Mitosis and Meiosis
Mitosis and Meiosis
Purpose
To understand the cell cycle and mitosis and how these two processes function within an organism. To understand meiosis and how this process produces gametes.
Mitosis
All cells in your body complete a cell cycle in which they grow, divide and, eventually, die. The cell cycle consists of four phases: G1, S, G2, and M (Figure 1). Each phase is associated with a specific cellular function: typically growth, synthesis, and division. The G1, S, and G2 phases comprise a larger phase called interphase. During interphase, the cell grows and synthesizes (replicates) DNA in preparation for division. The G1 phase, also called Gap 1, is the first phase of interphase. During G1, the cell increases in size. The S phase, also called the synthesis phase, follows G1. During S phase, the cell synthesizes DNA. Each chromosome is now comprised of two identical sister chromatids as a result of DNA synthesis. The G2 phase, also called Gap 2, follows the S phase. During G2, the cell once again increases in size and produces proteins necessary for Mitosis. After G2, the cell is ready to begin the next phase in its life cycle, the mitotic phase.
Figure 1. The cell cycle.
Mitosis is a type of cell division process used by somatic cells. Somatic cells are all cell types excluding the germ cells, which produce gametes. Skin cells, liver cells, and brain cells are examples of somatic cells. Every cell in the human body, with the exception of gametes, contains 46 chromosomes. The number of chromosomes contained in each cell is called the diploid (2n) number. In humans, the diploid number is 46. Other organisms have different diploid numbers. For example, dogs have a diploid number of 78, guinea pigs have a diploid number of 64, and apples have a diploid number of 34. A somatic cell is always diploid, even after it divides.
Mitosis: 2n → 2n
Mitosis is divided into four phases: prophase, metaphase, anaphase, and telophase/ cytokinesis
Purpose
To understand the cell cycle and mitosis and how these two processes function within an organism. To understand meiosis and how this process produces gametes.
Mitosis
All cells in your body complete a cell cycle in which they grow, divide and, eventually, die. The cell cycle consists of four phases: G1, S, G2, and M (Figure 1). Each phase is associated with a specific cellular function: typically growth, synthesis, and division. The G1, S, and G2 phases comprise a larger phase called interphase. During interphase, the cell grows and synthesizes (replicates) DNA in preparation for division. The G1 phase, also called Gap 1, is the first phase of interphase. During G1, the cell increases in size. The S phase, also called the synthesis phase, follows G1. During S phase, the cell synthesizes DNA. Each chromosome is now comprised of two identical sister chromatids as a result of DNA synthesis. The G2 phase, also called Gap 2, follows the S phase. During G2, the cell once again increases in size and produces proteins necessary for Mitosis. After G2, the cell is ready to begin the next phase in its life cycle, the mitotic phase.
Figure 1. The cell cycle.
Mitosis is a type of cell division process used by somatic cells. Somatic cells are all cell types excluding the germ cells, which produce gametes. Skin cells, liver cells, and brain cells are examples of somatic cells. Every cell in the human body, with the exception of gametes, contains 46 chromosomes. The number of chromosomes contained in each cell is called the diploid (2n) number. In humans, the diploid number is 46. Other organisms have different diploid numbers. For example, dogs have a diploid number of 78, guinea pigs have a diploid number of 64, and apples have a diploid number of 34. A somatic cell is always diploid, even after it divides.
Mitosis: 2n → 2n
Mitosis is divided into four phases: prophase, metaphase, anaphase, and telophase/ cytokinesis