Mitosis

What is Mitosis? The division of a cell into 2 identical daughter cells.

Advantages of Mitosis Guarantees genetic continuity. Results in the production of 2 new cells with chromosome sets that are identical to those of the parent cell.

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The Cell Cycle: 5 steps: Interphase Prophase Metaphase Anaphase Telophase Mitosis

Before mitosis… Interphase: a growth period G1- Cell grows in size, makes new organelles, performs assigned function S phase-duplicates DNA to prepare for mitosis G2-short functional phase and prepares for mitosis.

Mitosis occurs in 4 phases Prophase Metaphase Anaphase Telophase

Prophase DNA is organized Nuclear membrane & nucleolus disappear. long stringy chromatin coils up into visible chromosomes. Chromosomes are paired with their identical copies and are called sister chromatids. Sister chromatids are held together as a pair by a centromere. Nuclear membrane & nucleolus disappear. Spindle fibers forms between the pairs of centrioles, which have moved to opposite ends of the cell Prophase

Vocab Terms Chromosomecell structure that carries the genetic material Sister chromatidsidentical halves of the duplicated parent chromosome Centromerecell structure that joins two sister chromatids of a chromosome Centriolespair of cylindrical structures that move to opposite ends of the cell during prophase. Spindlethin fiber structure that forms between the 2 centrioles

Metaphase Chromosomes line up in the middle of the cell. Each chromatid is attached to a separate spindle fiber by its centromere. Metaphase

Anaphase The centromeres split and the sister chromatids are pulled apart to opposite poles of the cell.

Telophase 2 daughter cells are formed. Cytokinesis occurs (the division of the cytoplasm) as the plasma membrane pinches in along the equator. Nucleolus and nuclear membrane reappear, chromosomes begin to uncoil.

Picture of cytokinesis *Image courtesy Indigo Instruments. Visit indigo.com for more original content like this. Reprint permission is granted with this footer included.*

In plants… Because plant cells have a cell wall, the plasma membrane does not pinch in. Rather a structure known as the cell plate forms across the cell’s equator.

Plant in cytokinesis It’s hard to see, but there is a cell plate forming in the middle of the cell, next to the arrow.

Finally… After mitosis is complete, each new daughter cell then enters interphase until they are ready to divide.

All together now…