Chapter 8.1 Cell Division and Reproduction. Why do cells go through cell division? To grow...
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Transcript of Chapter 8.1 Cell Division and Reproduction. Why do cells go through cell division? To grow...
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 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:– Interphase See 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
• Metaphase Mitosis
• Anaphase
• Telophase
• Cytokinesis
Cell Cycle Mnemonic• Write a mnemonic for cell division• (Ex. King Henry Died By Drinking
Chocolate Milk.)• I• P• M Add a COLORED • A picture• T• C
Cell Cycle Mnemonic
• I
• Played
• Music
• At
• The
• Concert