Life of a Cell The Cell Cycle

The Cell Cycle Consists of: Interphase Mitosis Cytokinesis

Interphase NOT a “resting” phase for the cell. The cell carries out metabolic processes and prepares for cell division during interphase. G1: Cell growth S: DNA is replicated (46 chromosomes in humans) G2: Cell growth

Interphase (Plant)

Interphase (Animal) Cell membrane Nuclear membrane

Mitosis Process that divides the nucleus of a cell Purpose is to create two daughter cells with identical information Growth and development and/or repair of tissue Each daughter cell receives the exact same # and type of chromosomes Consists of 4 phases: Prophase Metaphase Anaphase Telophase

Prophase Illustration In prophase: Nuclear membrane disintegrates (disappears) Chromatin coils into chromosomes and becomes visible Chromosomes consist of 2 chromatids Centrosomes migrate to opposite sides of cell; spindle fibers form and attach to chromosomes Centrosomes

Prophase (Plant) Chromatin is condensing into chromosomes

Prophase (Animal) Chromosomes

Metaphase Illustration Centromere Centriole *Chromosomes still consist of two chromatids

Metaphase (Plant)

Metaphase (Animal)

Anaphase Illustration In Anaphase: Chromatids separate at the centromere, becoming individual chromosomes Chromosome now = 1 chromatid Spindle fibers shorten, pulling chromatids to opposite poles of cell Centriole Spindle Fibers Chromatid Centromere

Anaphase (Plant) Chromatids

Anaphase (Animal) Chromatid Centriole

Telophase Illustration In telophase: Nuclear membrane forms again Chromosomes uncoil into long strands of chromatin Cytokinesis begins

Telophase (Plant) Nuclear membrane forming Chromatin

Telophase (Animal) Nucleus

Cytokinesis Illustration In cytokinesis: The cytoplasm divides between the daughter cells Happens by cleavage furrow (animal) or formation of cell plate (plant) Produces 2 daughter cells Cleavage furrow

Cytokinesis (Plant)

Cytokinesis (Animal) Cleavage Furrow