1. CELL CYCLE AND MITOSIS Chapter 6, pages 117-132 Vocab Terms: Anaphase, Asexual reproduction, Cell Cycle, Centriole, Clone, Cytokinesis, G1 Phase, G2 Phase, Interphase, Metaphase, Mitosis, Prophase, S Phase, Spindle, Telophase, Tetrad, Centromere, Chromatid

2. Functions of Cell Division 20 µm 100 µm 200 µm (a) Reproduction. An amoeba, a single-celled eukaryote, is dividing into two cells. Each new cell will be an individual organism. (b) Growth and development. This micrograph shows a sand dollar embryo shortly after the fertilized egg divided, forming two cells. (c) Tissue renewal. These dividing bone marrow cells (arrow) will give rise to new blood cells.

3. DNA, Chromatin, Chromatid, and Chromosome... DNA: Genetic material, double helix Chromatin: Network of DNA and Histone proteins Chromatid: One-half of a duplicated chromosome Chromosome: Condensed Chromatin, two sister chromatids

4. CHROMOSOMES Humans have 23 pairs of chromosomes, for a total of 46 chromosomes One set are sex chromosomes XY or XX. Diploid Cells: (Non-Sex Cells) Contains 2 Copies Homologous: A pair of chromosomes, one maternal and one paternal

5. CELL CYCLE

6. INTERPHASE (Cell Cycle) Brown Yarn: Cell Membrane Red Yarn: Nuclear Membrane Buttons: Centrioles Pipe Cleaners: Chromosomes

7. CELL CYCLE/INTERPHASE Phases of the Cell Cycle (24 hours) ◦ Interphase: Prepare the cell for division  G1: a period when the cell grows rapidly and carres out its routine functions. This is the longest phase of the cell cycle. (10 hours)  S: a cell’s DNA is copied during this phase. At the end of this phase, each chromosome is doubled. (5-6 hours)  G2: a period when the cell continues to grow and prepares for the nucleus to undergo division. (3-4 hours) ◦ Mitosis: Cell Division (2 hours)

8. MITOSIS 1 Parent Cell  2 Daughter Cells

9. PROPHASE Green Yarn: Spindle Fibers

10. PROPHASE 1. The DNA condenses and coils up to become visible duplicated chromosomes. 2. Nuclear envelope dissolves. 3. Mitotic spindles form. 4. Centrioles move to opposite poles.

11. METAPHASE

12. METAPHASE 1. Centrioles have migrated to opposite poles. 2. Chromosomes move to the center of the cell and line up along the equator. 3. Spindle fibers link the chromatids of each chromosome to opposite poles.

13. ANAPHASE

14. ANAPHASE 1. Each half of the chromosome moves towards the opposite poles as the spindle fibers attached to them shorten. 2. The cell elongates and each end of the cell has equal amounts of chromosomes.

15. TELOPHASE/CYTOKINESIS Telophase Cytokinesis

16. TELOPHASE/CYTOKINESIS Telophase 1. A nuclear envelope forms around the chromosomes at each pole, forming two separate nuclei. 2. The chromosomes uncoil and become less condensed. 3. Spindle fibers dissolve. Cytokinesis 1. The cytoplasm of the cell is divided in half. 2. The cell membrane grows to enclose each cell, forming two separate cells.

17. CYTOKINESIS: PLANT VS. ANIMAL CELL Animal Cell: ◦ A contractile ring forms that constricts the cells inwards, called a cleavage furrow. Plant Cell: ◦ A cell plate forms down the middle that separates the cell into two.

18. CELL DIVISION: PROKARYOTES (ASEXUAL REPRODUCTION)