CELL DIVISIONCELL DIVISION

MITOSIS MITOSIS and the and the Cell Cell CycleCycle

MITOSISMITOSIS Mitosis is the process used by most cells to Mitosis is the process used by most cells to

reproduce. reproduce. Asexual ReproductionAsexual Reproduction: only : only needing one parentneeding one parent

During Mitosis, During Mitosis, the cell makes an exact the cell makes an exact copy of itself and its genetic materialcopy of itself and its genetic material

This genetic material is sometimes referred This genetic material is sometimes referred to as the to as the genesgenes or or DNADNA ( (deoxyribonucelic deoxyribonucelic acidacid) of the cell.) of the cell.

The genes are found on the The genes are found on the chromosomeschromosomes of the cell, of the cell, located inside the nucleus.located inside the nucleus.

Mitosis occurs in many stages, Mitosis occurs in many stages, called “called “phasesphases”…”…

INTERPHASEINTERPHASE This is the first This is the first

phase…phase… The cell is The cell is

preparingpreparing for for MitosisMitosis

Chromosomes Chromosomes duplicate duplicate themselves.themselves.

Cell begins to growCell begins to grow..

PROPHASEPROPHASE This is the second phase of This is the second phase of

Mitosis…Mitosis… The nuclear The nuclear

membrane membrane disappears.disappears.

Chromosomes form Chromosomes form and appear and appear “tangled.”“tangled.”

Spindle fibers form Spindle fibers form and attach to the and attach to the chromosomes.chromosomes.

METAPHASEMETAPHASE The third phase of The third phase of

Mitosis.Mitosis.

Fibers pull on Fibers pull on doubled doubled chromosomeschromosomes

Chromosomes “line Chromosomes “line up” in the middle of up” in the middle of the cell.the cell.

ANAPHASEANAPHASE

This is the fourth phase of Mitosis.This is the fourth phase of Mitosis.

Chromosomes are being pulled apartChromosomes are being pulled apart

Chromosomes move to opposite ends of the cell Chromosomes move to opposite ends of the cell just before separation occurs.just before separation occurs.

TELOPHASETELOPHASE Fifth and final Fifth and final

phase of Mitosis.phase of Mitosis. Spindle fibers Spindle fibers

disappear.disappear. Nuclear membrane Nuclear membrane

forms around each forms around each set of chromosomes.set of chromosomes.

2 new cells are 2 new cells are formedformed

MITOSIS MOVIEMITOSIS MOVIE

Microscopic Cells Showing MitosisMicroscopic Cells Showing Mitosis

MEIOSISMEIOSIS

What is MEIOSIS????What is MEIOSIS???? MEIOSIS is a special kind of cell MEIOSIS is a special kind of cell

division that is needed for sexual division that is needed for sexual reproduction.reproduction.

Meiosis creates Meiosis creates egg cellsegg cells in females and in females and sperm cellssperm cells in males. in males.

Meiosis DiagramMeiosis Diagram

HOW DOES THIS WORK???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 ½ of your DNA came from mom’s egg and the other ½ of

your DNA came from dad’s spermyour 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 MEIOSIS is a special kind of cell reproduction that produces

(a single set of chromosomes)sperm and egg cells(a single set of chromosomes)sperm and egg cells

MEIOSIS is Mitosis, only TWICE!MEIOSIS is Mitosis, only TWICE!

Has all the same phases as Mitosis… Has all the same phases as Mitosis… Interphase, Prophase, Metaphase, Anaphase Interphase, Prophase, Metaphase, Anaphase and Telophase…and Telophase…

Meiosis 1Meiosis 1 produces two new cells produces two new cells Meiosis 2Meiosis 2 splits those two cells into four new splits those two cells into four new

cells with only a single set of chromosomes.cells with only a single set of chromosomes.

IMPORTANT DIFFERENCES…IMPORTANT DIFFERENCES… Only Cells that become Only Cells that become gametesgametes (eggs or sperm) (eggs or sperm)

undergo meiosis.undergo meiosis. Cells that undergo meiosis go through two cell Cells that undergo meiosis go through two cell

divisions, so one cell becomes 4 cells in the end…divisions, so one cell becomes 4 cells in the end… Meiosis makes haploid (single set of chromosomes) Meiosis makes haploid (single set of chromosomes)

cells, while Mitosis makes diploid (full set of cells, while Mitosis makes diploid (full set of chromosomes) cells.chromosomes) cells.

Cells which undergo Mitosis are EXACT COPIES of Cells which undergo Mitosis are EXACT COPIES of the original cell. Cells then undergo Meiosis then get the original cell. Cells then undergo Meiosis then get sperm and egg cells.sperm and egg cells.

Meiosis MovieMeiosis Movie

Diagram of Mitosis and MeiosisDiagram of Mitosis and Meiosis

Mitosis PictureMitosis Picture

Meiosis PictureMeiosis Picture

Comparison DiagramComparison Diagram