Cell Reproduction The Cell Cycle and Cell Division

Essential Question: Am I immortalized by my DNA?

Objectives Describe the four phases of the cell cycle and how they are controlled. Describe what a chromosome is and how it looks. Explain what cancer is. Describe the states of mitosis and compare and contrast mitosis in plant and animal cells. Describe how the cell cycle is regulated.

Cell Division in Prokaryotes Division occurs by the process of “binary fission” caused by the growth of new plasma membrane between the duplicated chromosome.

Cell Division in Eukaryotes Unicellular eukaryotes divide in a similar fashion to prokaryotes. Small, multicellular eukaryotes divide in a process called “budding”. A bud of dividing cells grow off the side of the parent The bud develops into a small replica of the parent and eventually breaks off to live on its own. Budding Green Hydra

Cell Division of Complex Eukaryotes How do complex, multicellular organisms grow? The growth and division of cells, MANY TIMES Q: Why is it necessary for growth to occur by the division of cells instead of cells merely becoming larger in size? How does the importance differ between a unicellular organism and a multicellular organism? A: For a unicellular organism, cell division means reproducing a new organism. For a multicellular organism, cell division allows for differentiation of cells and the formation of tissues. It also increases surface area.

Cell Division of Complex Eukaryotes Cell division requires:  replication of DNA,  equal distribution of DNA (division of the nucleus)  and division of the cell

The cell cycle includes the events that take place from when a new cell is formed to when that cell divides. This includes:  cell growth  replication of genetic material  correction of errors

Go to Section: includes is divided into Cell Cycle M phase (Mitosis) Interphase G 1 phaseS phaseProphaseG 2 phaseMetaphaseTelophaseAnaphase

G1: Growth of the new cell S: Replication of genetic material G2: Correction of errors Mitosis: Cell Reproduction Cytokinesis G0: Checkpoint Cell stops dividing

Mini Quiz 1. Why is the cell cycle called a cycle? 2. Why do you think that it is important for a cell to grow in size during its cell cycle? 3. What might happen to a cell if all events leading up to cell division took place as they should, but the cell did not divide? 4. What might happen if a cell skipped the checkpoints and continued to divide without stopping?