Download Chapter 12 The Cell Cycle

Chapter 12 The Cell Cycle
Cell Division - the reproduction of cells
Cell cycle - the life of a cell from its origin in the division of parent cell until its own
division into two
Functions of Cell Division
Reproduction
Growth and development
Tissue renewal
DNA in the Cell
Genome - a cell’s total hereditary endowment of DNA
Chromosomes – how DNA is packaged in the nucleus
Chromatin – the DNA-protein complex
Types of Cells
Somatic cells - all body cells except the reproductive cells
Gametes – reproductive cells, sperm and egg cells
Humans – 46 and 23 chromosomes, respectively
Chromosomes (Fig 12.3)
Sister chromatids - two identical copies of the chromosome’s DNA molecule duplicated
in preparation for cell division
Centromere - Specialized region of the chromosome seen as a narrow “waist” when the
chromosome is condensed
Cell Division Terms (Animation)
Mitosis - division of the nucleus
Cytokinesis – division of the cytoplasm
The cell cycle (Fig 12.4)
M phase - cell cycle phase that includes both mitosis and cytokinesis
Interphase - cell cycle phase other than M phase, accounts for about 90% of the cell cycle
G1 phase - First growth phase
S phase – DNA synthesized to duplicate the chromosomes
G2 phase – Second growth phase
Subphases of Mitosis (Animations, Fig 12.5 & 12.9)
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Mitotic spindle - a structure composed of microtubules which is necessary for mitosis (Fig 12.6)
Kinetichore - a structure of proteins and specific sections of chromosomal DNA at the
centromere
Metaphase plate - a plane midway between the two spindle poles
Cytokinesis (Fig 12.8)
Cleavage furrow - a shallow groove in the cell surface near the old metaphase plate
Cell plate - vesicle derived divider between two dividing plant cells
Prokaryotic Cell Division
Binary fission - division in half by bacteria (Fig 12.10)
Cell Cycle Regulation (Fig 12.13 & Fig 12.14)
Cell-cycle control system - a cyclically operating set of molecules that both triggers and
coordinates key events in the cell cycle
Checkpoints - a critical control point where stop and go-ahead signals can regulate the
cycle
Cyclins - proteins that get their names from their cyclically fluctuating concentration in
the cell
Cyclins-dependent kinases (Cdk) - enzymes that drive the cell cycle, they must be paired
with a cyclin to be active
MPF (M-phase promoting factor) - a Cdk-cyclin pair
Cancer
Transformation - the process that converts a normal cell to a cancer cell
Tumor - a mass of abnormal cells within an otherwise normal tissue
Benign tumor - tumor that remains at the original site
Malignant tumor - an invasive tumor that will impair the function of one or more
organs
Metastasis - the spread of cancer cells beyond their original site (Fig 12.17)