The Cell Life CycleThe Cell Life Cycle

Learning ObjectivesLearning Objectives

• Describe the cell life cycle.Describe the cell life cycle.

• Understand the role of cell division in the cell Understand the role of cell division in the cell cycle.cycle.

• Understand the process of terminal differentiation Understand the process of terminal differentiation in cellsin cells

• Describe mitosis and cellular differentiation.Describe mitosis and cellular differentiation.

• Describe meiosis and contrast it with mitosis.Describe meiosis and contrast it with mitosis.

• Cell division is the reproduction of Cell division is the reproduction of cellscells

• Apoptosis is the genetically controlled Apoptosis is the genetically controlled death of cellsdeath of cells

• Mitosis is the nuclear division of Mitosis is the nuclear division of somatic cellssomatic cells

• Meiosis produces sex cellsMeiosis produces sex cells

Cell divisionCell division

• Most somatic cells spend the majority of their Most somatic cells spend the majority of their lives in this phaselives in this phase

• Interphase includesInterphase includes– G1G1– S S – G2G2

InterphaseInterphase

The Cell Life CycleThe Cell Life Cycle

DNA ReplicationDNA Replication

• ProphaseProphase

• MetaphaseMetaphase

• AnaphaseAnaphase

• TelophaseTelophase

Mitosis, or nuclear division, has Mitosis, or nuclear division, has four phasesfour phases

During cytokinesis, the cytoplasm divides and cell During cytokinesis, the cytoplasm divides and cell division endsdivision ends

Interphase, Mitosis, and CytokinesisInterphase, Mitosis, and Cytokinesis

Interphase, Mitosis, and CytokinesisInterphase, Mitosis, and Cytokinesis

• Generally, the longer the life expectancy of the Generally, the longer the life expectancy of the cell, the slower the mitotic ratecell, the slower the mitotic rate– Stem cells undergo frequent mitoses Stem cells undergo frequent mitoses – Growth factors can stimulate cell divisionGrowth factors can stimulate cell division– Abnormal cell division produces tumors or neoplasmsAbnormal cell division produces tumors or neoplasms

• BenignBenign

• Malignant (invasive, and cancerous)Malignant (invasive, and cancerous)– Spread via metastasisSpread via metastasis

– OncogenesOncogenes

Mitotic rate and cancerMitotic rate and cancer

Figure 28.6

Chromosomes in Mitosis and MeiosisChromosomes in Mitosis and Meiosis

• Process of specializationProcess of specialization

• Results from inactivation of particular genesResults from inactivation of particular genes

• Produces populations of cells with limited Produces populations of cells with limited capabilitiescapabilities

• Differentiated cells form tissuesDifferentiated cells form tissues

DifferentiationDifferentiation

• The cell life cycle.The cell life cycle.

• Mitosis and cellular differentiation.Mitosis and cellular differentiation.

• Terminal differentiation and the GTerminal differentiation and the Goo phase. phase.

• Meiosis and cell ploidy.Meiosis and cell ploidy.

You should now be familiar with:You should now be familiar with: