Do now!! What two (2) reasons do you think cells divide?

Ch. 10 Cell Growth and Reproduction Why do cells divide?

Body Growth and Repair All living things grow All living things grow All living things need to repair themselves when injured All living things need to repair themselves when injured New cells are made to make these two things happen New cells are made to make these two things happen The process of making new cells is called The process of making new cells is called MITOSIS MITOSIS

Cell Cycle The life of a cell is called the cell cycle The life of a cell is called the cell cycle It has five main phases It has five main phases –G 1 : this phase is for GROWTH and making new organelles. organelles. –S phase: this phase for SYNTHESIZING chromosomes. chromosomes. –G 2 : this phase is a second GROWTH phase dedicated to growing in size to prepare for cell division. to growing in size to prepare for cell division. –Mitosis: process of cell division –Cytokinesis: the end process of one cell becoming two cells two cells

Mitosis Done in all the body cells of living things Done in all the body cells of living things Makes a copy of original cell Makes a copy of original cell Done in four steps Done in four steps –Prophase –Metaphase –Anaphase –Telophase

Prophase 1. Sister chromatids begin to shorten and thicken into chromosomes 2. Nuclear membrane begins to break down 3. Centrioles move to the poles of the cell 4. Spindle fibers form from each Centriole towards the center of the cell

Metaphase 1. Centrioles are at opposite side of the cell the cell 2. Chromosomes line up in the middle of the cell 3. Spindle fibers attach to the centromere of the chromosome

Anaphase 1. Chromosomes are pulled apart 2. Spindle fibers disintegrate after chromosome passes 3. Chromosomes are pulled towards the centrioles

Telophase 1. Each side of the cell has a complete set of chromosomes 2. The cell starts to pinch in to split 3. Nucleus starts to reappear

4.

CYTOKINESIS At the very end of mitosis cytokinesis occurs At the very end of mitosis cytokinesis occurs “Cyto”- meaning cell “Cyto”- meaning cell -”kinesis” process of making new -”kinesis” process of making new

Correctly identify the following phases of the cell cycle. Each number on the following picture represents a phase of the cell cycle Each number on the following picture represents a phase of the cell cycle in you do now for the week place the correct name of the phase for each number. in you do now for the week place the correct name of the phase for each number.