Cell Division The Cell Cycle

Reviewing the Chromosome… Each chromosome (coiled DNA) consists of two identical “sister” chromatids. Each pair of chromatids are attached at an area called the centromere. Sister chromatids Centromere

Cell Cycle The cell cycle is the series of events that cells go through as they grow and divide.

Cell Cycle Interphase is the period of rest and growth that occurs between cell divisions.

Your Turn! Based on the image, what does a cell spend most of its time doing?

The characteristics of Interphase… G1 Phase: The cell grows S Phase: The DNA of the cell is copied into 2 sets (DNA replication) G2 Phase: The cell finishes growing and gets ready for mitosis!

Cell Cycle Cell Division: Mitosis – the division of the nucleus that results in two genetically identical cells Cytokinesis – the division of the cytoplasm

Your Turn! What is the purpose of mitosis?

Mitosis

PROPHASE Things to remember… it is the start of mitosis Spindle fibers Things to remember… it is the start of mitosis the nucleus breaks down the chromosomes form Centrioles Nuclear membrane Chromosomes (paired chromatids)

METAPHASE Things to remember… the chromosomes line up across the middle of the cell the spindle fibers attach at the centromeres

ANAPHASE Things to remember… the chromatids are pulled away from each other

TELOPHASE Things to remember… two nuclei start to reform cytokinesis starts

Your Turn! What do you think each cell would look like if this did occur? Why?

CELL DIVISION AT THE CONCLUSION OF CELL DIVISION EACH OFFSPRING WILL RECEIVE IDENTICAL COPIES OF THE CELL’S CHROMOSOMES.

Your Turn! How many chromosomes are in a human skin cell before mitosis? After?