1. Cell Division
Why is it important?

2. When you fall and scrape the skin off of your hands or knees, how does your body make new skin cells to replace the skin cells that were scraped off?

3. Life cycles of cells Just like you have a cycle of life- cells do too!
We call it the Cell Cycle
It is the series of events that take place from one cell division to the next
The time it takes to complete 1 whole cycle is not the same for all cells

4. Bean plants
Take about 19 hours to complete 1 cycle

5. Cells in animal embryos
They can complete their cycle in less than 20 minutes!

6. Cells in humans Needed for growth and repair Replacement
Like your skin or bone cells
They constantly repeat this cycle, over and over again

7. The cycle
Interphase
Prophase
Metaphase
Anaphase
telophase

8. Interphase Most of an eukaryotic cells life is spent in interphase
It is just a period of growth and development
A skins cell is an actively dividing cell, and it copies its hereditary material and prepares for cell division during interphase

9. Before a cell divides it has to copy its hereditary material
Each of the new cells will need a copy of this information or blueprint
After interphase, cell division actually starts

10. Cell divison
The nucleus divides, and the cytoplasm seperates to form two new cells
We call the process in which the nucleus divides MITOSIS

11. Cell Division There are 2 types of cell division
Mitosis (almost all cells)
Meiosis (sperm & egg)
The purpose of Mitosis is to produce 2 identical daughter cells
The purpose of Meiosis is to produce haploid cells that contain 23 chromosome- therefore during fertilization you get half of your genes from your mom & half of your genes from your dad

12. Mitosis The nucleus divides into two identical nuclei
Nuclei is plural for nucleus
Kind of like cactus and cacti
The steps of mitosis in order are
Prophase
Metaphase
Anaphase
Telophase

13. Chromosomes Play a VERY important part
A chromosome is a structure in the nucleus that contains all the hereditary material
Each contains one long molecule of DNA
During interphase, each of the chromosome duplicate themselves
When the nucleus is ready to divide, each duplicated chromosome will coil tightly into two thickened, identical strands called chromatids

15. 23 Each human cell has pairs of homologous chromosomes
This is VERY important! When we study meiosis, one tiny mistake can result in Down’s Syndrome 23

16. Each cell in your body has 2 copies of a chromosome
These copies are called homologous chromosomes
Because the contain the SAME genes at the same locations
HOWEVER- they may have different versions of a gene (we call these alleles)
Ex: Normal skin & hair color/very pale skin & hair color (albino)

17. prophase
The pairs of chromatids are fully visible when viewed under a microscope

18. Metaphase
Chromosome line up in the center of the cell

19. Anaphase
The chromosome seperate

22. Telophase
The final Step! The cytoplasm is beginning to separate to form 2 cells now