The Importance of Cell Division

What is the purpose of cell division?

1. Healing & Tissue Repair You don’t go through life with the same cells you had at birth Every second, millions of your cells are injured or die New cells replace dead cells What are some daily activities that remove cells?

Interesting Fact! If you were to examine the filter in your furnace about 50% of the dust would actually be dead human cells!

2. Growth Increasing the number of cells Human growth begins with the division of a single fertilized egg cell Instead of dividing, why don’t cells just get bigger? The distance from the nucleus to the organelles must be kept short so they can communicate

3. Reproduction Cell division creates new organisms Ex. Bacteria that divide in two

How long do cells live?? Red blood cells = 120 days White blood cells = 13 days http://www.brainpop.com/ (blood) Top layer Skin cells= 30 days Brain cells rarely divide to make new cells, so be nice to the ones you have!

Interesting Fact ! Elizabeth Bathory 1560-1614 Countess Dracula Used to kill all the young maidens around Hungary to bath and drink their blood. young people’s blood = keep her youthful. She killed 612 people Why would she be wrong in her thoughts of using young peoples blood to stay youthful?

Review 1) Why is cell division important? 2) Give examples that show how cells in your body divide at different rates. 3) At one time, doctors transfused blood from younger people to the elderly. They believed that the younger blood would provide the elderly with more energy. Do older people actually have older blood? Think about what we talked about in class to support your answer.

How do cells divide ? Mitosis Meiosis Everywhere in your body Except in your reproductive organs Makes two daughter cells that are exact copies of original Meiosis Only happens in your reproductive organs Makes 4 daughter cells that are all unique and different from original Why?

Mitosis Foldable Create your own notes using the textbook pages provided and the diagram from the board. Cut out each side and glue them into your note book or back to back. Be neat! You are expected to know all the stages of mitosis and identify them. Use mine as a template if you feel like you are stuck.