Chapter 8.1 Cell Division and Reproduction

Why do cells go through cell division? To grow –Organisms grow by ADDING more cells To replace dead cells –All cells will die so they need to be replaced To replace damaged cells –Cells will be damaged by injury (cut)

Definition of Cell Division Cell division is the process of one cell dividing into two identical daughter cells

DNA - Hereditary Material DNA is stored in a eukaryotic cells nucleus –Plant cells –Animal cells

What is Chromatin? Loose (stringy) DNA in a cells nucleus is called chromatin DNA before cell division DNA ‘hanging out’

Chromosome doubles Chromatin condenses (shrinks up) and doubles just before cell division –This forms a chromosome (X). X

What is a Chromosome? A chromosome is a structure made up of DNA and protein in the nucleus of a eukaryotic cell

Cell Cycle The cell cycle is the period of time from the beginning of one cell division to the beginning of the next. The cell cycle has 3 parts: –InterphaseSee cycle on page 155 –Mitosis –Cytokinesis

1. Interphase First part of the cell cycle Time in between cell divisions –Cell is on vacation Longest phase. Most time is spent in interphase At end, chromatin (stringy) doubles into a chromosome (X)

Mitosis Second part of the cell cycle Makes 2 new identical nuclei Has 4 steps: –Prophase –Metaphase –Anaphase –Telophase

2. Prophase First step of mitosis Chromatin in nucleus coils into chromosomes (X’s) Nuclear membrane begins to disappear

3. Metaphase Second step of mitosis Chromosomes line up in the middle of the cell Spindle fibers attach to the chromosomes

4. Anaphase Third step of mitosis Chromosomes separate and begin to move to opposite ends of the cell

5. Telophase Final step of mitosis Two new nuclei form around the separated chromosomes Chromosomes unwind to form chromatin Mitosis ends

6. Cytokinesis Final part of the cell cycle Makes 2 new identical daughter cells Shortest phase END of the cell cycle

Cell Cycle Interphase Prophase MetaphaseMitosis Anaphase Telophase Cytokinesis

Cell Cycle Mnemonic Write a mnemonic for cell division (Ex. King Henry Died By Drinking Chocolate Milk.) I P MAdd a COLORED Apicture T C

Cell Cycle Mnemonic I Played Music At The Concert