Unit 3: Genetics I: Cellular reproduction describes and explains how genetic inheritance occurs asexually through mitosis and sexually through meiosis

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Lecture Notes

6.3 Mitosis and Cytokinesis

A. In mitosis, chromatids are pulled by microtubules, which are proteins making up the spindle

• during G2, centrioles are repicated and spindle fibers made of hollow tubes of protein are assembled in preparation for mitosis
• during mitosis microtubule spindle fibers attach to the centromeres of chromosomes
• ends of microtubules are broken down, moving chromatids towards opposite poles

B. Mitosis is the duplication of the nucleus

• prophase is the longest phase of mitosis

     1. chromosomes coil up and become visible
     2. nucleolus disappears 
     3. nuclear membrane dissolves
     4. spindle appratus forms 
     5. centrioles move to opposite poles

• metaphase: chromosomes line up along equator

• anaphase:

     1. centromeres divide
     2. chromatids (now called chromosomes) move toward opposite poles

• telophase

     1. chromosomes uncoil
     2. two nuclear membranes reform, one at each pole 
     3. spindle dissolves

D. Cytokinesis divides cells, producing two genetically identical daughter cells

• animal cells: cell membrane pinches inward by a belt of proteins
• plant cells: new cell wall produced between two daughter cells from Golgi apparatus vessicles producing a cell plate