Cell Cycle Overview

The Cell Cycle

  • Cell Division

    • Essential for single-celled organisms and multicellular eukaryotes.

    • Roles include asexual reproduction, growth, development, and tissue renewal.

  • Cell Cycle Phases

    • Interphase: Growth, DNA replication, preparation for division.

    • Subdivided into G₁, S, and G₂ phases.

    • Mitosis: Division of genetic material.

    • Stages: prophase, prometaphase, metaphase, anaphase, telophase.

    • Cytokinesis: Division of cytoplasm, results in two daughter cells.

  • Chromosomal Structure

    • Eukaryotic DNA organized into chromosomes consisting of chromatin.

    • Gametes have half the chromosomes compared to somatic cells.

    • Sister chromatids connected at centromeres, separate during anaphase.

  • Mitotic Spindle

    • Composed of microtubules to control chromosome movement.

    • Centrioles replicate during interphase and migrate during cell division.

  • Cell Cycle Control System

    • Directed by signaling molecules with specific checkpoints.

    • Cyclins and cyclin-dependent kinases (Cdks) regulate progression through the cell cycle.

    • MPF (maturation-promoting factor) triggers the M phase.

  • Checkpoints

    • G₁, G₂, and M checkpoints assess cell condition and readiness for division.

    • Abnormal signals can lead to exit into G0 phase (non-dividing state).

  • External Influences on Cell Division

    • Growth factors stimulate cell division.

    • Density-dependent inhibition prevents overcrowding; anchorage dependence required to divide.

  • Cancer Cells

    • Exhibit uncontrolled growth; do not follow density-dependent or anchorage-dependent regulations.

    • Treated with chemotherapeutic drugs that affect the cell cycle, potentially targeting fast-dividing normal cells as well.

The Cell Cycle - Cell Division - Essential for single-celled organisms and multicellular eukaryotes. - Roles include asexual reproduction, growth, development, and tissue renewal. - Cell Cycle Phases - Interphase: Growth, DNA replication, preparation for division. - Subdivided into G₁, S, and G₂ phases. - In the G₁ phase ("first gap"), the cell grows, synthesizes proteins, and produces new organelles. - In the S phase ("synthesis"), the cell continues to grow as it synthesizes new DNA, replicating its chromosomes. - In the G₂ phase ("second gap"), the cell continues to grow, synthesizes proteins, and prepares for mitosis; it also checks the duplicated chromosomes for errors. - Mitosis: Division of genetic material. - Stages: prophase, prometaphase, metaphase, anaphase, telophase. - Cytokinesis: Division of cytoplasm, results in two daughter cells. - Chromosomal Structure - Eukaryotic DNA organized into chromosomes consisting of chromatin. - Gametes have half the chromosomes compared to somatic cells. - Sister chromatids connected at centromeres, separate during anaphase. - Mitotic Spindle - Composed of microtubules to control chromosome movement. - Centrioles replicate during interphase and migrate during cell division. - Cell Cycle Control System - Directed by signaling molecules with specific checkpoints. - Cyclins and cyclin-dependent kinases (Cdks) regulate progression through the cell cycle. - MPF (maturation-promoting factor) triggers the M phase. - Checkpoints - G₁, G₂, and M checkpoints assess cell condition and readiness for division. - Abnormal signals can lead to exit into G0 phase (non-dividing state). - External Influences on Cell Division - Growth factors stimulate cell division. - Density-dependent inhibition prevents overcrowding; anchorage dependence required to divide. - Cancer Cells - Exhibit uncontrolled growth; do not follow density-dependent or anchorage-dependent regulations. - Treated with chemotherapeutic drugs that affect the cell cycle, potentially targeting fast-dividing normal cells as well.