The Cell Cycle & Cell Division

The Cell Cycle http://www.nobel.se/medicine/laureates/2001/press.html

Animated Cycle http://www.cellsalive.com/cell_cycle.htm

MITOSIS

Mitosis The process of cell division which results in the production of two daughter cells from a single parent cell. The daughter cells are identical to one another and to the original parent cell.

Mitosis can be divided into stages Interphase Prophase Metaphase Anaphase Telophase & Cytokinesis

Interphase The cell prepares for division Animal Cell DNA replicated Organelles replicated Cell increases in size Plant Cell DNA replicated Organelles replicated Cell increases in size

Interphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Prophase The cell prepares for nuclear division Animal Cell Packages DNA into chromosomes Plant cell Packages DNA into chromosomes

Prophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Metaphase The cell prepares chromosomes for division Animal Cell Chromosomes line up at the center of the cell Spindle fibers attach from daughter cells to chromosomes at the centromere Plant Cell Chromosomes line up at the center of the cell Spindle fibers attach from daughter cells to chromosomes at the centromere

Metaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Anaphase The chromosomes divide Animal Cell Spindle fibers pull chromosomes apart ½ of each chromosome (called chromotid) moves to each daughter cell Plant Cell Spindle fibers pull chromosomes apart ½ of each chromosome (called chromotid) moves to each daughter cell

Anaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Telophase The cytoplasm divides Plant Cell DNA spreads out 2 nuclei form New cell wall forms between to nuclei to form the 2 new daughter cells Animal Cell DNA spreads out 2 nuclei form Cell membrane pinches in to form the 2 new daughter cells

Telophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

II. The “C” Words in Mitosis A. Chromatin 1. DNA + protein - found in nucleus of a non-dividing cell B. Chromatid 1. one of two identical parts of a chromosome in a mitotic cell 2. sister chromatids are identical a. same DNA and the same genes

1. holds sister chromatids together C. Centromere 1. holds sister chromatids together 2. attaches chromosome to spindle fibers D. Centrosomes 1. found in plant and animal cells 2. spindle fibers radiate from a pair of these during mitosis E. Centrioles 1. found in the centrosomes of animal cells only 2. one pair in each centrosome

REVIEW THE CELL CYCLE A. Interphase 1.G1- cells grow & mature(time between) between division and DNA replication) 2.G0 - DNA does not replicate (cell will not divide) S – DNA replicates 3.G2 – cell prepares for division if the DNA does replicate (cell will divide)

Cell Cycle

The Cell Cycle B. Mitosis 1. Prophase a. chromosomes become visible b. centrosomes appear, separate and move toward poles c. spindle appears d. nucleolus and nuclear membrane disappear

Interphase Prophase

2. Metaphase a. chromosomes line up at equator 3. Anaphase a. centromeres divide b. sister chromatids separate 1) considered individual chromosomes c. chromosomes begin to move apart d. chromosomes move to opposite poles

Metaphase Late Anaphase

4. Telophase a. chromosomes reach the poles b. spindles disappear c. nuclear membrane and nucleolus reappear in each cell d. chromosomes become less distinct e. cytokinesis begins

Metaphase Interphase Telophase-Cytokinesis

C. Cytokinesis 1. a cleavage furrow develops in animal cells - a cell plate forms in plant cells 2. two distinct daughter cells form 3. daughter cells enter interphase 4. offspring cells have identical copies of chromosomes and ½ the original cell cytoplasm and organelles

Mitosis Animation http://www.cellsalive.com/mitosis.htm

mitosis Events during Mitosis Interphase: Cells may appear inactive during this stage, but they are quite the opposite. This is the longest period of the complete cell cycle during which DNA replicates, the centrioles divide, and proteins are actively produced. For a complete description of the events during Interphase, read about the Cell Cycle. Prophase: During this first mitotic stage, the nucleolus fades and chromatin (replicated DNA and associated proteins) condenses into chromosomes. Each replicated chromosome comprises two chromatids, both with the same genetic information. Microtubules of the cytoskeleton, responsible for cell shape, motility and attachment to other cells during interphase, disassemble. And the building blocks of these microtubules are used to grow the mitotic spindle from the region of the centrosomes. Prometaphase: In this stage the nuclear envelope breaks down so there is no longer a recognizable nucleus. Some mitotic spindle fibers elongate from the centrosomes and attach to kinetochores, protein bundles at the centromere region on the chromosomes where sister chromatids are joined. Other spindle fibers elongate but instead of attaching to chromosomes, overlap each other at the cell center. mitosis

mitosis MITOSIS Metaphase: Tension applied by the spindle fibers aligns all chromosomes in one plane at the center of the cell. Anaphase: Spindle fibers shorten, the kinetochores separate, and the chromatids (daughter chromosomes) are pulled apart and begin moving to the cell poles. Telophase: The daughter chromosomes arrive at the poles and the spindle fibers that have pulled them apart disappear. Cytokinesis: The spindle fibers not attached to chromosomes begin breaking down until only that portion of overlap is left. It is in this region that a contractile ring cleaves the cell into two daughter cells. Microtubules then reorganize into a new cytoskeleton for the return to interphase. Cancer cells reproduce relatively quickly in culture. In the Cancer Cell CAM compare the length of time these cells spend in interphase to that for mitosis to occur.

Animal Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

Plant Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase