Cell Division By: Mr. Kauffman

Outline Cells Review What is cell division? Mitosis 4 Steps of Mitosis Results of Mitosis Meiosis 8 Steps of Meiosis Results of Meiosis 2 Types of Cell Division

Cells Review Cell: smallest part of any living thing that carries out the functions necessary to support life Unicellular organism: living thing made up of 1 cell Multicellular organism: living thing made up of many cells

What is cell division? Cell division: a way to produce more cells Usually 1 cell divides to make 2 cells Why is cell division important to multicellular organisms? Its how they grow Replace cells that have died Cancer cell dividing

What is cell division? Why is cell division important to unicellular organisms? Its how they reproduce E. Coli cell dividing

Mitosis Mitosis: process when the cell divides to form 2 identical cells Produces normal body cells Skin and muscle cells The cells produced are identical to each other and to the original cell

Mitosis Mitosis has 4 steps: 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase

4 Steps of Mitosis Prophase 1st step Nucleus disappears Chromosomes form (look like X’s) These are how the DNA is stored in our cells

4 Steps of Mitosis Metaphase 2nd step Chromosomes are lined up in the middle of the cell

4 Steps of Mitosis Anaphase 3rd step Chromosomes are pulled apart ½ of each chromosome goes to each end of the cell

4 Steps of Mitosis Telophase 4th step The cell begins pinching in at the middle Eventually the 1 cell splits to form 2 cells Process is known as cytokinesis Each new cell has its own nucleus and DNA

Results of Mitosis Mitosis produces normal cells in the body Skin and muscle cells 1 cell splits to form 2 cells The new cells are identical to each other (same DNA) The new cells are also identical to the original cell (same DNA)

Meiosis Meiosis: cell division that produces reproductive cells Reproductive cells are also called gametes 2 basic types of gametes (reproductive cells) Females – egg cells Males – sperm cells

Why Meiosis is Needed Fertilization: combining of sperm and egg cells to form a zygote the zygote then grows and develops into a new organism

Meiosis Meiosis has 8 steps Basically goes through mitosis twice There are 2 cell divisions

Meiosis 8 Steps of Meiosis Prophase 1 Metaphase 1 Anaphase 1 Telophase 1 Prophase 2 Metaphase 2 Anaphase 2 Telophase 2

Results of Meiosis Meiosis produces reproductive cells (gametes) Sperm and egg cells 1 cell splits to form 4 cells The 4 new cells have ½ of the DNA that the original cell had Haploid cells: cells with ½ of the amount of DNA of a normal cell Diploid cells: cells with the normal amount of DNA

2 Types of Cell Division in Humans Mitosis Characteristics Meiosis Normal body cells (skin and muscle) Types of cells produced Reproductive cells (egg and sperm) 4 # of steps 8 PMAT Step names PMAT (1 and 2) 2 # of cells produced 4 46 (single) # of chromosomes in cells 23 (single) Identical (same DNA) Comparison to original cell ½ the DNA

2 Types of Cell Division in Humans