Mitosis

•Your body makes millions of new cells every few seconds! •Your body makes new cells to reproduce, and to grow and replace cells that have died.

Asexual cell reproduction

Mitosis

•Only one parent cell needed •Structures inside cell are copied and parent cell divides, making two exact copies •Most cells in your body (ex. skin cell) and most single-celled organisms reproduce this way

•DNA (the genetic material in all cells) must duplicate before a cell divides in both prokaryotic and eukaryotic cells. •During most of a cell's life cycle; DNA is wrapped around proteins to form a complex material called chromatin (also called chromatids)

Chromatin

•Have no nucleus and have a single, circular DNA molecule. • Binary fission - cell division in bacteria where the bacterium literally splits into two parts; each part contains a copy of the circular DNA

Binary fission

•More complex than bacteria and contains more DNA. •Early in cell division, chromatin is compacted into visible structures called chromosomes. • Chromosomes - the visible duplicated DNA found in the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells. •A duplicated chromosome consists of two identical structures called chromatids. -Chromatids are held together by a structure called the centromere. •Chromatids are the strands of DNA (also called chromatin) that are wound around proteins so that the large amount of DNA can fit inside a cell.

chromosomes

Chromosomes

chromatids/chromatin

centromere.

chromatids/chromatin

•The total length of DNA present in one human would measure at 2.0 × 1013meters in length when laid end-to end. That is the equivalent of nearly 70 trips from the earth to the sun and back! •There is nearly 6ft of DNA in every one of your 100 trillions of cells. •Fruit flies have 8 chromosomes, potatoes have 48, and humans have 46 (being more complex doesn't equal more chromosomes)

The Life of A Cell: •Every cell passes through different stages in their life; we call this the cell cycle. •The cell cycle begins when cells are formed and end when the cell divides and forms new cells. •Before cellular division, DNA must be copied to ensure that each new cell (daughter cell) will be an exact copy of its parent cell. •The rate of mitosis in most animals is about 25 million cells/second

cells are formed

cells divide and form new cells

must be copied to ensure each new cell (daughter cell) will be an exact copy of its parent cell.

25 million cells/second

•A cell at any given time is in one of the following 3 stages of the cell cycle: 1.Interphase - cell grows and copies its organelles and chromosomes; the two copies are now called chromatids. 2. Mitosis: chromatid separation. 4 stage process in Eukaryotic cells where cell division forms two new nuclei, each with the same number of chromosomes •Mitosis ensures that each new cell receives a copy of each chromosome 3.Cytokinesis - cell division •Once mitosis is complete, the cell splits into two identical cells •In eukaryotic cells with no cell wall, division of the cytoplasm begins at the cell membrane and then begins to pinch inward to form a groove •In plants, algae, and fungi, a cell plate forms in the middle of the cell and becomes the new cell membranes that separate the new cells

Interphase stage

Mitosis

Cytokinesis - cell division

at the cell membrane and then begins to pinch inward to form a groove

In plants, algae, and fungi,

1.Prophase - beginning of mitosis •nuclear membrane dissolve •chromosomes condense into rodlike structures 2.Metaphase - •chromosomes line up along the equator of the cell •homologous chromosomes pair up 3.Anaphase - •chromatids separate and move to opposite sides of the cell 4.Telophase - stage where mitosis is complete •nuclear membrane forms around each set of chromosomes •chromosomes unwind

prophase

metaphase

anaphase

telophase