1. Cell Processes Mitosis and Meiosis

2. Cell Cycle The cell cycle is a regular sequence of growth and division that cells undergo.

3. Stage 1: Interphase Cells grow to its full size Make an exact copy of its DNA –DNA is found in chromatin Centrioles are also copied Prepare to divide into two cells

4. Stage 2: Mitosis Division of cytoplasm into two new (daughter) cells Mitosis is divided into 4 parts –Prophase –Metaphase –Anaphase –Telophase

5. The Cell Cycle Prophase- –chromatin condense to form chromosomes. –Pairs of centrioles move to opposite side of the nucleus. –Spindle fibers form a bridge between the ends of the cell. –The nuclear envelope breaks down.

6. The Cell Cycle Metaphase- –Chromosomes line up across the center of the cell. –Chromosome attaches to a spindle fiber at its centromere

7. The Cell Cycle Anaphase –Centromeres split. –The two chromatids separate and each chromatid becomes a new chromosome. –The new chromosome move to opposite ends. – The cell stretches out as the opposite ends are pushed apart.

8. The Cell Cycle Telophase –Chromosomes begin to stretch out and lose their rod-like appearance. –A new nuclear envelope forms around each region of the chromosomes Stage 3- Cytokinesis –The cytoplasm divides and the organelles are distributed into each of the two cells.

9. The Cell Cycle

11. DNA DNA has four kinds of nitrogen bases: –A (adenine) –T (thymine) –G (guanine) –C (cytosine) Only A and T pair Only G and C pair

12. The Replication Process DNA replication begins when the two sides of the DNA molecule unwind and separate, like a zipper unzipping. Next, nitrogen bases that are floating in the nucleus pair up with the bases on each half of the DNA molecule. Once the new bases are attached, a new DNA molecule had formed.