Introduction to Mitosis

All cells need to reproduce so that new cells can be created. The information in each new cell must be EXACTLY the same as the cell before.

The process that creates new cells from old cells is called mitosis.

The Cell Cycle - represents the events during the life span of a cell - consists of: Interphase, Mitosis and Cytokinesis

Interphase: is a period of nondivision. It consists of: cell growth DNA synthesis (single stranded chromosomes become double stranded)

Mitosis : is a period of active division of both nuclear and cellular contents. Mitosis is controlled by the nucleus. The nucleus is the brain of the cell

Terminology

DNA is the chemical molecule that makes up the cell’s genetic material. Genes are sets of instructions that make up portions of your DNA.

Chromosomes – are double-stranded structures located in the nucleus that are made up of tightly coiled DNA.

Chromatin – fine, threadlike chromosomes in a state of resting during interphase.

Chromatids – when chromosomes replicate, the two strands are called sister chromatids. They are connected by a centromere.

MITOSIS: Sister chromatids separate and the cell divides into two daughter cells Each daughter cell contains the same number of chromosomes as the parent and an equal amount of cytoplasm and organelles

PMAT Prophase Metaphase Anaphase Telophase There are 4 main phases: A PROfessional hockey player MET a girl named ANA and they used to communicate by the TELOphone but now use the INTERnet.

1. PROPHASE: Chromosomes are thick and DNA has replicated Nuclear membrane dissolves Centrioles move to opposite poles (ends) of the cell Spindle fibers form and stretch across the cell

2. MetaPHASE: Spindle fibers attach to centromeres Chromosomes line up along the equator of the cell

3. anaPHASE: Spindle fibers shorten, pulling the centromere apart so that one sister chromatid moves to each pole of the cell

4. teloPHASE: One complete set of chromosomes is at the end of each pole of the cell. Spindle fibers disappear A nuclear membrane forms around each set of chromosomes A nucleolus appears within each nucleus Single-stranded chromosomes start to uncoil into thin strands of chromatin Now there are two nuclei in one cell and the cell is ready to divide. Mitosis ends

Cytokinesis After mitosis is complete the cell must must completely divide. In animal cells, the cell membrane pinches off in a process called cytokinesis In plant cells, a cell plate grows in the middle of the cell forming a new cell wall