General Reproduction Overview

General Reproduction

• Reproduction is the process of producing offspring, creating copies of organisms and ensuring the continued existence of species.
• Reproduction can be categorized into two main types: asexual and sexual.
• Asexual reproduction involves a single parent and produces genetically identical offspring.
• Sexual reproduction involves two parents and produces genetically diverse offspring.

Asexual Reproduction

• This type of reproduction is common in unicellular organisms and some multicellular organisms.
• Common methods include:
  • Binary fission: A single parent cell divides into two identical daughter cells, common in bacteria.
  • Budding: A new organism develops from an outgrowth or bud of the parent organism, common in yeast.
  • Spore formation: A parent organism creates spores which develop into new individuals, common in fungi and some plants.
  • Vegetative reproduction: Offspring develop from vegetative parts of the parent plant, such as roots, stems or leaves. Examples include bulbs, corms, tubers, runners and rhizomes commonly seen in plants.
    • Cutting: A piece of a plant is cut off and planted to develop a new plant
    • Layering: A stem of a plant is bent and covered with soil to encourage new roots and eventually develop a new plant.
    • Grafting: The stem of one plant is attached to another to create a combination plant
  • Regeneration: The ability of an organism to grow back lost body parts. Examples include starfish, earthworms, hydra and planarian.

Mitosis

• Mitosis is a type of cell division where a single cell divides into two identical daughter cells.
• It's crucial for growth, repair, and asexual reproduction in eukaryotic organisms.
• Divided into five main phases: Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
• Key aspects of Mitosis include the duplication of DNA and the equal distribution of duplicated chromosomes into the two daughter cells.

Meiosis

• Meiosis is a specialized type of cell division that reduces the chromosome number by half, creating gametes (sex cells).
• It involves two rounds of division (Meiosis I and Meiosis II).
• Meiosis I: Homologous chromosomes pair up, crossing over occurs, and the chromosome number is reduced to half.
• Meiosis II: Sister chromatids separate, and four haploid daughter cells are produced.
• Key differences between Mitosis and Meiosis : Mitosis produces two diploid cells, Meiosis produces four haploid cells, Mitosis produces genetically identical cells, Meiosis produces genetically unique cells.

Nondisjunction

• Errors in meiosis can lead to nondisjunction, where chromosomes fail to separate. Different types of nondisjunction are possible in Meiosis 1 or 2.
• This can lead to abnormalities in the resulting gametes and offspring.

Cells

• All living organisms are composed of one or more cells.
• Cells divide to ensure growth, repair, and reproduction of organisms.
• A cell's cytoplasm contains important chemical components that are not resynthesized from DNA every time a cell divides.
• Cells of higher organisms contain complex structures that must be duplicated during cell division.