Cell+Cycle,+Mitosis+and+Meiosis

= = __**Cell Cycle, Mitosis and Meiosis **__

Cell Cycle and Mitosis
The **cell cycle** is the process for the **reproduction** of cells (excluding the gametes), where one cell splits into two daughter cells. It has three phases: Interphase, **Mitosis** and Cytokinesis. In interphase, the cell makes copies of its organelles and ** replicates its DNA **. In mitosis, chromatin forms **chromosomes**, which come together to form **chromatids**. Chromatid pairs join together, with the **centromere** aiding them in sticking together. Eventually the **envelop of the nucleus** breaks down, the chromatids separate, becoming chromosomes once more and the cell begins to split. It is finally in cytokinesis, where the cell splits to produce its two daughter cells.

Since the **DNA** is copied exactly, the daughter cells are **identica** l to the original. This is an example of asexual reproduction.

Images
Source:[| Halley Hosting Science] || The Process of Mitosis Source: [|Tutor Vista] || Chromatids, Chromosomes, Centromere Source: [|Macro Evolution] ||
 * [[image:http://science.halleyhosting.com/sci/ibbio/cells/notes/ch11/cellcycle3.gif width="332" height="329"]] || [[image:mitosis.gif width="230" height="509"]] || [[image:http://www.macroevolution.net/images/centromere-274-362-10.jpg width="245" height="305"]] ||
 * The Cell Cycle

Meiosis
**Meiosis** is the process where **chromosomes** are divided into half in order to form **sex cells** (sperms and eggs/ovum depending on gender).

Humans have 46 chromosomes in normal cells. Since sex cells combine in reproduction, each sex cell has ** half the number of chromosomes ** (23). Since each cell contributes half the normal number of chromosomes, thus, the offspring of the combination gets the normal number of chromosomes.

Instead of the daughter cells being identical, there is **variation**. This is why, when reproduction occurs, the child never looks exactly like his or her parents.

Images
Source: [|Tutor Vista] || Visual Process of Meiosis (GIF) Source:[| Dr. Chromo's Movies] ||
 * [[image:meiosis_2.gif width="255" height="511"]] || [[image:meiosis.gif]] ||
 * The Process of Meiosis

Cell Cycle and Mitosis:
**Mitosis** is part of the **cell cycle**. It consumes a heavy portion of the cell cycle, but it is only a part, along with interphase and cytokinesis. It is in mitosis, where a cell's **chromosomes** are formed, then combined, then separated again, before splitting into two daughter cells.

Cell Cycle and Meiosis:
Both are ways of **cell reproduction**. ** Meiosis ** specifically refers to the producing of gametes, while the **cell cycle** covers the rest of the cells in the body.

Meiosis and Mitosis:
**Meiosis** and **mitosis** are where one cell begins to reproduce into two cells. Meiosis only covers **sex cells**, while mitosis covers the rest of the cells used for in the body, as it is part of the **cell cycle**.

Purpose and Use
The purpose of the cell cycle and meiosis is **cell division** and **replication**. For the cell cycle, the production of new cells can be used for growth, healing and other life purposes. Meiosis is specifically the process to make sex cells used for **reproduction**.

Similarities

 * Both the cell cycle and meiosis are ways of cell duplication
 * Both follow similar (but not identical steps), (ie. replication, cytokinesis, etc.)

Differences

 * The cell cycle can go on and on, reproducing new cells; meiosis has a start and a finish, starting with one cell and ending with four
 * The cell cycle only produces 2 daughter cells; meiosis produces 4
 * Cell cycle happens in all organisms, including bacteria; meiosis only happens in animals, plants, and fungi
 * Cell cycle occurs in all cells; meiosis occurs only in sex cells
 * The cell cycle's daughter cells are genetically identical; meiosis produces genetically non-identical daughter cells
 * Cell cycle has a constant chromosome number; meiosis reduces the chromosome number by half
 * The cell cycle is asexual reproduction; meiosis functions as sexual reproduction

Other Images
Source: [|Brainpop - Mitosis] || Mitosis Process (GIF) Source: [|Dr. Chromo's Videos - Mitosis] || Source: Prentice Hall: Cells and Heredity, pg. 58-59 || Source: Prentice Hall: Cells and Heredity, pg. 94-95 ||
 * [[image:Screen_shot_2011-12-02_at_11.28.11_AM.png width="310" height="203"]] || [[image:http://www.rothamsted.ac.uk/notebook/images/mitose.gif]] ||
 * Stage of Mitosis
 * [[image:Screen_shot_2011-12-02_at_11.42.11_AM.png]] ||
 * The Cell Cycle
 * [[image:Screen_shot_2011-12-02_at_11.39.32_AM.png width="720" height="271"]] ||
 * Meiosis

Source:[| Youtube] || Meiosis and Mitosis Source: [|Youtube] ||
 * media type="youtube" key="HYKesI9jL8c" width="425" height="350" || media type="youtube" key="-Qf-YelZR-s" width="425" height="350" ||
 * Mitosis Music Video