1. Chapter 8 Notes

2. Mitosis  Cells must divide: 1.to keep the surface to volume ratio manageable 2.because if cells get too large, they can not eliminate wastes and bring in proper nutrition.

3. Diploid – 2 sets of chromosomes (ex. 46 in human body cells) – 2n Haploid – 1 set of chromosomes (ex. 23 in human sex cells) - n

4. Chromatin and Chromosomes  Chromatin is the thin, threadlike DNA found when the cell is not dividing.  Chromosomes are the thick coiled visible form of DNA found during cell division.  Chromosome

5.  Study handout. Be able to name and describe each phase and division in cell cycle (front).  Know the order of the phases, and know the labeled structures in mitosis (back).

6. DNA  In prokaryotic cells, the circular chromosome (DNA) floats in the cytoplasm.  In eukaryotic cells, sets of chromosomes in different lengths (DNA) are found in the nucleus of the cell.

7. Cell Cycle  During the cell cycle, a cell grows, replicates (copies) all of its DNA, and divides into two daughter cells, which each receives an exact copy of the parent cell’s DNA.  In humans, parent cells have 46 chromosomes, so each daughter cell will have 46 chromosomes.

8. Cell Cycle  There are 2 main parts of the cell cycle:  1. interphase  2. cell division (mitosis and cytokinesis  Interphase is the part of the cell cycle in which the cell is growing and carrying out its function. This is when the cell is doing its job

9. Cell Cycle  There are 2 main parts of the cell cycle:  1. interphase  2. cell division (mitosis and cytokinesis  Mitosis is the division of the nucleus  Cytokinesis is the division of the cytoplasm.

10. Interphase  3 phases of interphase:  1. G1 – Cell growth  2. S – DNA replication  3. G2 – preparation for mitosis; organelles are produced  G1-  S  G2  M  C End part 1

12. Mitosis - Prophase  PROPHASE:  Chromatin condenses into chromosomes  Nuclear membrane is broken down  Spindle fibers form

13. Mitosis - Metaphase  METAPHASE:  Chromosomes line up in the MIDDLE of the cell.

14. Mitosis - Anaphase  ANAPHASE:  The sister chromatids separate and move APART toward the opposite sides of the cell.

15. Mitosis - Telophase  TELOPHASE:  Chromosomes uncoil into chromatin.  Two new nuclear membranes form.  Opposite of prophase.

16. Cytokinesis  CYTOKINESIS:  The cell membrane and cytoplasm divide  In plant cells, a cell plate is formed, which turns into a new cell wall.  Animal cells pinch in half.  Result of mitosis: 2 daughter cells that are exactly like the parent cell

17. A karyotype shows the number of chromosomes and whether it is a boy or girl. Gamete – sex (reproductive) cell – egg or sperm (or pollen) – haploid Somatic cell – body cell - diploid

18. In meiosis, crossing over takes place when homologous chromosomes exchange segments of DNA.