BLG 400 Lecture Notes - Lecture 6: Sister Chromatids, Gene Duplication, Germ Cell
Document Summary
The cell cycle is a repeating pattern of cell growth and division: Most cell growth occurs in g1 and g2. Some terminally differentiated cells stop dividing and arrest in g0. Chromosomes replicate to form sister chromatids in s. Chromosome dynamics during g1, s and g2 phase of cell cycle. Prophase: chromosomes condense and become visible, centrosomes move apart toward opposite poles. Prometaphase: nuclear envelope breaks down, microtubules from centrosomes invade the nucleus and connect to kinetochores in centromere of each chromatid, sister chromatids attach to microtubules from opposite poles. Metaphase: chromosomes align on the metaphase plate with sister chromatids facing opposite poles, forces pushing and pulling chromosomes to or from each pole are in balanced equilibrium. Anaphase: centromeres of all chromosomes divide simultaneously, kinetochore microtubules shorten and pull separated sister chromatids to opposite poles (characteristic v shape) Telophase: rewind of prophase, nuclear envelope forms around each group of chromatids, spindle fibres disperse, chromosomes decondense.