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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.