1. From a cell to an organism Chapter 3 lesson 1 Life Science Presented by Mrs. Waterbury Paramecium

2. Section 3-1 Cell Cycle and Cell Division Length of cell cycle depends on the cell skin – 15-20 days nerve – 50-60 yrs Growth = cell number increases Division development Ex. Red blood cells – 2 to 3 billion per second

3. Interphase – Cell Cycle phase 1 (9/10 of life) 1) rapid growth and replication of organelles; cellular functions –ex making protein; stomach cells making enzymes G1 (some cells stop here ex brain cells) 2) Growth & DNA replication S chromatin (what chromosomes are called during interphase) doubling; sister chromatids held together by a centromere make up 1 duplicated chromosome see pg 88 pict 3) preparation for division; store energy; growth; organelle replication G2

4. 4) Mitosis cell cycle phase 2 (cell division (nuclear division) stage1 ) (1/10) (average time – 24 hrs) Interphase looks like spaghetti STAGES: 1) Prophase Chromosomes visible by coiling together tightly Nuclear membrane breaks down Nucleolus disappears Centrioles (animals only) move to opp. Ends Spindle Fibers begin to stretch across PROPHASE INTERPHASE

5. 2) Metaphase Chromosomes line up in the center pushed by the fibers Attach to a fiber by the centromere Shortest phase

6. 3) Anaphase Centromere divide these are the structures that hold the double stranded chromosome together Chromosomes (sister chromatids) separate Strands start to move toward opposite ends Cell begins to lengthen centromere

7. 4) Telophase Nuclear membrane forms around each mass of chromosomes Two new identical nuclei are formed New nucleolus appears Animals – cytoplasm divides (cytokinesis – cell division stage 2) forms a furrow Plants – cell plate forms (cytokinesis) Why? A new cell has formed that is identical to the parent cell (daughter cells Will have the same number of chromosomes! http://www.bioweb.uncc.edu/biol1 110/Stages.htm http://www.unomaha.edu/~swick/ 2740mitosis.html

8. Results of cell division How some unicellular organisms reproduce (paramecium) Growth Replacement – worn out or damaged ex skin Repair – broken bones, cuts (not all can be repaired – ex nerves