Chapters 10 and 11: Cell Growth and Division Mitosis/Meiosis/Cancer

Why is it necessary for cells to divide? DNA Overload-not enough information for the cell as it grows larger in size To improve material exchange Volume of cell increases faster than surface area

What is Cell Division ? process where a cell divides into two new daughter cells Before cell division takes place, the cell must copy or replicate its DNA. Each daughter cells gets a complete copy of the original DNA Cell division has 2 parts Mitosis: division of nucleus and DNA Cytokinesis: division of cytoplasm and organelles

Chromosomes- condensed form of DNA Sister chromatids- 1 chromosome and a copy of it “tied” together before the cell divides Centromere- the chemical “knot” holding sister chromatids together LABEL THE DIAGRAM IN YOUR NOTES.

Figure 10–4 The Cell Cycle

Figure 10–4 The Cell Cycle G1 phase M phase S phase G2 phase

Figure 10–5 Mitosis and Cytokinesis Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Prophase-Phase #1 of Mitosis Longest Phase-50% to 60% of total time to complete mitosis Chromatin condenses into Chromosomes Centromeres connect sister chromatids Centrioles separate to opposite poles Spindle is organized Nucleolus disappears and nuclear envelope breaks down.

Figure 10–5 Mitosis and Cytokinesis Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Metaphase-Phase #2 of Mitosis Centromeres attach to spindle fibers Chromosomes line up across the equator of the cell-metaphase plate

Figure 10–5 Mitosis and Cytokinesis Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Anaphase-Phase #3 of Mitosis Sister chromatids separate becoming individual chromosomes and moving to opposite poles of cell

Figure 10–5 Mitosis and Cytokinesis Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Telophase-Phase #4 of Mitosis Chromosomes disperse into chromatin Nuclear envelope re-forms around each cluster of chromatin Spindle breaks apart Nucleolus visible in each new daughter cell

Figure 10–5 Mitosis and Cytokinesis Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Cytokinesis Division of cytoplasm and organelles Animal Cells: Cleavage Furrow-cell membrane pinches inward Plant Cells: Cell Plate-develops into separating membrane (cell wall appears shortly after)

Figure 10–5 Mitosis and Cytokinesis Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Cytokinesis

Prophase Interphase

Metaphase Prophase

Anaphase

Telophase

Cancer Disorder in which some cells lose ability to control growth Form tumors Carcinogen- cancer causing agent (ex. Cigarettes, UV radiation from sun)

Regulating the Cell Cycle

Asymmetrical, Borders, Color, Diameter, Elevation Skin Cancer : Melanoma Asymmetrical, Borders, Color, Diameter, Elevation

Meiosis Cell Division to produce gametes-sex cells (sperm and egg) Number of chromosomes per cell is cut in half through separation of homologous chromosomes in diploid cell

Homologous Chromosomes Chromosomes containing same genes 1 chromosome from mom and 1 chromosome from dad Diploid=2N-cell that has both copies meaning 2 complete sets of genes/chromosomes (all regular cells-somatic cells) In humans 2n=46 Haploid=N-cell that has one set/copy (gametes/sex cells) In humans n=23

Crossing over occurs during Prophase I, and homologous chromosomes exchange portions of their chromatids (DNA)

Figure 11-15 Meiosis Section 11-4 Meiosis I

Figure 11-15 Meiosis Section 11-4 Meiosis I Meiosis I

Figure 11-15 Meiosis Section 11-4 Meiosis I Meiosis I

Figure 11-15 Meiosis Section 11-4 Meiosis I

Figure 11-15 Meiosis Section 11-4 Meiosis I

Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II Metaphase II Anaphase II Telophase II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. 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.

Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II Metaphase II Anaphase II Telophase II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. 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.

Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II Metaphase II Anaphase II Telophase II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. 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.

Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II Metaphase II Anaphase II Telophase II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. 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.

Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II Metaphase II Anaphase II Telophase II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. 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.

Gamete Formation In males4 sperm cells are produced In females1 egg cell is produced Other 3 cells=polar bodies-not involved in reproduction and eventually degenerate b/c do not receive enough cytoplasm containing nutrients

Mitosis Meiosis Results in production of 2 genetically identical diploid cells Creates all cells in the body EXCEPT gametes PMAT Results in production of 4 genetically different haploid cells Creates gametes Reason why everyone is slightly different EXCEPT for identical twins/triplets PMAT x2 Tetrads form and crossing over happens