1. Part 2

2. Cell reproduction of somatic cells (all cells except sperm/egg) This is how we grow, develop, and repair Involves chromosomes: Complex structure of coiled DNA that carries all genetic information (genes)

3. Chromosome # Each species has a characteristic # of chromosomes Humans: 23 pairs (46 total) Dogs: 39 pairs Corn: 20 pairs

4. Diploid: Pairs of similar chromosomes (from parents) Haploid: one of each type of chromosome Gametes (egg 23 / sperm 23) Types: Autosomes: Do not determine sex (1-22) Sex Chromosomes: determine sex (X,Y 23) Male = XY Female = XX

5. Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

6. Longest phase of cell’s life cycle Increase in mass Increase # of organelles Replication of chromosomes (DNA) G1 Phase: Gap prior to DNA replication S Phase: DNA replication G2 Phase: After DNA replication

7. Chromosomes are copied (#doubles) Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and it’s copy (sister chromosome) change to sister chromatids.

8. Mitosis begins (cell begins to divide) Centrioles (poles) appear and move to opposite ends of cell. Spindle fibers form between the poles. Nuclear membrane breaks apart.

9. Chromatids (pairs of chromosomes) attach to the spindle fibers. They are aligned in middle of cell.

10. Chromatids separate and begin to move to opposite ends of the cell.

11. Two new nuclear membranes (nuclei) form. Chromosomes appear as chromatin (threads). Cell membrane begins to pinch together.

12. Cell membrane continues to move inward to create two daughter cells. Each daughter cell has it’s own nucleus with identical chromosomes.

13. Modern Biology Books: Pg. 140 Review ? 1-8 (graded)

14. A type of cell division in which the chromosome # is reduced by half. Production of gametes (sex cells) – these cells have half the # of chromosomes.

15. 2 Major sections of Meiosis: Meiosis I – reductive division Interkinesis – 2 cells form each with only one chromosome from the pair. Meiosis II - Double stranded chromosomes become single stranded chromosomes. Cytokinesis – 4 haploid cells are formed which will become sperm or eggs.

17. Fertilization: Fusion of gametes = reconstitutes the proper # of chromosomes. Trait: Genetic characteristic of an organism. Gene: DNA sequence that codes for a protein (may lead to a trait). Allele: Different forms of a gene.