3.3 Cell Division and Cell Cycle

3 min read•august 28, 2024

Cell division is the cornerstone of life, growth, and reproduction. It's how we go from a single cell to a complex organism. The cell cycle, with its stages of growth and division, ensures that genetic material is accurately copied and distributed to new cells.

Mitosis and meiosis are two types of cell division with different purposes. Mitosis creates identical cells for growth and repair, while meiosis produces diverse sex cells for reproduction. Understanding these processes helps us grasp how our bodies develop, heal, and pass on genetic information.

Cell cycle stages and regulation

Interphase: Preparation for cell division

Top images from around the web for Interphase: Preparation for cell division

  • The Cell Cycle | Biology for Majors I View original

    Is this image relevant?

  • 6.2 The Cell Cycle – Concepts of Biology View original

    Is this image relevant?

  • The Cell Cycle | Biology for Majors I View original

    Is this image relevant?

1 of 3

Top images from around the web for Interphase: Preparation for cell division

  • The Cell Cycle | Biology for Majors I View original

    Is this image relevant?

  • 6.2 The Cell Cycle – Concepts of Biology View original

    Is this image relevant?

  • The Cell Cycle | Biology for Majors I View original

    Is this image relevant?

1 of 3
  • G1 phase: Cell grows in size and synthesizes proteins and RNA to prepare for DNA synthesis
    • Restriction point: Cell commits to the cell cycle and passes the G1 checkpoint
  • S phase: Cell replicates its DNA, ensuring each daughter cell will have a complete set of genetic material
    • Completion of DNA synthesis is the S checkpoint
  • G2 phase: Further cell growth and protein synthesis in preparation for mitosis
    • G2 checkpoint: Ensures all chromosomes have been accurately replicated and any DNA damage has been repaired

Mitosis and cytokinesis: Division of the nucleus and cytoplasm

  • M phase: Consists of mitosis (nuclear division) and cytokinesis (cytoplasmic division)
    • Mitosis is divided into prophase, metaphase, anaphase, and telophase
  • Cell cycle checkpoints: Critical regulatory steps that ensure the fidelity and integrity of genetic material
    • Controlled by cyclin-dependent kinases (CDKs) and their regulatory partners, the cyclins

Mitosis vs Meiosis

Similarities in mitosis and meiosis

  • Both involve duplication of genetic material, separation of chromosomes, and division of cytoplasm
  • Share some common stages (prophase, metaphase, anaphase, and telophase)

Differences between mitosis and meiosis

  • Mitosis: Produces two genetically identical daughter cells from a single parent cell
    • Essential for growth, development, and tissue repair in multicellular organisms
  • Meiosis: Produces four genetically diverse haploid gametes (sex cells) from a single diploid parent cell
    • Necessary for sexual reproduction and generates genetic variability
    • Consists of two rounds of cell division (meiosis I and meiosis II)
    • Includes additional steps such as crossing over and independent assortment

Genetic diversity in meiosis

  • Crossing over during prophase I: Exchange of genetic material between homologous chromosomes
  • Independent assortment during metaphase I: Random combination of maternal and paternal chromosomes in each gamete

Cell division for growth, repair, and reproduction

Growth and development

  • Mitosis enables a single fertilized egg to give rise to trillions of cells in an adult organism
  • Rapid cell division during embryonic development forms tissues, organs, and systems
  • Regulated cell division maintains balance between cell growth and cell death as the organism grows

Tissue repair and regeneration

  • Mitosis replaces damaged or lost cells to maintain tissue integrity and function
  • Essential for healing injuries and normal wear and tear

Asexual reproduction

  • Some organisms (plants, certain animals) use cell division for asexual reproduction
  • Vegetative reproduction or fragmentation produces new individuals without sexual reproduction

Sexual reproduction and genetic diversity

  • Meiosis generates haploid gametes (sperm and egg cells) with unique genetic combinations
  • Fusion of gametes during fertilization creates genetically diverse offspring
  • Genetic variability through meiosis and sexual reproduction is crucial for adaptability and survival of species

Abnormal cell division and health consequences

Cancer: Uncontrolled cell division

  • Disruption of cell cycle regulatory mechanisms leads to uncontrolled cell division and tumor formation
  • Mutations in tumor suppressor genes (p53) or proto-oncogenes (Ras) can cause cancer development
  • Mutations can be inherited or acquired through environmental factors (radiation, carcinogens)

Chromosomal abnormalities

  • Aneuploidy: Abnormal number of chromosomes due to errors in chromosome segregation during mitosis or meiosis
    • Examples: Down syndrome (trisomy 21), Turner syndrome (monosomy X)
  • Chromosomal instability syndromes (Bloom syndrome, Fanconi anemia): Defects in DNA repair mechanisms leading to increased chromosomal breakage and rearrangements
    • Predispose individuals to various cancers

Reproductive disorders

  • Abnormalities in meiosis can result in infertility or genetic disorders in offspring
  • Nondisjunction during meiosis leads to aneuploid gametes, causing miscarriages or chromosomal disorders if fertilization occurs

Autoimmune disorders

  • Uncontrolled cell division can contribute to the development of autoimmune disorders
  • Immune system mistakenly attacks body's own tissues, causing chronic inflammation and tissue damage
© 2024 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.
Back
Glossary
Glossary
Next guide