Section Outline 10–1 Cell Growth Cell Division A. Limits to Cell Growth 1. DNA “Overload” 2. Exchanging Materials 3. Ratio of Surface Area to Volume 4. Cell Division Cell Division Go to Section:

Limits to Cell Growth Why do cells need to divide? Too much demand on its DNA (DNA overload) As it grows it doesn’t make extra DNA (question #2) Analogy (one library in Chicago) Exchanging materials (food and oxygen in) (wastes out) oxygen waste mito

Ratio of Surface Area to Volume in Cells Section 10-1 Cell Size Surface Area (length x width x 6) Volume (length x width x height) Ratio of Surface Area to Volume 3. A cell’s volumes determines the rate at which food is used and wastes produces Go to Section:

Surface Area to Volume Ratio SA/Vol =6:10 or 3:5 10 10 10 6. As the cell grows its volume increases much more rapidly than its surface area, therefore… 7. a. The surface area to volume ratio decreases

Cell Division Cell Division 8. Cell division is the process by which a cell divides into “daughter cells” 9. Reduces the volume and increases overall surface area

Section Outline 10–2 Cell Division A. Chromosomes B. The Cell Cycle C. Events of the Cell Cycle D. Mitosis 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase E. Cytokinesis Go to Section:

Chromosomes Chromosomes – Made up of DNA (carries genetic material) Must be copied before cells can divide 1. True – not visible prior to cell division 2. Before cell division chromosomes become visible. Consists of two identical sister chromatids (copied chromosomes) chromosome 3. Sister chromatids

Figure 10–4 The Cell Cycle 4. Period of growth in between Section 10-2 4. Period of growth in between cell divisions 9. Cell do most of their growing making proteins G1 phase (grow) M phase 10. Chromosomes copied (DNA) S phase (synthesis) Division of cell nucleus during M phase G2 phase 11. Organelles required for M phase produced 5. Cell cycle is series of events that cells go through as they grow and divide Go to Section:

(Cell Division) Concept Map Cell Cycle Section 10-2 Go to Section: includes (Cell Division) Mitosis Interphase Cytokinesis is divided into is divided into G1 phase S phase Prophase G2 phase Metaphase Telophase Anaphase Go to Section:

Onion Root Tip http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html

Mitosis – Dividing of Cell Nucleus Prophase Metaphase Anaphase Telophase Key terms: 13. Centrioles - structures that make spindle fibers 14. Spindle fibers – structure responsible for separating chromatids

Spindle fibers Prophase (key events) Chromosomes become visible Nucleus begins to disappear spindle fibers are formed from centrioles centrioles

Metaphase 19. The chromosomes line up across the center of the cell (moving along spindle fibers)

Anaphase 15. Chromosomes pulled apart (sister chromatids) until they form two groups near the “poles” of the spindle

Telophase The nucleus begins to reform around each cluster of chromosomes Cytokinesis – Division of cytoplasm. Cell membrane or Cell plate is formed in between nuclei

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming Go to Section:

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming Go to Section:

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming Go to Section:

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming Go to Section:

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming Go to Section:

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming Cell Division Go to Section:

Understanding Chromosomes in Humans Section 11-4 Chromosomes in Human Cells How Many Chromosomes? Normal human body cells each contain 46 chromosomes. The cell division process that body cells undergo is called mitosis and produces daughter cells that are virtually identical to the parent cell. 46 46 mitosis 46 Go to Section:

Understanding Chromosomes in Humans Chromosomes in Human Cells Where did we get our chromosomes? From our parents How many did you get from your father? typically 23 How many did you get from your mother? We often say that you got a set of chromosomes (23) from your mother and a set of chromosomes (23) from your father.

Homologous Chromosomes Chromosomes in Human Cells The set from your mother and the set from your father are called homologous chromosomes! Why are they called homologous? Because each set contains the same (homo) basic genetic information.

Homologous Chromosomes Blue eye gene Brown eye gene From Mom From Dad Blonde hair gene Brown hair gene

Human cell with all its chromosomes cytoplasm nucleus

Introduction to Meiosis Process by which sex cells (gametes) are formed sperm cells or pollen cells (male cells) egg cells (female cells) Cell division of sex cells whereby, homologous chromosomes are separated

mitosis 46 Zygote (2n) fertilization Diploid 2n 46 Diploid 2n 46 Meiosis Meiosis 23 23 23 23 Haploid 1n Haploid 1n sperm eggs

Meiosis I

Crossing over during prophase I adds to genetic variaility A = blonde hair a = brown hair C = blue eyes c = brown eyes

Meiosis II

Polar Bodies

Genetic Variablity Sexual Reproduction increases genetic variability by Crossing over of sister chromatids during prophase I Independent assortment during metaphase I Random Fertilization