Comparison of Mitosis and Meiosis

Similar Vocabulary in Biology

  • Important to note terms: Chromosome, chromatid, chromatin, transcription, translation, mitosis, meiosis.

Overview of Mitosis and Meiosis

  • Both processes are involved in cell division and result in new cells.

  • Mitosis produces body cells.

  • Meiosis produces gametes (sperm and egg cells).

  • Starting cell for both processes is diploid (2N) with 46 chromosomes total (23 from mom and 23 from dad).

Interphase

  • Occurs before mitosis and meiosis.

  • Cell duplicates chromosomes, resulting in 92 chromatids (still counted as 46 chromosomes as they are attached at the centromere).

  • Interphase is crucial as chromosomes are duplicated before actual division begins.

  • Simplified visualization uses 6 chromosomes (easier to draw).

  • Fun fact: Some insects, like mosquitoes, also undergo mitosis and meiosis.

PMAT Stages

  • Both mitosis and meiosis utilize the acronym PMAT (Prophase, Metaphase, Anaphase, Telophase).

  • Meiosis goes through these stages twice, hence the stages have numbers: I for the first round and II for the second round.

Prophase

  • Mitosis Prophase: Chromosomes condense and become visible.

  • Meiosis Prophase I: Chromosomes pair with homologous counterparts for crossing over, transferring genetic information. Homologous chromosomes contain the same genes, one from each parent.

Metaphase

  • Mitosis Metaphase: Chromosomes align in the middle of the cell in a single file line.

    • Remember: M for middle.

  • Meiosis Metaphase I: Homologous pairs align in the middle, not in a single line.

Anaphase

  • Mitosis Anaphase: Chromatids are pulled apart to opposite sides of the cell.

    • Remember: A for away.

  • Meiosis Anaphase I: Homologous chromosomes (not chromatids) are pulled apart to opposite sides.

Telophase and Cytokinesis

  • Mitosis Telophase: New nuclei are forming around separated chromosomes, leading to two new cells.

  • Meiosis Telophase I: Similar to mitosis but involves homologous chromosomes.

    • After cytokinesis, two diploid cells remain, each with 46 chromosomes (in humans).

Meiosis II

  • Prophase II: Chromosomes condense, less eventful without homologous pairing.

  • Metaphase II: Chromosomes line up in single file (like mitosis).

  • Anaphase II: Chromatids are separated and pulled away.

  • Telophase II: New nuclei form, followed by cytokinesis.

  • Results in four non-identical haploid cells (gametes), each with 23 chromosomes in humans.

Fertilization and Development

  • When sperm and egg gametes combine, they form a diploid fertilized egg (zygote) with 46 chromosomes.

  • The zygote will undergo mitosis to develop into a new organism.

Conclusion

  • Encouragement to stay curious about biological processes.

Feature

Mitosis

Meiosis

Purpose

Produces body cells

Produces gametes (sperm and egg cells)

Starting Cell

Diploid (2N), 46 chromosomes (23 from each parent)

Diploid (2N), 46 chromosomes (23 from each parent)

Number of Divisions

One division

Two divisions (Meiosis I and Meiosis II)

Chromosome Duplication

Occurs during interphase prior to division

Occurs during interphase prior to division

Chromosome Line-Up

Single file line during metaphase

Homologous pairs line up in the middle during metaphase I

Type of Cell Produced

Two identical diploid cells

Four non-identical haploid cells (gametes)

Genetic Variation

No crossing over; genetic material is identical

Crossing over occurs during prophase I

Anaphase Separation

Sister chromatids separated

Homologous chromosomes separated in Anaphase I