General Reproduction Overview

Study Notes

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.

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 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 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.

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.

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.