For example, when an oxygen atom binds to one of hemoglobin's four binding sites, the affinity to oxygen of the three remaining available binding sites increases; i.e. oxygen is more likely to bind to a hemoglobin bound to one oxygen than to an unbound hemoglobin.
Many medicines such as digitalis and quinine come from plant products. Drugs derived from plants have been in use to treat illnesses and various medical conditions for thousands of years. Digitalis, which is used to treat heart diseases was derived from foxglove plant while quinine which is use for treatment of malaria was derived from the bark of a peruvian tree, the Cinchona.
Homologues are chromosome pairs of the same length, centromere position, and staining pattern with genes for the same characteristics at corresponding locations. One homologous chromosome is inherited from the organism's mother, the other from the organism's father during sexual reproduction. The crossing over, or synapse, occurs during meiosis, which is the process of gamete formation.
