1. Cell division How one cell becomes two

2. Mitosis + Cytokinesis = Cell division Most cells in all eukaryotic organisms will divide many times throughout the life of the organism –_______________ is the process by which a cell duplicates its genetic materials (chromosomes and prepares for cell division –________________ is the division of the rest of the cell into two separate but identical daughter cells –__________________________________________ __________________________________________ __________________________________________ In animals, cell division occurs during embryonic development, growth, and wound healing Errors during cell division can cause cell death or cancer

3. Mitosis reorganizes DNA in the cell ______________________________________ ______________________________________ ______________________________________ During mitosis, the two copies are reorganized, repackaged into two sets of chromosomes, and divided to opposite ends of the cell In most organisms, ______________________________________ ______________________________________ ______________________________________ _(the cell body dividing in two) The original cell (mother cell) is identical to the two resulting cells (daughter cells)

4. Mitosis vocabulary Nucleus – location of DNA inside the cell Nuclear envelope – the membrane that separates the nucleus from the cytoplasm DNA – an incredibly long molecule that contains genetic blue prints for cell behavior Chromatin – a loosely bundled coil of DNA. Most of the time, DNA is organized in this form, “ a loose rope” Histones – proteins which hold a DNA strand together in the form of chromatin Chromosome – a highly organized form of chromatin, “a tightly wrapped and carefully knotted rope ” –Each chromosome is composed of two identical parts called chromatids –Chromatids: two halves of a chromosome which contain the same genetic information –DNA exists in the form of chromosomes only during mitosis –Each chromosome looks like an X Centromere – a bundle of proteins which connects the two chromatids of a chromosome, the “knot at the center of the X“ Microtubules – part of a cell’s cytoskeleton. These are tubes of protein which use to pull chromosomes apart and to opposite ends of a cell during mitosis. They are powered by ATP! Mitotic spindle – How microtubules are organized during mitosis. This is a collection of microtubule fibers which is formed to coordinate the pulling of apart of chromosomes. Metaphase plate – the line along which chromosomes are lined up during mitosis. This arrangement is coordinated by the mitotic spindle.

5. Chromosome Structure

6. 5 Phases of Mitosis Mitosis is composed of five phases –___________________ During each phase, different proteins in the cell perform specific roles to divide the two copies of genetic material _________________________________________ _________________________________________ _________________________________________

8. Prophase ________________________ ________________________ ________________________ into chromosomes inside the nucleus Microtubules are organized into _____________________ in the cytoplasm Nuclear envelope is dissolving By the end of prophase –Chromosomes and mitotic spindle are fully organized –Nuclear envelope has disappeared

9. Prometaphase Chromosomes move towards each other and into the center of the cell Microtubules move into the nuclear region and begin to connect to chromosomes ____________________ ____________________

10. Metaphase The mitotic spindle is fully organized, and has pulling the chromosomes to the center of the cell The spindle aligns chromosomes so that each centromere is lined up along the metaphase plate (the center of the cell)

11. Anaphase _______________________ _______________________ Microtubule fibers contract (___________________), pulling chromatids to opposite ends of the cell towards the two spindles

12. Telophase _________________________ _________________________ New nuclear envelopes begin to form around the chromatin to create two nuclei Spindle fibers disperse into the cytoplasm The cell membrane begins to cleave in preparation for cytokinesis

13. Cytokinesis The cell membrane is being pinched off to form two separate compartments Cytoplasm and organelles are being divided between the two forming cells __________________________________ __________________________________ Cell division is complete!

14. Cell division movies http://www.youtube.com/watch?v=VlN7K1- 9QB0http://www.youtube.com/watch?v=VlN7K1- 9QB0 http://www.youtube.com/watch?v=CzPGh YiGyZ8&feature=relatedhttp://www.youtube.com/watch?v=CzPGh YiGyZ8&feature=related Embryonic division in the worm c.elegans: http://www.youtube.com/watch?v=zsgOl04 PESI&NR=1 http://www.youtube.com/watch?v=zsgOl04 PESI&NR=1 http://www.cellsalive.com/mitosis.htm