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The Cell Cycle. Mitosis: cell division that results in duplicate copy of an original cell containing the exact amount of genetic information. Happens in all somatic cells A cell’s total inherited amount of DNA is called its genome. The Cell Cycle. Interphase Mitosis Cytokinesis
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The Cell Cycle • Mitosis: cell division that results in duplicate copy of an original cell containing the exact amount of genetic information. • Happens in all somatic cells • A cell’s total inherited amount of DNA is called its genome.
The Cell Cycle • Interphase Mitosis Cytokinesis • Interphase: the growth phase in which cells make new molecules to increase its volume and mass • Further subdivided into the G1, S, and G2 phases • G1 phase: Gap 1 Rapid growth and metabolic activity • S phase: Synthesis phase DNA synthesis and replication • G2 phase: Gap 2 Centrioles replicate, cell prepares for cell division
Mitosis • Division of the cell’s nucleus where the daughter cells receive the exact number of chromosomes and genetic makeup as the parent cell • Consists of the four phases: prophase, metaphase, anaphase, telophase
Stages of Mitosis • (Interphase) • Prophase • Metaphase • Anaphase • Telophase These 5 stages can also be subdivided into early and late stages. ex: Early telophase, late telophase
Interphase • During this time, the nucleus is NOT actively dividing • The growth phase in which cells make new molecules to increase its volume and mass • Chromosomes are spread out in a delicate network called chromatin • Replication of chromosomes and centrioles
Prophase • Centrioles move to opposite sides of the nucleus • Chromosomes start to shorten and thicken • Nuclear membrane begins to breakdown • Spindle fibres form (pathway for chromatids)
Metaphase • Paired chromatids line up at the EQUATOR of the cell • The centromere of each chromosome attaches to its respective spindle fibre • Nuclear membrane no longer apparent
Early Anaphase • Spindle fibres contract (shorten) • Centromere splits between chromatids Mid Anaphase • Chromatids separate and move to opposite poles (centrioles) Late Anaphase • Chromatids arrive at opposite sides of cell
Early Telophase • Nuclear membrane reappears • Chromosomes look less thick and appear as thin threads of chromatin again • Spindle fibres disappear • Nuclear division complete: daughter cell Late Telophase • Cytokinesis occurs and cytoplasm divides • Cell membrane pinches the 2 cells apart at theequator
Cytokinesis • Cell division • The separation of the cytoplasm by a new cell membrane or cell wall to form two new daughter cells
Errors in Mitosis • Mutations • Cause a permanent error, or change, in the normal DNA molecules • Can be caused by various mutagens such as toxic compounds, radiation, or viruses • Mutations are passed on during anaphase and therefore are found in a localized group of cells
FHIT • Found on chromosome 3 • Mutation causes the FHIT gene to undergo mitosis much more rapidly causing the formation of a tumour • Oncogenes • Genes that can be activated by a mutation • Retinoblastoma, Wilms tumour, breast cancer