Sci 9 Lesson 1 Feb 21 - Ch 5.1 The Cell Cycle
- 1. The Cell Cycle Chapter 5.1: The Cell Cycle and Mitosis pp. 150-155
- 3. What am I? A: Dust! What am I really??? A: Dead skin cells! Over 70% of the dust in your home is made up of tiny flakes of skin we lose on a daily basis. Each day, you shed millions of skin cells per hour. Each month, you replace the outer layer (the epidermis) of your skin.
- 4. Note: Terms in green are definitions – these are key terms to know Terms in blue are important words or concepts – please make note
- 5. Introduction to the Cell Cycle Q: Ever wonder how we as humans can grow from a single cell into trillions? How do you think it happens? A: Cells must divide and multiply in number in order to create all of our tissues, organs, organ systems, etc. Cell division allows one cell to become many cells! A single cell (fertilized egg) Billions of cells (single organism)
- 6. Cell Replacement and Development Cells divide as a human body grows. A body must also replace cells that take a lot of wear and tear. Which body cells are replaced most frequently? p. 152 Cell Type Rate Of Cell Division Reason For Cell Replacement Stomach lining cells Every 2 days Destroyed by stomach acid Intestinal lining cells Every 3 days Destroyed by bacteria or during digestion Skin cells Every 20 days Wear and tear during everyday activities or accidents such as scratches
- 7. The Cell Cycle The life of a cell is divided into 3 stages known as the cell cycle : 1 3 Interphase Mitosis Cytokinesis 2 p. 153
- 8. The Cell Cycle interphase : the first and longest stage of the cell cycle, in which cells carry out life functions and cells that divide prepare for cell division mitosis : the second and shortest stage of the cell cycle; the process in which the duplicated contents of the cell’s nucleus divides into two equal parts cytokinesis : the final stage of the cell cycle, which separates the two nuclei and cell contents into two daughter cells
- 9. Interphase interphase : “inter” = between between phases Interphase is the time where the cell obtains nutrients, grows, reads its DNA, and conducts other essential cell functions. Interphase can be divided into 3 parts: Growth and preparation Replication Continued growth and preparation
- 10. Growth and preparation Cell increases in size and makes the proteins and molecules necessary for the cell to function. Some organelles begin to duplicate .
- 11. 2) Replication replication : the cell copies the 3 billion base pairs of DNA information in the nucleus the cell temporarily has two complete sets of DNA Step 1: Enzyme separates DNA sides Step 2: New bases pair with original bases on original DNA Step 3: Two new identical DNA molecules are produced p. 154
- 12. 3) Continued growth and preparation After DNA replication, the cell continues to grow and make materials (ex. proteins) for the future new cells. Chromatin (containing the replicated DNA) is in a loosely coiled form can be copied into RNA proteins can be made. Organelles such as mitochondria and chloroplasts will be duplicated . p. 155
- 13. Activity: Video – Introduction to Mitosis
- 14. Homework for next class: Complete ‘Identifying stages of the cell cycle’ (p. 71 of the worksheet) Answer Reading Check questions 1-6 (p. 155) Complete student questionnaire Bring field trip forms and $ Read over class notes and check out the class blog: http:// msoonscience.blogspot.com /
- 15. Works Cited Images taken from the following sources: http:// www.historyoftheuniverse.com/celldivi.html http:// www.cartoonstock.com/directory/s/single_cell.asp http://www.ias.unt.edu/~tpp001/Mitosis_Diagram_Page.main.html