Mitosis Overview

Mitosis

• Mitosis is a form of asexual reproduction where a parent cell divides to create two identical daughter cells.

• The result is two genetically identical daughter cells.

• The purpose is for repair and growth; in single-celled organisms, it is the only method of reproduction.

• The process involves the stages: Interphase, Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.

• Interphase: Daily cell functions, DNA replicates, and condenses.

• Prophase: Chromosomes condense, centrioles move to poles, nuclear membrane breaks down.

• Metaphase: Chromosomes align at the cell's equator, spindle fibers attach to centromeres.

• Anaphase: Chromosomes separate and are pulled to opposite poles, cell elongates.

• Telophase: Chromosomes decondense, new nuclear membranes form, cell begins to pinch.

• Cytokinesis: Cell completely divides into two new cells.

• Plant vs. Animal Cells: Plant cells form a cell plate between daughter cells that develops into new cell walls, while animal cells pinch.

• DNA Replication: Copying of DNA.

• Somatic Cells: Body cells (e.g., liver, skin, nerve, bone, blood).

• Cancer: Uncontrolled cell division.

• Homologous Chromosomes: Chromosome pairs with similar size, shape, and genes.

• Genes: Sections of DNA code for specific proteins.

Other Asexual Reproduction Methods

• Sporulation: Mold and fungi produce spores that develop into new organisms.
• Vegetative Propagation: Runners, corms, and bulbs reproduce through mitosis.
• Binary Fission: Bacterial reproduction, one cell splits into two.
• Budding: New organisms grow from the parent organism (e.g., hydra, sponges).

Meiosis

• Meiosis is a form of sexual reproduction, creating gametes (sex cells).
• The result is four genetically different haploid sex cells (sperm or egg).
• The purpose is to create genetic diversity and produce sex cells.
• The process involves interphase, two rounds of division (meiosis I and meiosis II).
• Meiosis I: Homologous chromosomes pair up, exchange genetic material (crossing over), then separate.
• Meiosis II: Sister chromatids separate, final division, resulting in four haploid cells.

Gametogenesis

• Spermatogenesis: Produces four sperm cells at a time.
• Oogenesis: Produces one egg cell and three polar bodies.
• Fertilization: The joining of sperm and egg to restore the diploid chromosome number.