1. Cell Growth & Division
Mitosis

2. Why do Cells Reproduce? Growth of an organism
Replacement of old or damaged cells

3. Chromosomes
Each cell has lots of DNA, but it must be condensed in order to fit in the nucleus
DNA is organized and packaged into structures called chromosomes
Prokaryotic Chromosome:
Single circular strand of DNA that is condensed through many twists
Eukaryotic Chromosome…

4. Eukaryotic Chromosomes
Most eukaryotes have between 10 & 50 chromosomes in their body cells, but…
Chromosomes can’t be seen when cells aren’t dividing and are called chromatin

5. Eukaryotic Chromosomes
When cells are ready to divide, the chromatin condenses into chromosomes
Each of the 2 thick strands is called a chromatid
Identical chromatids (sister chromatids) are held together at centromere

6. Preparing for Cell Division
All newly-formed cells require DNA, so before a cell divides, a copy of DNA is made for each new cell (daughter cell)
This assures that new cells will work in the same way as the cells they came from

7. Preparing for Cell Division
In prokaryotic cells, it’s simple!! DNA is copied, then cell divides
In eukaryotic cells, it’s more complex…

8. Eukaryotic Cell Cycle: Overview
1.) Interphase: when cell grows and prepares to divide
2.) Mitosis: when nucleus divides
3.)
Cytokinesis: when cytoplasm divides and two new cells are complete

9. Two identical copies of DNA
Interphase
Growth stage
Cells mature by making more cytoplasm
Organelles and Centrioles duplicate
DNA is copied
Two identical copies of DNA
Original DNA

10. Mitosis
Prophase
Metaphase
Anaphase
Telophase
PMAT!!

11. Prophase Chromatin in nucleus condenses to form visible chromosomes
Spindle fibers form from the centrioles and attach to centromeres

12. Metaphase
Chromosomes that are attached to spindle fibers move to the center of the cell and line up

13. Anaphase Occurs Rapidly
Sister chromatids are pulled apart to opposite poles of cell by spindle fibers

14. Telophase Sister chromatids are at opposite poles Spindles disassemble
Nuclear envelope forms around each set of sister chromatids

15. Cytokinesis Division of cytoplasm
Division of cell into two, identical cells called daughter cells
Daughter cells have the same # of chromosomes as each other and as the parent cell from which they were formed
Must still grow in size to become mature

16. Onion Root Tip Prophase Prophase Interphase Prophase Interphase
Anaphase
Telophase
Cytokinesis
Metaphase
Anaphase

17. Animation: