Cleavage

Cleavage refers to the process of splitting or dividing a substance into smaller parts. The term is used in various scientific and technical fields, each with its specific context and implications.

Biology

In biology, cleavage is the series of rapid cell divisions that occur immediately after the fertilization of an ovum. This process transforms the single-celled zygote into a multicellular structure known as a blastula. Cleavage is characterized by the absence of cell growth between divisions, resulting in progressively smaller cells called blastomeres.

Types of Cleavage

Cleavage patterns can vary significantly among different species. The main types include:

• Holoblastic Cleavage: Complete division of the egg into blastomeres, typical in species with little yolk, such as mammals and amphibians.
• Meroblastic Cleavage: Incomplete division of the egg, common in species with a large amount of yolk, such as birds and reptiles.

Stages of Cleavage

The stages of cleavage include:

• Zygote: The fertilized egg cell.
• Morula: A solid ball of blastomeres resulting from early cleavage divisions.
• Blastula: A hollow sphere of cells formed after the morula stage.

Geology

In geology, cleavage refers to the tendency of minerals to break along flat planes of weakness within their crystal structure. This property is a critical factor in identifying and classifying minerals.

Types of Cleavage

• Basal Cleavage: Cleavage parallel to the base of a crystal.
• Cubic Cleavage: Cleavage that occurs along planes parallel to the faces of a cube.
• Octahedral Cleavage: Cleavage along planes parallel to the faces of an octahedron.

Chemistry

In chemistry, cleavage describes the breaking of a chemical bond in a molecule, resulting in smaller molecules or atoms. This process can occur through various mechanisms, including:

• Homolytic Cleavage: The bond breaks evenly, with each fragment retaining one of the shared electrons.
• Heterolytic Cleavage: The bond breaks unevenly, with one fragment retaining both of the shared electrons.

Related Pages

• Cell division
• Fertilization
• Mineral
• Crystal structure
• Chemical bond