Cellular Structure and Function pt. 2

Prophase

• Chromatin condenses into 2 chromosomes

• Mitotic spindle begins to form

Metaphase

• Nuclear membrane disintegrates

• Sister chromatids align along metaphase plate with aid of spindle fibers attached to the kinetochore of the centromeric region

Anaphase

• Spindle fibers pull sister chromatids in opposite directions towards the poles of the cell

• Centromere regions separate

Telophase

• Two nuclear envelopes form around separated chromosomes at opposite ends

• Complete division of genetic material

Cytokinesis

Division of all other organelles of the cell to complete mitosis

Interphase

Composed of G1, S, and G2

G1 (First gap)

• Cell growth

• Protein synthesis

S (synthesis)

• Cell stops growing

• Synthesizes and replicates DNA

G2 (Second gap)

• Cell growth

• Protein synthesis

• Organelle development

Multicellular organisms

• Cell division allows organism to grow and develop

• When growth is complete, cell division is necessary for repair and renewal

Unicellular organisms

Can reproduce/clone offspring through cell division

G1/S checkpoint

Cell cycle stops and cell won’t divide anymore

G2/M checkpoint

Cell cycle stops to repair damaged DNA

G0 (senescence)

Cell stops dividing and ‘retires’ until apoptosis

Apoptosis

Programmed cell death brought by formation of ‘suicide’ proteins

Chromatin

The DNA-protein complex packed into the nucleus during interphase

Chromosomes

Chromatin condenses into chromosomes when cell enters mitotic phase

Chromatids

Each chromosome formed from chromatin during prophase has two sister chromatids

Cancer

• Abnormal cells dividing without control of normal cellular checks and balances

• Cancerous cells have the ability to invade other tissues (metastasis) and consume their resources

When mitosis and apoptosis are not in homeostasis…

Tumors can form