CELL DIVISION MITOSIS and the Cell Cycle MITOSIS and the Cell Cycle

MITOSIS Mitosis is the process used by most cells to reproduce. Asexual Reproduction: only needing one parent Mitosis is the process used by most cells to reproduce. Asexual Reproduction: only needing one parent During Mitosis, the cell makes an exact copy of itself and its genetic material During Mitosis, the cell makes an exact copy of itself and its genetic material This genetic material is sometimes referred to as the genes or DNA (deoxyribonucelic acid) of the cell. This genetic material is sometimes referred to as the genes or DNA (deoxyribonucelic acid) of the cell. The genes are found on the chromosomes of the cell, located inside the nucleus. The genes are found on the chromosomes of the cell, located inside the nucleus. Mitosis occurs in many stages, Mitosis occurs in many stages, called “phases”… called “phases”…

INTERPHASE This is the first phase… This is the first phase… The cell is preparing for Mitosis The cell is preparing for Mitosis Chromosomes duplicate themselves. Chromosomes duplicate themselves. Cell begins to grow. Cell begins to grow.

PROPHASE This is the second phase of Mitosis… This is the second phase of Mitosis… The nuclear membrane disappears. The nuclear membrane disappears. Chromosomes form and appear “tangled.” Chromosomes form and appear “tangled.” Spindle fibers form and attach to the chromosomes. Spindle fibers form and attach to the chromosomes.

METAPHASE The third phase of Mitosis. The third phase of Mitosis. Fibers pull on doubled chromosomes Fibers pull on doubled chromosomes Chromosomes “line up” in the middle of the cell. Chromosomes “line up” in the middle of the cell.

ANAPHASE This is the fourth phase of Mitosis. This is the fourth phase of Mitosis. Chromosomes are being pulled apart Chromosomes are being pulled apart Chromosomes move to opposite ends of the cell just before separation occurs. Chromosomes move to opposite ends of the cell just before separation occurs.

TELOPHASE Fifth and final phase of Mitosis. Fifth and final phase of Mitosis. Spindle fibers disappear. Spindle fibers disappear. Nuclear membrane forms around each set of chromosomes. Nuclear membrane forms around each set of chromosomes. 2 new cells are formed 2 new cells are formed

MITOSIS MOVIE

Microscopic Cells Showing Mitosis

MEIOSIS

What is MEIOSIS???? MEIOSIS is a special kind of cell division that is needed for sexual reproduction. MEIOSIS is a special kind of cell division that is needed for sexual reproduction. Meiosis creates egg cells in females and sperm cells in males. Meiosis creates egg cells in females and sperm cells in males. Meiosis Diagram Meiosis Diagram Meiosis Diagram Meiosis Diagram

HOW DOES THIS WORK??? Each of you started off as a fertilized egg (2n) Each of you started off as a fertilized egg (2n) ½ of your DNA came from mom’s egg and the other ½ of your DNA came from dad’s sperm ½ of your DNA came from mom’s egg and the other ½ of your DNA came from dad’s sperm 1n (mom) + 1n (dad) = 2n (you!) 1n (mom) + 1n (dad) = 2n (you!) MEIOSIS is a special kind of cell reproduction that produces (a single set of chromosomes)sperm and egg cells MEIOSIS is a special kind of cell reproduction that produces (a single set of chromosomes)sperm and egg cells

MEIOSIS is Mitosis, only TWICE! Has all the same phases as Mitosis… Interphase, Prophase, Metaphase, Anaphase and Telophase… Has all the same phases as Mitosis… Interphase, Prophase, Metaphase, Anaphase and Telophase… Meiosis 1 produces two new cells Meiosis 1 produces two new cells Meiosis 2 splits those two cells into four new cells with only a single set of chromosomes. Meiosis 2 splits those two cells into four new cells with only a single set of chromosomes.

IMPORTANT DIFFERENCES… Only Cells that become gametes (eggs or sperm) undergo meiosis. Only Cells that become gametes (eggs or sperm) undergo meiosis. Cells that undergo meiosis go through two cell divisions, so one cell becomes 4 cells in the end… Cells that undergo meiosis go through two cell divisions, so one cell becomes 4 cells in the end… Meiosis makes haploid (single set of chromosomes) cells, while Mitosis makes diploid (full set of chromosomes) cells. Meiosis makes haploid (single set of chromosomes) cells, while Mitosis makes diploid (full set of chromosomes) cells. Cells which undergo Mitosis are EXACT COPIES of the original cell. Cells then undergo Meiosis then get sperm and egg cells. Cells which undergo Mitosis are EXACT COPIES of the original cell. Cells then undergo Meiosis then get sperm and egg cells.

Meiosis Movie

Diagram of Mitosis and Meiosis

Mitosis Picture

Meiosis Picture

Comparison Diagram