Cell Division Cells Review What is cell division

Cell Division

• 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 Outline

Cells Review • Cell: smallest part of any living 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 1. Prophase – 1 st step – Nucleus disappears – Chromosomes form (look like X’s) • These are how the DNA is stored in our cells

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

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

4 Steps of Mitosis 4. Telophase – 4 th 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)

What is Cancer? • Cancer: diseases in which mutated body cells divide without control and can invade nearby tissues. – There are more than 100 types of cancer. – Types of cancer are usually named for the organs or tissues where the cancers form. – Examples: breast cancer, lung cancer, skin cancer, testicular cancer

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 1. 2. 3. 4. 5. 6. 7. 8. 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) Reproductive cells (egg and sperm) 4 Types of cells produced # of steps PMAT Step names 2 # of cells produced 4 46 (single) # of chromosomes in cells Comparison to original cell 23 (single) Identical (same DNA) 8 PMAT (1 and 2) ½ the DNA

2 Types of Cell Division in Humans