms in the cytoplasm
prophase
Prophase

Fig. 10-4a (2), p. 204

stage 2 prometaphase
Stage 2: Prometaphase
  • Nuclear envelope breaks down
    • Spindle enters former nuclear area
    • Sister chromatids of each chromosome connect to opposite spindle poles
  • Kinetochore of each chromatid attaches to the spindle microtubules
prometaphase
Prometaphase

Fig. 10-4a, p. 204

stage 3 metaphase
Stage 3: Metaphase
  • Spindle is fully formed
  • Chromosomes align at metaphase plate
    • Moved by spindle microtubules
metaphase
Metaphase

Fig. 10-4b, p. 204

stage 4 anaphase
Stage 4: Anaphase
  • Spindle separates sister chromatids and moves them to opposite spindle poles
  • Chromosome segregation is complete
anaphase
Anaphase

Fig. 10-4b, p. 204

stage 5 telophase
Stage 5: Telophase
  • Chromosomes decondense
    • Return to extended state typical of interphase
  • New nuclear envelope forms around chromosomes
telophase
Telophase

Fig. 10-4b, p. 204

mitosis1
Mitosis

Fig. 10-5, p. 206

cytokinesis
Cytokinesis
  • Division of cytoplasm completes cell division
  • Produces two daughter cells
    • Each daughter nucleus produced by mitosis
cytokinesis in animal cells
Cytokinesis in Animal Cells
  • Proceeds by furrowing
    • Band of microfilaments just under the plasma membrane contracts
    • Gradually separates cytoplasm into two parts
cytokinesis by furrowing
Cytokinesis by Furrowing

Fig. 10-8, p. 208

plant cytokinesis
Plant Cytokinesis
  • Cell wall material is deposited along the plane of the former spindle midpoint
  • Deposition continues until a continuous new wall (cell plate) separates daughter cells
10 3 formation and action of the mitotic spindle
10.3 Formation and Action of the Mitotic Spindle
  • Animals and plants form spindles in different ways
  • Mitotic spindles move chromosomes by a combination of two mechanisms
spindle formation
Spindle Formation
  • In animal cells
    • Centrosome divides, the two parts move apart
    • Microtubules of the spindle form between them
  • In plant cells with no centrosome
    • Spindle microtubules assemble around the nucleus
in the spindle
In the Spindle
  • Kinetochore microtubules
    • Run from poles to kinetochores of chromosomes
  • Nonkinetochore microtubules
    • Run from poles to a zone of overlap at the spindle midpoint without connecting to chromosomes
a fully developed spindle
A Fully Developed Spindle

Fig. 10-11, p. 210

during anaphase
During Anaphase
  • Kinetochores move along kinetochore microtubules
    • Pulling chromosomes to the poles
  • Nonkinetochore microtubules slide over each other
    • Pushing the poles farther apart
anaphase spindle movements
Anaphase Spindle Movements

Fig. 10-12, p. 211

kinetochore movement
Kinetochore Movement

Fig. 10-13, p. 211

10 4 cell cycle regulation
10.4 Cell Cycle Regulation
  • Cyclins and cyclin-dependent kinases
    • Internal controls that directly regulate cell division
  • Internal checkpoints
    • Stop cell cycle if stages are incomplete
  • External controls
    • Coordinate mitotic cell cycle of individual cells within overall activities of the organism
cell cycle control 1
Cell Cycle Control (1)
  • Complexes of cyclin and a cyclin-dependent protein kinase (CDK)
    • Directly control cell cycle
  • CDK
    • Is activated when combined with a cyclin
    • Adds phosphate groups to target proteins, activating them
cell cycle control 2
Cell Cycle Control (2)
  • Activated proteins trigger the cell to progress to the next cell cycle stage
  • Each major stage of the cell cycle
    • Begins with activation of one or more cyclin/CDK complexes
    • Ends with deactivation of complexes by breakdown of cyclins
cyclin cdk control
Cyclin/CDK Control

Fig. 10-15, p. 214

internal controls
Internal Controls
  • Important internal controls create checkpoints
    • Ensure that the reactions of one stage are complete before cycle proceeds to next stage
external controls
External Controls
  • Based on surface receptors that recognize and bind signals
    • Peptide hormones and growth factors
    • Surface groups on other cells
    • Molecules of the extracellular matrix
  • Binding triggers internal reactions that speed, slow, or stop cell division
cancer
Cancer
  • Control of cell division is lost
    • Cells divide continuously and uncontrollably
    • Form rapidly growing mass of cells that interferes with body functions
  • Cancer cells break loose from their original tumor (metastasize)
    • Form additional tumors in other parts of the body
tumor cells
Tumor Cells

Fig. 10-16, p. 215