Le biomolecole

La chimica organica studia i composti del carbonio detti composti organici;  tra questi vi sono le molecole biologiche o biomolecole, la materia prima che forma tutti gli organismi viventi. Le molecole biologiche possono essere suddivise in quattro classi di composti: glucidi, lipidi, protidi e acidi nucleici. Il ruolo centrale del carbonio Le molecole biologiche o biomolecole sono costituite da carbonio, idrogeno, azoto, ossigeno, fosforo e zolfo. Lo scheletro carbonioso Poiché un atomo di carbonio ha quattro elettroni nel suo livello energetico più esterno, esso tende a formare quattro legami covalenti con, al massimo, altri quattro atomi: il metano, che è … Continua a leggere Le biomolecole

Anglo-Saxon England ( A1 level)

In the 5th century Britain was invaded by the Germanic tribes of the Saxons, the Angles and the Jutes who used the runic alphabet. The Anglo-Saxons gave Britain its new name, England, which means the land of the Angles. Wales meant “ the land of the foreigners”. Other Celts were driven towards the North, to what is now Scotland. The Anglo-Saxons created an heptarchy, that is seven kingdoms; they were : East Anglia, Northumbria, Essex, Sussex and Wessex. Later they became just three kingdoms. The Anglo-Saxon society was characterized by the king and other important people who belonged to a … Continua a leggere Anglo-Saxon England ( A1 level)

The Norman Conquest

The Norman conquest marked the beginning of a new era. The Normans brought a new social system, known as the feudal system, based on a strict hierarchy that saw the king at the top, under him the barons, then the knights and finally the peasants and the serfs. The king gave the land to his barons in return for military service; the same relationship linked the knights to the barons. Twenty years after the conquest, William sent his men throughout England to make a survey of the economic life of the country: in 1086 the record, known as “Dornesday Book”, … Continua a leggere The Norman Conquest