Nucleation is the process that enables the formation of crystals. Crystals may arise from solutions, liquids or vapors but must undergo the process of nucleation to do so. Essentially, nucleation is to crystals what metamorphosis is to insects.
Nucleation begins with the line up and arrangement of crystal particles. These particles include ions, atoms and molecules, which are established in patterns to enable the conversion to solids. Processes of nucleation may be homogenous or heterogeneous in nature. Heterogeneous nucleation involves the surface of a substance, such as a particle of dust or container wall, which acts as the central location for the orientation of atoms, molecules or ions. The process of homogenous nucleation is much less formal. During this transition, several particles move into their correct positions through random movements. Of the two, heterogeneous nucleation is more common. However, homogenous nucleation is necessitated when the extent of super saturation or super cooling increases. The substances created by nucleation vary widely in color, shape and physical structure. Some may crystallize under stable and predictable conditions, while others undergo transformations in chaotic and volatile environments. Glycerol is one end product of nucleation; this component, like others formed in stable conditions, is prone to super cooling.Learn More
Mitosis and cytokinesis differ in that mitosis the process in which a duplicated genome within a cell separates into identical halves, while cytokinesis involves the division of cellular cytoplasm into two daughter cells. Although both processes produce offspring cells, the cells produced during mitosis are identical, while those produced by cytokinesis are not. These processes also vary in length and complexity: mitosis occurs in three distinct phases, while cytokinesis requires just two.Full Answer >
In plant cells, chloroplasts perform photosynthesis, a process that converts light energy from the sun into chemical energy in the form of glucose. Plants can later use this stored chemical energy to carry out activities integral to life, such as growth and reproduction.Full Answer >
Tetrads, also known as bivalents, form during the prophase 1 stage of meiosis when duplicated chromosomes, each composed of two identical chromatids, pair up and complete the process of crossing over in which one chromosome exchanges corresponding segments of genetic material with the other chromosome in the tetrad. This exchange of physical parts and genetic information creates a tight grouping of the two chromosomes, each consisting of two sister chromatids.Full Answer >
"Crossing over" in meiosis refers to the process by which segments of DNA on nonsister, or homologous, chromatids break off and recombine on the other homologous chromatid. This process becomes a source of variation in egg and sperm cells.Full Answer >