Cell Cycle and Mitosis Introduction How do little

Introduction: How do little elephants grow up to be BIG elephants?

Three reasons why cells duplicate 1. Growth 2. Repair 3. Replacement

DNA Replication Cell Duplication - In order for cells to duplicate, the DNA needs

B. Cell Cycle • The cell cycle has three stages I. Interphase II. Mitosis

I. Interphase occurs before mitosis begins Longest stage in the cell cycle (95% of

II. Mitosis The shortest stage • Allows for division of genetic material • There

Prophase 1 st step in Mitosis • DNA that has replicated coils up into

Prophase 1 st step in Mitosis Nucleolus disappears Centrioles (or poles) appear and begin

Metaphase 2 nd step in Mitosis • Spindle fibres pull the chromosomes into a

Anaphase 3 rd step in Mitosis Spindle fibres contract and shorten which pulls the

Telophase 4 th step in Mitosis One complete set of chromosomes is now at

III. Cytokinesis occurs after Mitosis Divides the cytoplasm and organelles into two identical daughter

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

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Cell Cycle and Mitosis

Introduction: How do little elephants grow up to be BIG elephants?

Three reasons why cells duplicate 1. Growth 2. Repair 3. Replacement

DNA Replication Cell Duplication - In order for cells to duplicate, the DNA needs to first replicate

B. Cell Cycle • The cell cycle has three stages I. Interphase II. Mitosis III. Cytokinesis

I. Interphase occurs before mitosis begins Longest stage in the cell cycle (95% of the cell’s life) • Cell grows, DNA is replicated(# doubles) and prepared for division • Some organelles begin to duplicate • Nucleus Cell membrane Cytoplasm

Interphase Animal Cell

II. Mitosis The shortest stage • Allows for division of genetic material • There are four phases •

Prophase 1 st step in Mitosis • DNA that has replicated coils up into denselypacked chromosomes

Prophase 1 st step in Mitosis Nucleolus disappears Centrioles (or poles) appear and begin to move to opposite end of the cell • Spindle fibers form between the poles • Chromosomes attach to the spindle fibres via their centromere • • Centrioles Spindle fibers Chromosomes

Prophase 1 st step in Mitosis

Prophase Animal Cell Spindle fibers

Metaphase 2 nd step in Mitosis • Spindle fibres pull the chromosomes into a single line across the middle of the cell Centrioles Spindle fibers

Metaphase Animal Cell

Anaphase 3 rd step in Mitosis Spindle fibres contract and shorten which pulls the chromosomes apart • Sister chromatids move to opposite ends of the cell • Centrioles Spindle fibers

Anaphase Animal Cell

Telophase 4 th step in Mitosis One complete set of chromosomes is now at each pole • Spindle fibres disappear • Nuclear membrane forms around chromosomes • Nuclear membrane Chromosomes

Telophase Animal Cell

III. Cytokinesis occurs after Mitosis Divides the cytoplasm and organelles into two identical daughter cells by pinching inwards at the centre of the cell • Each nucleus has identical genetic material •

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Cytokinesis