cell cycle and mitosis
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Cell Cycle and Mitosis. 9.1 Cell Cycle. What is the cell cycle?. Repeating series of events Five stages Interphase (3 parts) G 1 S G 2 M phase (2 parts) Mitosis Cytokinesis. What happens in Interphase?. G 1 Normal growth Recovery from last mitotic division S - PowerPoint PPT PresentationTRANSCRIPT
Cell Cycle and Mitosis
9.1 Cell Cycle
What is the cell cycle? Repeating series of events Five stages Interphase (3 parts)
G1
S G2
M phase (2 parts) Mitosis Cytokinesis
What happens in Interphase? G1
Normal growth Recovery from last
mitotic division S
Replication of chromatids
G2
Synthesis of proteins for mitosis
Cell Cycle and Mitosis
9.2 M phase: Mitosis and cytokinesis
What happens during the M phase? Mitosis
Prokaryotes undergo binary fission instead
Cytokinesis
What is a chromosome? Length of DNA with
genes and noncoding regions
Highly condensed version of chromatin Heterochromatin vs.
euchromatin
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)
What are the stages of mitosis? Prophase Prometphase Metaphase Anaphase Telophase
What happens in prophase? Nuclear envelope
disappears Centrioles move apart Nucleous disappears Chromatin condenses to
form chromosomes Recall that these are
duplicated
What happens during prometaphase? Kinetechores appear Spindles attach Polar spindle fibers extend and overlap
What happens during metaphase? Duplicated chromosomes align along
metaphase plate
What happens during anaphase? Sister chromatids pulled apart Chromosomes are now
unduplicated
What happens during telophase? Reverse of prophase Cleavage furrow develops in animal
cells
What is the second part of the M phase? Cytokinesis
Cytoplasmic division Animal cells
Contractile ring Plant cells
Cell plate
Cell Cycle and Mitosis
9.3 Cell cycle control and cancer
Why do cells undergo mitosis? Repair and replacement
Apoptosis of somatic cells blebbing
Stem cells Serve as reservoir for replacing old cells
What controls the cell cycle? Checkpoints
G1
Apoptosis if DNA is damaged
G2
M
What is cancer? Uncontrolled cell growth Characteristics
Neoplasms (tumors) Benign vs. malignant Angiogenesis Metastasis Abnormal nuclei Undifferentiated (anaplasia) Lack contact inhibition No apoptosis
How does cancer occur? Mutations of cell
repair genes Activation of
telomerase Mutations of
either/both Proto-oncogenes
Become oncogenes Tumor suppressor
cells
What are proto-oncogenes? “gas pedal” of cell
division Mutated oncogene Examples
ras genes rasN (leukemia) BRCA1
What are tumor suppressor genes? Brake pedal of cell
division If mutated loss of
cell cycle control Examples
p53 gene RB gene