Cell Cycle Cell Growth and Division Animal Cell

Cell Cycle : Cell Growth and Division Animal Cell Mitosis II

Mitosis

The functions of cell division: Reproduction

The functions of cell division: Growth and development

The functions of cell division: Tissue renewal

Eukaryotic chomosomes

Chromosome duplication and distribution during mitosis Chromosome Coiling video DNA coiled around histone proteins and condensed into a chromosome

The cell cycle

The stages of mitotic cell division in an animal cell: G 2 phase; prometaphase

The stages of mitotic cell division in an animal cell: metaphase; anaphase; telophase and cytokinesis. APC : anaphse promoting complex kinetochores

The mitotic spindle at metaphase

Cytokinesis in animal and plant cells video plant cytokinesis video

Mitosis

Mitosis in a plant cell

Mitosis in an onion root

Bacterial cell division (binary fission) (Layer 1)

Bacterial cell division (binary fission) (Layer 2)

Bacterial cell division (binary fission) (Layer 3)

A hypothesis for the evolution of mitosis

Chromosome migration during anaphase

Evidence for cytoplasmic chemical signals in cell cycle regulation

Mechanical analogy for the cell cycle control system Cdks – cyclin dependant kinase signals/ concentration dependant Cyclin – Fluctuates throughout/ controlling activity of MPF – maturation promoting factor? Phosphorylates kinases that sets off enzymes involved in: digestion of nuclear envelope, chromosome condensation, spindle formation MPF triggers Adult stem cell holding pattern

Molecular control of the cell cycle at the G 2 checkpoint Cdk MPF also initiates enzyme for MPF breakdown

MPF Multiple targets, signal amplification, produces a transcription factor that signals a enzyme produced to digest the MPF…. eventually turning of the total signal. Mitosis

Internal Signals Checkpoint Control System for Mitosis G 1 – Restriction Point…. . reached…. . go to S…G 2…M Go-ahead signal received GO – Restriction Point…. . Not reached…. . go to GO Nondividing state G 2 End – cyclin high conc. MPF formed, triggers M M – MPF triggers destruction enzymes for MPF, ends mitosis. (Maturation Promoting Factor)

Maturation Promoting Factor • Assembled during G 2 = cyclin + cdks • Causes nuclear fragmentation • Phosphorylates protein kinases…. leading to mitosis …… leading to destruction of MPF Skin cells: repeatedly divide Liver cells: divide in response to injury Muscle cells: stay in Go until death, stimulated by PDGF, chemical signal to divide from fibroblasts to produce new cells after injury to site. Nerve cells: reach maturity then stop, new research has found adult stem cells that can produce new cells.

The effect of a platelet derived growth factor on cell division PDGF External Signals Growth factors = mitogen

Fibroblast growth: connective tissue cells

Density-dependent inhibition of cell division

The growth and metastasis of a malignant breast tumor

Breast cancer cell

Mammogram: normal (left) and cancerous (right)

From Mitosis to Meiosis • Video: Cell Cycle to Fertilization