During prophase I, each of the homologous pairs of chromosomes can be seen as bivalent or as a grouping of two chromosomes said to be sister chromatids. The site at which the crossing over occurs on the sister chromatids is known as the chiasma. Prophase I is the longest phase during the meiosis process and takes up to 90 percent of the total time of cell division.
Castor beans are pressed to extract castor oil which is used for medicinal purposes. Ricin (a toxic substance present in the plant) does not partition into the oil because it is water-soluble, therefore, castor oil does not contain ricin, provided that no cross-contamination occurred during its production.icin (a toxic substance present in the plant) does not partition into the oil because it is water-soluble, therefore, castor oil does not contain ricin, provided that no cross-contamination occurred during its production.
Castor beans, from which ricin is synthesized (Wikimedia Commons). Made from ordinary castor beans, ricin can be incredibly dangerous and even deadly -- if milled or processed right. The substance is called âvery toxicâ by the U.S. Centers for Disease Control and Prevention.icin is very difficult to process from the beans in which it is naturally found. It is a part of the waste âmashâ produced when castor oil is made, according to the CDC, and if the beans themselves are chewed and swallowed, the released ricin can cause injury.