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Honors Biology - Cell Cycle - Unit 5 Review

Key Phases of Cell Cycle

  • Interphase: Phase when the cell is not dividing but performing its normal functions. Includes:

    • G₁ Phase: The first stage of cell growth and development after mitosis.

    • S Phase: The stage where DNA replication occurs (single-stranded chromosomes become double-stranded).

    • G₂ Phase: The second stage where the cell continues to grow and develop before division.

Mitosis Stages

  • Mitosis: The process of cell division resulting in two identical daughter cells.

    • Prophase: Nuclear membrane disappears; chromosomes appear.

    • Metaphase: Chromosomes line up at the middle of the cell.

    • Anaphase: Chromosomes separate into sister chromatids.

    • Telophase: Two new nuclei form.

  • Cytokinesis: The division of the cytoplasm, resulting in two distinct cells.

Important Concepts

  • Cancer: A disease caused by uncontrolled mitotic cell division that leads to tumor formation.

  • Tumor: A mass of cells resulting from excessive mitotic activity.

  • Carcinogen: A substance that promotes the formation of cancer.

  • Purpose of mitotic division: To divide one somatic cell into two identical daughter cells.

Types of Reproduction Related to Mitosis

  • Asexual Reproduction: Depends on mitotic division, leading to genetically identical offspring.

  • Possible answers for cell division types include: Asexual reproduction and viral reproduction.

  • Tissue growth is indicated by the presence of significant mitosis under a microscope.

Meiosis

  • Meiosis: A type of reproduction that reduces the chromosome number by half, producing gametes (sperm and egg).

    • Diploid: Cells with two sets of chromosomes (e.g., somatic cells).

    • Haploid: Cells with one set of chromosomes (e.g., gametes).

  • Fertilization: The joining of an egg and a sperm to form a zygote, which becomes an embryo.

  • Crossing Over: The process during meiosis where homologous chromosomes exchange genetic material, providing genetic variation.

Key Terms in Meiosis

  • Gamete: Sex cells (sperm and egg).

  • Zygote: The single cell formed after fertilization.

  • Variations: Genetic differences due to sexual reproduction.

  • Homologous chromosomes: Pairs of chromosomes from each parent.

Viruses vs. Bacteria

  • Bacteria: Living prokaryotic cells that reproduce via binary fission (asexual reproduction).

  • Viruses: Nonliving pathogens that require a host cell to reproduce, using either the lysogenic or lytic cycle.

    • Capsid: The protein shell of a virus.

    • Nucleic Acid: The genetic material of a virus (can be DNA or RNA).

Reproduction and Cell Formation

  • Mitosis:

    • Produces two identical daughter cells.

    • Used for growth and tissue repair (new skin cells, etc.).

    • Maintains the same chromosome number as original cells.

  • Meiosis:

    • Produces four unique haploid cells (gametes).

    • Crucial for sexual reproduction, mixing DNA from two parents.

Meiosis Questions Summary

  • Purpose of meiosis is to produce gametes (egg and sperm).

  • Diploid cells have two sets of chromosomes; haploid cells have one set.

  • Gametes produced by meiosis are sex cells, while body cells are diploid.