Cell Division: Mitosis vs. Meiosis

1. Learning Target: You will need: Pencil Science notebook Highlighter Today is Wednesday 2/6 • I can explain why cells divide and describe the 2 types of cell division.

2. What happens when you get a cut or scrape? How does your body heal?

3. How do living things grow?

4. Do cells live forever? How do we get new cells?

5. In the reading yesterday… what did they mean by “Life comes from life?” Hint: it’s #4

6. CELLS DIVIDE But… why and how?

7. What are mitosis and meiosis? • What occurs at different phases in cell division? • How are mitosis and meiosis similar and different? Essential Questions:

8. Chromosome: Tightly packed DNA, occurs in pairs. • Diploid cell: same genetic makeup as the parent cell • Haploid cell/gamete/sperm cell/egg cell: genetically different from parent cells, half the chromosomes (23) • Body cell: 46 chromosomes • DNA Deoxyribonucleic acid): stores information and tells the cells what proteins to make and when. • Gene: units of DNA that tell the cell to make a certain protein. Glue in Vocab

9. Growth and Repair: Reproduction: Creates offspring with traits from both mother and father. Meiosis – Meiosis makes Me Creates gametes (aka: haploid cells, egg, or sperm) Occurs in gamete-producing cells. Cells divide for 3 reasons: Growth, Repair, and Reproduction. • Creates an exact copy of the cell. • Allows living things to grow and new cells to replace damaged or dead cells. • Mitosis – like a copy machine. • Occurs in body cells

10. 4 basic stages that happen in a strict order. • Produces diploid cells = cells with the same genetic makeup of the parent cell (46 chromosomes and they are all identical) • Prophase: chromosomes form and replicate • Metaphase: chromosomes line up in the center of the cell and spindle fibers attach to them. • Anaphase: chromosomes are pulled apart and move to the opposite ends of the cell. • Telophase: cell divides and nucleus forms around DNA • Interphase: waits until next division. Mitosis – division for growth and repair where cells are copied exactly.

11. chromosomes line up in the center of the cell and spindle fibers attach to them chromosomes are pulled apart and move to the opposite ends of the cell chromosomes form and replicate cell divides and nucleus forms around DNA

13. Cells divide for ______________, _______________, and ____________. • Mitosis is like a ___________________. • Mitosis creates 2 _______ cells. Let’s Review! growth repair reproduction Copy machine diploid

14. Reduces the # of chromosomes by ½. • Why would this be important? • Produces 4 gamete cells (aka haploid cells, aka sperm/egg cells) that are genetically different from parent cells and unique. • 2 sets of stages: Meiosis 1 and Meiosis 2 • Meiosis 1: Similar to Mitosis • Meiosis 2: Another round of the cell cycle except DNA is not copied and the daughter cells from Meiosis 1 divide to form 4 unique cells (gametes, haploid cells, sperm/egg) Meiosis – division for reproduction that creates 4 haploid cells that are all unique and have ½ the chromosomes of the original cell.

15. # of chromosomes

16. Review Why do cells divide?

18. Can you… • Define mitosis and meiosis? • Identify what occurs at the different phases in cell division? • Recognize the similarities and differences between mitosis and meiosis? Check for understanding:

19. Complete the organizer using the following words: • Body cell • Gamete producing cell • Diploid cell • One-cell division • 2 cell divisions • The same • Half • Chromosomes • Original cell • 4 haploid cells Mitosis vs. Meiosis