The Cell Life Cycle Learning Objectives Describe the

The Cell Life Cycle

Learning Objectives • Describe the cell life cycle. • Understand the role of cell division in the cell cycle. • Understand the process of terminal differentiation in cells • Describe mitosis and cellular differentiation. • Describe meiosis and contrast it with mitosis.

Cell division • Cell division is the reproduction of cells • Apoptosis is the genetically controlled death of cells • Mitosis is the nuclear division of somatic cells • Meiosis produces sex cells

Interphase • Most somatic cells spend the majority of their lives in this phase • Interphase includes – G 1 –S – G 2

The Cell Life Cycle

DNA Replication

Mitosis, or nuclear division, has four phases • • Prophase Metaphase Anaphase Telophase During cytokinesis, the cytoplasm divides and cell division ends

Interphase, Mitosis, and Cytokinesis

Interphase, Mitosis, and Cytokinesis

Mitotic rate and cancer • Generally, the longer the life expectancy of the cell, the slower the mitotic rate – Stem cells undergo frequent mitoses – Growth factors can stimulate cell division – Abnormal cell division produces tumors or neoplasms • Benign • Malignant (invasive, and cancerous) – Spread via metastasis – Oncogenes

Chromosomes in Mitosis and Meiosis Figure 28. 6

Differentiation • • • Process of specialization Results from inactivation of particular genes Produces populations of cells with limited capabilities • Differentiated cells form tissues

You should now be familiar with: • • The cell life cycle. Mitosis and cellular differentiation. Terminal differentiation and the Go phase. Meiosis and cell ploidy.