Cell Division

Cell Cycle: Chromosome Binary Fission: Homologous Chromosome: Chromatids Centromere Centriole Mitosis Cytokinesis

Vocabulary Cell Cycle: life cycle of a cell Chromosome: Organized structures of DNA during the cell cycle- Humans have 46 chromosomes Binary Fission: Process of cell division in which 1 cell simply splits into 2 (bacteria) Homologous Chromosome: Chromosomes of matching information (pairs of chromosomes)- Humans have 23 homologous chromosomes Chromatids: Identical copies of chromosomes Centromere: Center that holds the chromatids together Centrioles: Structure that assists in cell division Mitosis: Process of nuclear division (2nd part of cell cycle) Cytokinesis: Process of the cytoplasm dividing (3rd part of cell cycle)

How does the cell know how to divide? Cell Division Reproduction Growth Repair Why do cells divide? How does the cell know how to divide? The DNA has the instructions for all of the cell’s activities.

Cell Division PROKARYOTIC CELLS Bacteria EUKARYOTIC CELLS Binary Fission DNA make copies Cell splits in two EUKARYOTIC CELLS Animal, Plant, Protists, Fungi Cell Cycle Three stage, multistep process to duplicate a cell

Cell cycle Process in which new eukaryotic cells are formed from old cells Life cycle of a cell

Cell cycle Consists of three stages 1. Interphase 2. Mitosis 3. Cytokinesis Results in cells identical to parent cells

Cell Cycle 3 Parts The sequence of development and division of a cell Interphase - Preparation Mitosis – Cell division Cytokinesis – Splitting Adult human cell: ~24 hrs 18-20 hours in interphase 2 hours in mitosis Embryonic cells: 30 min. How long does it take?

1. Interphase Cells grow and copy organelles and chromosomes In-between phase

Interphase What happens Cell doubles in size DNA replicates Organelles double in number

2. Mitosis Process of nuclear division in cells Occurs in eukaryotic cells Four phases (PMAT) Prophase Metaphase Anaphase Telophase

PROPHASE (Pair) Nuclear membrane disappears Chromatids form and pair up Chromosomes are a pair of chromatids held together at the center with a centromere

Mitosis: PROPHASE What happens DNA forms chromosomes Spindle forms Centrioles move toward opposite poles Nuclear membrane begins to disappear

Metaphase (Middle) Chromosomes line up in the middle of the cell

Mitosis: METAPHASE What happens Nucleus has disappeared completely Chromosomes line up in the middle of the cell “equator”

Anaphase (Apart) Chromatids pull apart

Mitosis: ANAPHASE What happens Centromeres divide Chromatids separate and move to opposite poles

Telophase (two) Form two nuclei Nuclear membrane reforms

Mitosis: TELOPHASE What happens Nuclear membrane forms around each group of chromosomes Chromosomes unwind Cytokinesis begins

3. Cytokinesis Cytoplasm divides and forms two new cells In plants… Cell plate forms to split into two Cell plate becomes the new membrane/wall In Animals… Pinch apart to make two cells

Cytokinesis Cytoplasm divides One cell becomes 2 cells What happens

MITOSIS SONG <iframe title="YouTube video player" class="youtube-player" type="text/html" width="480" height="390" src="http://www.youtube.com/embed/1FYFDFDrymQ" frameborder="0" allowFullScreen></iframe>

Mitosis Clips http://www.cellsalive.com/mitosis.htm http://www.youtube.com/watch?v=VGV3fv-uZYI http://www.youtube.com/watch?v=m73i1Zk8EA0 http://www.cellsalive.com/meiosis.htm