The Processes of Mitosis and Meiosis

Note: Quiz over this material tomorrow (Thursday)

Mitosis

• Mitosis- is the process in which a cell divides to form TWO IDENTICAL CELLS.

• Follows specific order of events during the process of mitosis: – Interphase, Prophase, Metaphase, Anaphase,

Telophase.

Step 1: Interphase• Interphase is how the

cell spends a majority of it’s life cycle (up to 90%).

• Normal functions.• When getting ready to

divide, the DNA winds up into chromosomes and duplicates but are NOT in X form yet.

Step 2: Prophase

• The newly created pairs are now visible as the X.

• Start moving to line up in the middle of the cell.

Step 3: Metaphase• Chromosomes, paired up, line up in the

middle of the cell “on top” of each other.

Step 4: Anaphase

• The paired chromosomes divide and pull to each side of the cell, which is beginning to elongate.

Step 5: Telophase• Cell membrane starts pinching off.• Chromosomes start unraveling.

Meiosis

• Process in which sex organs (ovaries and testes) produce FOUR genetically DIFFERENT daughter cells.

• Contains TWO cell divisions.

• Each daughter cell gets HALF the chromosomes as the parent cell.

Prophase I

• DNA winds up, forms into chromosome shapes.

• Each finds it’s “homologous pair”- it’s partner.

Metaphase I

• Line up “on top” of each other, but with it’s homologous partner next to it.

Anaphase I

• Sister chromatids (the X shape) move as a whole to one side or the other.

Telophase I

• Cell membrane begins to pinch off into 2 cells, each with the same number of chromosomes as parent cell.

Prophase II

• Start moving towards middle of cell (again).

Metaphase II

• Chromosomes aligned in middle “on top” of each other. Again.

Anaphase II

• Chromosomes pulled apart, move to opposite sides, again.

Telophase II

• Cell membrane closes off, chromosomes unravel back to DNA strands. Again.

Assignment

• With a partner, create a ‘mnemonic device’ to help you remember– The names of the phases and what occurs in

each.– The differences between Mitosis and Meiosis.

• “Device” can be an acronym, lyrics, rap, poem, or similar thing which can be shared with others in the class.