How Cells Divide

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html

Interphase What the cell spends 90% of its time doing. Divided into G1,S, and G2 stages This is where the cell goes about basic life functions of growth, DNA copying and regulation

G1 During this stage new organelles are being synthesised, so the cell requires both structural proteins and enzymes, resulting in great amount of protein synthesis. In short the cell grows (Growth phase) http://en.wikipedia.org/wiki/G2_phase

S synthesis phase, is a period when DNA synthesis or replication occurs.

G2 Cell grows more and prepares to divide

Cell cycle

Did you notice the check points?

Mitosis (The M phase) Before We Split mitosis= the division of a cell's nucleus. Along with cytokinesis (the division of the rest of a cell), mitosis results in a parent cell dividing into two daughter cells. The genetic information within each of these daughter cells is identical.

This is how we get sister chromatids http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html This is how we get sister chromatids

Nuclear envelope breaks down Spindle fibers (microtubules) attach http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html Nuclear envelope breaks down Spindle fibers (microtubules) attach Sister chromatids pair up Spindle fibers form

Chromosomes line up in the center of the cell http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html Chromosomes line up in the center of the cell ½ of each chromosome (1 chromatid) is pulled to each pole of the cell

Nuclear envelope reforms http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html Nuclear envelope reforms

Cytokinesis (the final step) Cytokinesis is the process of splitting the daughter cells apart. Whereas mitosis is the division of the nucleus, cytokinesis is the splitting of the cytoplasm and allocation of the golgi, plastids and cytoplasm into each new cell. http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html

Meiosis

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html

Prophase I http://www.biology.arizona.edu/CELL_BIO/tutorials/meiosis/page3.html Homologous chromosomes pair up (each made up of 2 sister chromatids) Homologous chromosomes swap some allele information Nuclear envelope disappears

See information is swapped Metaphase I See information is swapped http://www.biology.arizona.edu/CELL_BIO/tutorials/meiosis/page3.html Chromosomes line up down the middle Spindle fibers attach

Anaphase I http://www.biology.arizona.edu/CELL_BIO/tutorials/meiosis/page3.html 1 of each of the Homologous chromosomes is pulled to each side of the cell

Telophase I & Cytokinesis http://www.biology.arizona.edu/CELL_BIO/tutorials/meiosis/page3.html The cell divides down the middle Nuclear envelope sometimes reforms

Telophase I & Cytokinesis http://www.biology.arizona.edu/CELL_BIO/tutorials/meiosis/page3.html The cell divides down the middle Nuclear envelope sometimes reforms

No new Interphase!

Prophase II Spindle fibers form Nuclear envelope disintegrates

Metaphase II Chromosomes line up in the center of the cell Spindle fibers attach

Anaphase II Sister chromatids separate http://taggart.glg.msu.edu/bs110/meiosis.htm

Telophase II & Cytokinesis Nucleus reforms Not that each of the four cells is haploid http://taggart.glg.msu.edu/bs110/meiosis.htm

Did catch the Differences? Check out this Sweet animation

Taken from http://biologyinmotion.com/cell_division/index.html

Comparing the Two

So.... Homologous chromosomes swap information in meiosis In meiosis 1 homologous chromosomes not sister chromatids are separated Meiosis ends with 4 daughter cells, Mitosis ends in 2

http://www.accessexcellence.org/RC/VL/GG/comparison.html