What is this crazy woman talking about?! Just in Time What is this crazy woman talking about?!

Cell Division Simply put, mitosis is cell division Cells divide for several reasons To allow organisms to grow To replace old/dying cells To repair damaged tissue

The Cell Cycle This is a series of events that takes place from one cell division to the next It consists of several phases Interphase: The longest part of the cycle Mitosis: The division of the nucleus Cytokinesis: The division of the cytoplasm

Interphase Cells spend most of their life in this phase It is a period of growth and development The cell duplicates its chromosomes in preparation of cell division

Mitosis This is when the nucleus divides into two nuclei (in body/somatic cells) It is divided into 4 phases Prophase Metaphase Anaphase Telophase

Prophase The nucleolus and nuclear membrane break down and disintegrate The chromosomes become visible with a light microscope Centrioles move to the poles of the cell Spindle fibers begin to form

Metaphase The pairs of (or sister) chromatids line up across the center of the cell The spindle fiber attaches to the centromeres

Anaphase The sister chromatids are pulled apart to opposite poles of the cell

Telophase The spindle fibers begin to disappear Two new nuclei begin to form The cytoplasm begins to pinch apart

Cytokinesis This is the division of the cytoplasm In animal cells, the cell membrane pinches in the middle and the cytoplasm divides In plant cells, a cell plate forms This becomes the cell wall New cell membranes form from the cell plate

Sexual Reproduction This occurs when two sex cells (gametes) come together These two cells are usually a sperm and an egg When these two cells unite, it is called fertilization After fertilization, cell division begins to make a new organism

Lets talk numbers Body cells (somatic cells) are diploid because they contain 23 pairs (46) chromosomes Sex cells (gametes) are haploid because they contain 23 single chromosomes

Meiosis This is the process that produces haploid sex cells This ensures that offspring are diploid Meiosis is divided into two parts Meiosis I Meiosis II

Meiosis I It is almost identical to mitosis The genetic material duplicates itself The steps are: Prophase I Metaphase I Anaphase I Telophase I

Meiosis II There is no interphase before meiosis II begins It goes straight from telophase I to prophase II The steps are: Prophase II Metaphase II Anaphase II Telophase II

In the end… You will have 4 haploid sex cells