Mitosis & the Cell Cycle Courtesy of Mill Creek

Cell Growth & Development Are cells of organisms the same size? Do your cells get bigger as you grow, or do you just produce more cells? Are cells of organisms the same size? Do your cells get bigger as you grow, or do you just produce more cells? When talking about Cell Size…… Smaller is Better! When talking about Cell Size…… Smaller is Better! The larger a cell becomes, the more demands the cell places on its DNA, and the harder it is to supply with nutrients. The larger a cell becomes, the more demands the cell places on its DNA, and the harder it is to supply with nutrients.

Cell Division Before a cell becomes to large, a growing cell will divide. Before a cell becomes to large, a growing cell will divide. Cell division is the process by which a Single cell divides into 2 Daughter cells. Cell division is the process by which a Single cell divides into 2 Daughter cells. Cell Division = the series of events that cells go through as they grow and divide. Cell Division = the series of events that cells go through as they grow and divide.

WHAT TO COPY COPY THE NOTES IN YELLOW COPY THE NOTES IN YELLOW

Chromosomes Chromosomes= are composed of DNA- Which carries the cell’s coded genetic information. Chromosomes= are composed of DNA- Which carries the cell’s coded genetic information. Humans have 46 chromosomes(23 pairs). Humans have 46 chromosomes(23 pairs). The chromosomes consist of two identical sister chromatids. The chromosomes consist of two identical sister chromatids.

Two Major Types of Cell Division Mitosis- Somatic cells (Body Cells) Mitosis- Somatic cells (Body Cells) Diploid 2N Diploid 2N Meiosis- Sex cells/ Gametes Meiosis- Sex cells/ Gametes Haploid 1N Haploid 1N

Mitosis Mitosis is the process by which the genetic information is replicated and distributed to daughter cells. Mitosis is the process by which the genetic information is replicated and distributed to daughter cells. 2 diploid(2N) daughter cells are produced from 1 diploid (2N) parent cell. 2 diploid(2N) daughter cells are produced from 1 diploid (2N) parent cell. The Daughter cells are genetically identical to the parent cell. The Daughter cells are genetically identical to the parent cell. There are 4 major stages to mitosis, PMAT. Mitosis does NOT include interphase. There are 4 major stages to mitosis, PMAT. Mitosis does NOT include interphase.

Interphase Interphase= The cell spends most of its life here; not part of the actual reproduction. NOT PART OF MITOSIS. Interphase= The cell spends most of its life here; not part of the actual reproduction. NOT PART OF MITOSIS. Cell grows and replicates its DNA and centrioles. Cell grows and replicates its DNA and centrioles. Nuclear membrane is visible Nuclear membrane is visible Nucleus, Nucleolus, and chromatin can be seen. Nucleus, Nucleolus, and chromatin can be seen.

Interphase

Prophase Prophase: first phase of Mitosis Prophase: first phase of Mitosis Nuclear membrane breaks down Nuclear membrane breaks down Chromosomes become visible Chromosomes become visible Centrioles separate Centrioles separate Spindle forms Spindle forms

Metaphase Metaphase: Second part of Mitosis Metaphase: Second part of Mitosis Chromosomes attach to spindle Chromosomes attach to spindle Chromosomes line up across the center of the cell Chromosomes line up across the center of the cell

Anaphase Anaphase: Third step in Mitosis Anaphase: Third step in Mitosis The sister chromatids separate and move apart The sister chromatids separate and move apart towards opposite poles. towards opposite poles. The chromatids are now called chromosomes.

Telophase Telophase: Fourth stage of Mitosis Telophase: Fourth stage of Mitosis Chromosomes gather at opposite ends of the cell Chromosomes gather at opposite ends of the cell The nuclear membrane begins to form and enclose the chromosomes The nuclear membrane begins to form and enclose the chromosomes Cell membrane begins to move inwards Cell membrane begins to move inwards

Cytokinesis Cytokinesis : Final stage in cellular division Cytokinesis : Final stage in cellular division Not Mitosis Not Mitosis Works with telophase Works with telophase The cytoplasm divides completely in half. The cytoplasm divides completely in half. 2 daughter cells with identical genetic information are produced. 2 daughter cells with identical genetic information are produced.

MEIOSIS Sex cells and gametes

Meiosis is the process by which sex cells/ gametes are produced. Meiosis is the process by which sex cells/ gametes are produced. These sex cells are haploid (1N). These sex cells are haploid (1N).

Human body cells have 46 chromosomes Human body cells have 46 chromosomes Human sex cells, sperm and eggs, have 23 chromosomes. Human sex cells, sperm and eggs, have 23 chromosomes.

Why should gametes have only half the number of normal chromosomes??? During meiosis, FOUR haploid daughter cells are produced from ONE diploid parent cell. During meiosis, FOUR haploid daughter cells are produced from ONE diploid parent cell.

During meiosis the cell actually divides TWICE  Meiosis I and Meiosis II During meiosis the cell actually divides TWICE  Meiosis I and Meiosis II

Meiosis I Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Section 11-4 Figure Meiosis Go to Section:

MEIOSIS I Prophase I: Prophase I: a. Homologous chromosome pairs move together, to form a tetrad. b. Nuclear membrane disappears c. Crossing-over may occur c. Crossing over allows for the exchange of genetic information between neighboring homologous chromosomes

Meiosis I Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Section 11-4 Figure Meiosis Go to Section:

Section 11-4 Crossing-Over Go to Section:

Section 11-4 Crossing-Over Go to Section:

Section 11-4 Crossing-Over Go to Section:

MEIOSIS I Metaphase I: Metaphase I: a. Tetrads line up at the Equator. b. Homologous Chromosomes line up next to each other

Meiosis I Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Section 11-4 Figure Meiosis Go to Section:

MEIOSIS I Anaphase I: Anaphase I: a. ONE homologous chromosome of each pair gets pulled to opposite poles. b. The sister chromatids do not separate. It is still DIPLOID

Meiosis I Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Section 11-4 Figure Meiosis Go to Section:

MEIOSIS I Telophase I and Cytokinesis: Telophase I and Cytokinesis: a. Cells separate; two new cells are formed that are HAPLOID. b. Nuclear membrane REFORMS.

Interphase Interphase occurs between meiosis I and meiosis II to prepare the cell for division again Interphase occurs between meiosis I and meiosis II to prepare the cell for division again NO DNA REPLICATION HAPPENS!! NO DNA REPLICATION HAPPENS!!

Prophase II Chromosomes come together Chromosomes come together Spindle fibers appear Spindle fibers appear

Metaphase II The chromosomes align along middle of the equator. The chromosomes align along middle of the equator.

Anaphase II the fibers pull the chromatids apart and toward opposite ends of the cells. Called disjunction the fibers pull the chromatids apart and toward opposite ends of the cells. Called disjunction

Telophase II The chromatids arrive at the either end of each cell and new nuclear membranes form. The chromatids arrive at the either end of each cell and new nuclear membranes form.

Cytokinesis The rest of the cell continues to divide. Only when two, distinct cells form will cytokinesis, the division of the cell's cytoplasm, be complete. The rest of the cell continues to divide. Only when two, distinct cells form will cytokinesis, the division of the cell's cytoplasm, be complete.

Meiosis II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase IIMetaphase IIAnaphase IITelophase II The chromosomes line up in a similar way to the metaphase stage of mitosis. The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells. Section 11-4 Figure Meiosis II Go to Section:

Meiosis II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase IIMetaphase IIAnaphase IITelophase II The chromosomes line up in a similar way to the metaphase stage of mitosis. The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells. Section 11-4 Figure Meiosis II Go to Section:

Meiosis II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase IIMetaphase IIAnaphase IITelophase II The chromosomes line up in a similar way to the metaphase stage of mitosis. The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells. Section 11-4 Figure Meiosis II Go to Section:

Meiosis II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase IIMetaphase IIAnaphase IITelophase II The chromosomes line up in a similar way to the metaphase stage of mitosis. The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells. Section 11-4 Figure Meiosis II Go to Section:

Meiosis II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase IIMetaphase IIAnaphase IITelophase II The chromosomes line up in a similar way to the metaphase stage of mitosis. The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells. Section 11-4 Figure Meiosis II Go to Section:

Final Results of Meiosis 4 haploid daughter cells which will develop into sex cells 4 haploid daughter cells which will develop into sex cells Each daughter cell has half of the genetic information of a somatic cell Each daughter cell has half of the genetic information of a somatic cell 23 chromosomes for each sex cell 23 chromosomes for each sex cellNOTE: Males will create 4 sperm cells for every one cell that goes through meiosis Females will create 4 egg cells, BUT 3 will turn into non usabale polar bodies and 1 will mature into an egg cell.

Meiosis Animation ations/content/meiosis.html ations/content/meiosis.html