文档介绍：D103 lecture 23 ? 2011 Grant MacGregor & Christine S ü tterlin – All rights reserved Page 1 Lecture 23 – Mitosis mended Reading: MBOC 5e, pages 710 – 712; 1071 - 1090 Metaphase Anaphase D103 lecture 23 ? 2011 Grant MacGregor & Christine S ü tterlin – All rights reserved Page 2 Mitosis - what must the cell plish ? Essentially no new protein synthesis after entry into mitosis – Need to retain proteins required for survival immediately after cytokinesis ! Condense chromosomal DNA before trying to separate sister chromatids - Think it would be easy to quickly separate many overlapping balls of unwound string ? Disassemble nuclear envelope - Can you connect chromosomes to the centrosomes while the nuclear envelope is in between them ? Ensure sister chromatids are reliably and quickly sorted one per daughter cell - How to make a dynamic scaffold that allows us to assemble and move correct number of chromosomes ? Disassemble the scaffold, reform the nuclear envelope, allow chromatin to anize - How to plish this without significant new protein synthesis ? or D103 lecture 23 ? 2011 Grant MacGregor & Christine S ü tterlin – All rights reserved Page 3 Mitosis - rush hour in the cell cycle What events take place during Mitosis ? ? Centrosomes separate and chromosomes condense (prophase). ? Scaffolding forms to align and help separatechromosomes . ? Nuclear envelope removed and chromosome capture occurs ( prometaphase) - note; yeast and slime-mold use “ closed ” mitosis, where there is no breakdown of the nuclear envelope. ? Chromosomes are aligned on spindleequator (metaphase). ? Sister chromatids move to opposite poles of cell (anaphase A). ? Cell elongates via spindle elongation (anaphase B). ? Cleavage furrow forms , nuclear envelope reforms ( telophase). D103 lecture 23 ? 2011 Grant MacGregor & Christine S ü tterlin – All rights reserved Page 4 The centrosome duplicates during interphase ? At