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Mitosis and Meiosis. Why do we look similar to but different than our siblings?. Before mitosis OR meiosis…. Chromosomes duplicate (make a copy of themselves). Mitosis. Fibers attach to chromosomes Chromosomes line up along the middle of the cell Chromosomes pulled to opposite ends of cell
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Mitosis and Meiosis Why do we look similar to but different than our siblings?
Before mitosis OR meiosis… • Chromosomes duplicate (make a copy of themselves)
Mitosis • Fibers attach to chromosomes • Chromosomes line up along the middle of the cell • Chromosomes pulled to opposite ends of cell • New nuclear membranes form around chromosomes • Two new daughter cells are formed
Key points in mitosis • Two daughter cells are produced that are genetically identical to the original cell • A typical human cell has 46 chromosomes. How many chromosomes do the daughter cells have after mitosis? • Mitosis happens in the body for: • Growth • Repair • Replace old or damaged cells
Cell division of reproductive cells • What would happen if the sperm and the egg were produced through mitosis? • This is why reproductive cells are created through a type of cell division called meiosis
Meiosis I • Pairs of duplicated chromosomes randomly line up along the middle of the cell • Duplicated chromosomes move away to opposite sides of cell
Meiosis II • Chromosomes line up along the center of the cell • Two strands of each chromosome separate and move to opposite ends
Results of meiosis • Four genetically different cells are produced • Each sex cell has HALF the number of chromosomes of the parent cell
How does meiosis promote genetic variation? • Each cell has a different combination of chromosomes • Chromosomes can exchange genes during meiosis = new combinations • Each parent only contributes half of the chromosomes to offspring
Comparing mitosis and meiosis Similarities Differences