Beauty

Explain what is meant by the term endocrine gland.

Describe the cellular structure of an islet of Langerhans from the pancreas.

Outline the role of the pancreas as an endocrine gland.Exocrine Gland: a gland that secretes externally through a ductEndocrine Gland: a gland that secretes hormones into the bloodstream.

CARBON CHEMISTRY AND FUNCTIONAL GROUPS

* carbon has the capability to bond with four other atoms

* when carbon is bonded to four atoms, it is "saturated" and it forms a symmetrical molecule with a tetrahedral shape

* if the four atoms are the same, the structure is non-polar, since the pull on the shared electron pairs is evenly distributed throughout the molecule, resulting in no over all net pull

* molecules that contain only carbon and hydrogen atoms are called hydrocarbons

* Figure 2, p. 25 shows the ball and stick, and space-filling model of hydrocarbon pentane

* all hydrocarbons are symmetrical molecules, and are therefore non-polar

* sometimes, oxygen, sulfur, phosphorous, as well as many other atoms, can attach to the carbon backbone of a hydrocarbon to form clusters of atoms called functional groups - these are special arrangements of atoms that exist in molecules and give them their character

* Table 1, p. 25, lists the more common functional groups found in biology

* various atoms always form the same number of covalent bonds with adjacent atoms