The Cell Cycle

Making new cells for growth and replacing old dying cells.

Interphase

• 95% of the cell cycle

• G1-Cell grows to mature size

• S-DNA replicates

• G2-Prepares for Cell division

• DNA is not in chromosomes yet

Interphase

Draw a picture of this phase.

Mitosis: prophase

• DNA condenses to form chromosomes (see picture)

• Nuclear membrane breaks down

Mitosis: prophase

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Centromere, chromatid, chromosome

Mitosis: metaphase

• Chromosomes line up across the center of the cell

• Each chromosome attaches to a spindle fiber at its centromere, which holds the chromatids together.

• The centrioles are at the opposite sides holding the spindle fibers.

Mitosis: metaphase

Draw a picture of this phase.

Mitosis: anaphase

• Centromeres split. The 2 chromatids separate. Each chromatid goes to the opposite end of the cell along the spindle fiber.

Mitosis: anaphase

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Mitosis: telophase

• A new nuclear membrane forms around each region of chromosomes. Cell stretches out.

Mitosis: telophase

Draw a picture of this phase.

Cytokinesis

• Cell membrane pinches. Two cells are formed with identical copies of DNA.

• DNA unwinds.

Cytokinesis

Draw a picture of this phase.

BAG CONTENTS

• Orange chromosome (4 beads, 2 centromeres, 2 chromatid)

• Blue chromosome (3 beads, 2 centromeres, 2 chromatid)

• Thread

• 2 smaller plastic bags

• 2 small white tubes (centrioles)