The Cell Cycle

Cell Size

Surface Area (length x width x 6)

Volume (length x width x height)

Ratio of Surface Area to Volume

Why Divide?

A higher surface area/volume allows the cell to move materials in and out more efficientlySmaller cells have higher SA/Vol. ratios

10-2 Cell Cycle

G1 Phase

S Phase

G2 Phase

M Phase

Interphase – G1- cell grows, normal

functions of life– S Phase – DNA

replicates

– G2- cell grows and prepares for mitosis

M Phase – Mitosis– Cell division

Chromosomes

In Interphase, chromosomes appear as chromatin

When mitosis begins, chromatin condenses to form visible chromosomesSister chromatids are identical halves of a duplicated chromosome• Chromatids are joined at the

centromere

Mitosis - Prophase

Chromosomes condenseNuclear membrane disappearsSpindle fibers form as centrioles move toward poles

Mitosis - Metaphase

Chromosomes line up along the cell’s center Chromosomes attach to spindle fibers at the centromeres

Mitosis - Anaphase

Sister chromatids separate and move toward poles

Mitosis – Telophase and Cytokinesis

Telophase – last step of mitosis– Individual chromosomes gather

at poles– Nuclear membrane reforms

Cytokinesis – follows telophase– Cell pinches in half– Two cells form

• Animal Cells – cleavage furrow• Plant Cells – cell plate

Mitosis in Plant vs. Animal Cells

Plant Cells Animal Cells

SpindleFibers

Stages of mitosis (PMAT)

No centrioles

Cell plate forms

between cells

Cell pinches at cleavage

furrow

Centrioles

Another Look at Mitosis

Onion Cells

Mitosis in a Lily Cell

Mitosis in Whitefish Cells

Mitosis Review

How many chromosomes did this cell start with?– FOUR

During which phase are sister chromatids separated?– ANAPHASE

How many chromosomes are in EACH daughter cell?– FOUR