1. Get fill-in the blank notes from the front and your spiral. I EXPECT FOR ALL STUDENTS TO BE IN THEIR CHAIRS WHEN THE BELL RINGS!

2. The Cell Cycle Interphase, Mitosis and Cytokinesis

3. Cell Reproduction- Intro Infromation Recall that the cell theory states that all cells come from preexisting cells. Cellular division is the process by which new cells are produced from one cell. This results in two cells that are identical to the original, parent cell.

4. Right now, as you are reading this page, many of the cells in your body are growing, dividing, and dying. Old skin cells are being shed and replaced, cuts and bruises are healing. Worn-out tissues are repaired or replaced by newly produced cells.

5. Discovery of Chromosomes Early biologists observed that just before cellular division, several short, stringy structures suddenly appeared in the nucleus. Scientists also noticed that these structures seemed to vanish soon after division of the cell. These structures are chromosomes.

6. Chromosomes are the carriers of the genetic material (DNA) that is copied through DNA replication so that each new cell has the correct genetic material in it.

7. Anatomy of a Chromosome For most of a cell’s lifetime, chromosomes exist as chromatin, long strands of DNA wrapped around proteins called histones. Under a microscope, chromatin looks like beads on a string.

8. Anatomy of a Chromosome An unduplicated chromosome is called a chromatid. When two identical chromatids are together (sister chromatids), this is called a duplicated chromosome. These sister chromatids are held together by a centromere

9. In the body cells of animals and most plants, chromosomes occur in pairs. With the sister chromatids together. One chromosome in each pair came from the male parent, and the other came from the female parent.

10. Humans have 46 chromosomes or 23 pairs. The 23 rd pair are our sex chromosomes that make you male or female.

11. Cells with two of each kind of chromosome are called diploid cells. The prefix dipl- means double These are said to contain a diploid, or 2n, number of chromosomes. “n” stands for the number of duplicated chromosomes. This number multiplied by the 2 =the total number of chromosomes for the cell.

12. Organisms produce gametes or reproductive cells. – Ex. Humans produce gamete cells which are eggs for females and sperm for males. These cells contain one of each kind of chromosome and are called haploid cells said to contain a haploid, or n, number of chromosomes. The prefix hapl- means single Look at table 10.1 in your book on p. 265.

13. This process of making gametes or reproductive cells is called meiosis. We will talk in detail about meiosis later. For now you just need to understand the following: – Our body cells (non-reproductive cells) are diploid cells – Our egg and sperm (reproductive cells) are haploid cells

14. Cell Cycle During the cell cycle, a cell grows, prepares for division, and divides to form 2 daughter cells, each of which then begins the cycle again.

15. There are three main parts to the cell cycle. 1.Interphase a. G1, S, G2 2.Mitosis a. Prophase, Metaphase, Anaphase and Telophase 3.Cytokinesis

16. 1. Interphase Interphase – Most of the cells life is spent in interphase. – G1 (Gap 1)= Rapid growth and metabolic activity Check point to make sure the conditions are correct to support DNA replication – S (Synthesis)=DNA replicates – G2 (Gap 2)= Cell prepares to divide Second check point where the cell makes sure that the DNA and other cell parts were replicated correctly.

17. 2. Mitosis The division of somatic or regular cells. Its divided into 4 phases. – PMAT Prophase (prefix Pro- means 1 st ) Metaphase (prefix Meta- means middle) Anaphase (prefix Ana- means opposite) Telophase (prefix Telo- means end)

18. Prophase First stage Chromatin condenses into chromosomes Centrioles separate and spindle fibers begin to form. Nuclear membrane breaks down

19. Metaphase Second Phase of Mitosis Chromosomes line up in the middle of the cell. Each chromosome is connected to a spindle fiber.

20. Anaphase Third Phase of Mitosis The sister chromatids separate into individual chromosomes and move apart to opposite ends of the cell.

21. Telophase The end or Final Stage of Mitosis Chromosomes gathered at opposite ends of the cell and lose their distinct shapes Two new nuclear membranes have formed.

22. 3. Cytokinesis The cytoplasm pinches in half. Each daughter cell has an identical set of duplicate chromosomes