Cell Cycle and Mitosis!

Review Why do cells divide??

Big cells are inefficient! Nutrients can’t reach the organelles!

Proteins can’t be synthesized quickly enough! Volume increases much

faster than surface area!

Before Cells Divide…

• INTERPHASE!–Cells carry out normal functions–Most of a cell’s time is spent in this phase–3 parts! G1, S, and G2

G1 PHASE

• DNA stored as chromatin loose and unwound

• Cell grows and organelles replicate

SPHASE

• Synthesis• DNA replicates

G2PHAS

E• Rapid growth before division

INTERPHASE

Now the cell is ready to divide!

• MITOSIS: The division of the nucleus!• 4 Phases!

PROPHASE• DNA condenses into chromosomes• Nucleus disappears • Spindle fibers form• Centrioles move to side

PROPHASE:

METAPHASE• Chromosomes line up down the middle of the

cell• Spindle fibers attach to centromere

METAPHASE

ANAPHASE• Chromatids separate • Spindle fibers pull chromosomes to the sides

ANAPHASE

TELOPHASE• Cleavage Furrow forms• Nucleus reforms• DNA unravels • Centrioles and spindle fibers disappear

TELOPHASE

Quick Mitosis Summary…

• Mitosis Division of the nucleus– 1 Prophase– 2 Metaphase– 3 Anaphase– 4 Telophase

– Ready for the last part of the cell cycle???

CYTOKINESIS!• Division of the cytoplasm• Cell splits into 2 new cells!• NOT a part of mitosis

Cell PlateCleavage Furrow

The Cell Cycle!

The Cell Cycle:

The Cell Cycle: