1. Chapter 10 Section 2

2.  The cell cycle is a repeating sequence of cellular growth and division during the life of a cell.  The life of a eukaryotic cell cycles through phases of growth, DNA replication, preparation for cell division, and division of the nucleus and cytoplasm.  The cell cycle is made up of five phases. The first three phases together are known as interphase. The remaining two phases make up cell division (mitosis).

3. Page 228 in Text Book

4.  Interphase: 1 st phase of the cell cycle where the cell is not dividing but is growing and preparing to divide  The “Prep” Phase  Consists of 2 Gap Phases and Synthesis Phase  Skin cells: spend less time in interphase ▪ Why?: they divide often  Nerve cells: spend more time in interphase ▪ Why?: they divide seldom

5.  During the G1 phase cells grow rapidly as the cell builds more organelles  G1 occupies a major portion of the cell’s life  Checkpoint:  Cell checks surroundings before it copies DNA  If favorable conditions and cell is healthy/large enough it will enter synthesis phase

6.  During the S Phase, the cell’s DNA is copied  At the end of the phase, the cell’s nucleus has 2x as much DNA  Each chromosome consists of 2 identical chromatids that are attached to a centromere

7.  During G2 the cell continues to grow and divide  Microtubules (hollow protein fibers) are formed and organized in cytoplasm  Checkpoint:  Check for any mistakes in copied DNA  Enzymes correct mistakes that are found  Ensures DNA of daughter cells will be identical to DNA of original cell  Proteins double-check that cell is large enough to divide  If pass may begin to divide=mitosis