What is meiosis?

• During meiosis one cell? divides twice to form four daughter cells.
• These four daughter cells only have half the number of chromosomes? of the parent cell – they are haploid.
• Meiosis produces our sex cells or gametes? (eggs in females and sperm in males).

Mitosis occurs only in eukaryotic cells. Prokaryotic cells, which lack a nucleus, divide by a different process called binary fission. Most human cells are produced by mitotic cell division. Important exceptions include the gametes – sperm and egg cells – which are produced by meiosis.

The daughter cells produced by mitosis are identical, whereas the daughter cells produced by meiosis are different because crossing over has occurred. The events that occur in meiosis but not mitosis include homologous chromosomes pairing up, crossing over, and lining up along the metaphase plate in tetrads.

Mitosis creates two identical daughter cells that each contain the same number of chromosomes as their parent cell. In contrast, meiosis gives rise to four unique daughter cells, each of which has half the number of chromosomes as the parent cell.

The fastest cells moved about 15 micrometers—that’s one body length of a cell—in a little less than one minute. Theriot said, “This seems slow to us, but is fast for a cell.” A curved portion on the front of each cell stuck out like the bill of a baseball cap and was larger in some cells than in others.

Most cells in the body are normally locked to their neighbors, tightly embedded in a tissue. Their connections to their neighbors depend on fibers built from long chains of a protein called actin. This not only allows the cells to move, but also changes their form, because actin fibers give the cell its basic shape.

All living cells need energy to function in order for the chemical reactions occurring in the cells to take place. In humans this energy is obtained by breaking down organic molecules such as carbohydrates, fats and proteins.