Cell Division Mitosis
Overview of Mitosis 1 Cell (mother cell) divides into 2 Cells (daughter cells) Each new cell is an exact copy of the mother cell
Importance of Mitosis Growth – adding new cells Replacement – replacing dead cells Repair – Replacing cells that are damaged or injured
Structures - Nucleus The Nucleus is the control center of the cell Chromatin is the threadlike structures in the nucleus Chromatin is made of DNA and a few other things
Structures – Nuclear Membrane The Nuclear Membrane separates the nucleus from the rest of the cell The Nuclear Membrane disappears during cell division
Structures - Chromosomes Chromosomes are visible when a cell is dividing All species of plants and animals have a certain number of chromosomes in their body cells
Structures - Chromosomes Chromosomes are made of two chromatids connected by a centromere
Structures - Genes Genes are structures or locations on the chromosomes that carry information for the cell’s activity Genes carry coded instructions that are similar to an architect’s blueprint
Structures - DNA DNA is the chemical that makes up genes and chromosomes
Structures - Centrioles Centrioles are organelles outside the nucleus that anchor the spindle fibers
Structures – Spindle Fibers Spindle fibers form when a cell is dividing They pull chromosomes to opposite ends of the mother cell
Chromosome Numbers Examples Man – 46 (23 pair) Chromosomes Midge – 4 (2 pair) Crayfish – 208 Fern – 768 Pea – 14 Corn – 20 Monkey – 42 Rabbit – 44 Mouse – 4 Moth – 62 Potato – 48 Tomato – 24 Sunflower-34 Frog-26 Cow-60 Horse-64 All members of an animal or plant species have the same number of chromosomes
The Cell Cycle Prophase Anaphase Telophase Metaphase Interphase The cellscycle includes a resting phase, the 4 phases of mitosis, and cell separation. Interphase Prophase Metaphase Anaphase Telophase Cytokinesis
Mitosis - Interphase Interphase is a resting phase - a period of growth and development where the chromosomes are not visible. Duplication of the chromosomes takes place (exact copies are made)
Mitosis - Prophase In Prophase, the chromosomes become visible under a microscope They become short, thick, and paired up The nuclear membrane begins to disappear
Mitosis - Metaphase Nuclear Membrane completely gone Pairs of Chromosomes line up in the middle of the cell Spindle fibers attach to the chromosome pairs
Mitosis - Anaphase The chromosomes are pulled apart and the chromatids are pulled and move to the opposite ends of the cell
Mitosis - Telophase Spindle fibers disappear Chromosomes begin to stretch out and lose their rodlike appearance. A new nuclear membrane forms around each region of chromosomes.
Cytokinesis Cell membrane pinches in around the middle of the cell. The result is a new daughter cell that is identical to the parent cell. It should have the same number of identical chromosomes.