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Cell Cycle and Mitosis

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Cell Cycle and Mitosis 12.1 Cell Cycle What is the cell cycle? Repeating series of events Five stages Interphase (3 parts) G1 S G2 M phase (2 parts) Mitosis ... – PowerPoint PPT presentation

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Title: Cell Cycle and Mitosis


1
Cell Cycle and Mitosis
  • 12.1 Cell Cycle

2
What is the cell cycle?
  • Repeating series of events
  • Five stages
  • Interphase (3 parts)
  • G1
  • S
  • G2
  • M phase (2 parts)
  • Mitosis
  • Cytokinesis

3
What happens in Interphase?
  • G1
  • Normal growth
  • Recovery from last mitotic division
  • S
  • Replication of chromatids
  • G2
  • Synthesis of proteins for mitosis

4
Cell Cycle and Mitosis
  • 12.2 M phase Mitosis and cytokinesis

5
What happens during the M phase?
  • Mitosis
  • Prokaryotes undergo binary fission instead
  • Cytokinesis

6
What is a chromosome?
  • Length of DNA with genes and noncoding regions
  • Highly condensed version of chromatin
  • Heterochromatin vs. euchromatin

7
What is mitosis?
  • Division of nuclear material
  • Duplicated chromosomes are split
  • This creates unduplicated chromosomes
  • Chromosome terminology
  • Sister chromatids
  • Kinetechore
  • Centromere
  • Diploid (2n) vs. haploid (1n)

8
What are the stages of mitosis?
  • Prophase
  • Prometphase
  • Metaphase
  • Anaphase
  • Telophase

9
What happens in prophase?
  • Nuclear envelope disappears
  • Centrioles move apart
  • Nucleous disappears
  • Chromatin condenses to form chromosomes
  • Recall that these are duplicated

10
What happens during prometaphase?
  • Kinetechores appear
  • Spindles attach
  • Polar spindle fibers extend and overlap

11
What happens during metaphase?
  • Duplicated chromosomes align along metaphase plate

12
What happens during anaphase?
  • Sister chromatids pulled apart
  • Chromosomes are now unduplicated

13
What happens during telophase?
  • Reverse of prophase
  • Cleavage furrow develops in animal cells

14
What is the second part of the M phase?
  • Cytokinesis
  • Cytoplasmic division
  • Animal cells
  • Contractile ring
  • Plant cells
  • Cell plate

15
Cell Cycle and Mitosis
  • 12.3 Cell cycle control and cancer

16
Why do cells undergo mitosis?
  • Repair and replacement
  • Apoptosis of somatic cells
  • blebbing
  • Stem cells
  • Serve as reservoir for replacing old cells

17
What controls the cell cycle?
  • Checkpoints
  • G1
  • Apoptosis if DNA is damaged
  • G2
  • M

18
What is cancer?
  • Uncontrolled cell growth
  • Characteristics
  • Neoplasms (tumors)
  • Benign vs. malignant
  • Angiogenesis
  • Metastasis
  • Abnormal nuclei
  • Undifferentiated (anaplasia)
  • Lack contact inhibition
  • No apoptosis

19
How does cancer occur?
  • Mutations of cell repair genes
  • Activation of telomerase
  • Mutations of either/both
  • Proto-oncogenes
  • Become oncogenes
  • Tumor suppressor cells

20
What are proto-oncogenes?
  • gas pedal of cell division
  • Mutated? oncogene
  • Examples
  • ras genes
  • rasN (leukemia)
  • BRCA1

21
What are tumor suppressor genes?
  • Brake pedal of cell division
  • If mutated ? loss of cell cycle control
  • Examples
  • p53 gene
  • RB gene
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