Class II MHC glycoproteins expressed predominantly on pAPCs, where they primarily present exogenous antigenic peptides to CD4+ T cells.

TLS Online TPP Program

#Id: 7761

#Section 2: General Biology

A covalent bond is a chemical bond that occurs when two or more atoms share electrons. The sharing of electrons helps complete the outer shell, or valence shell, of both atoms. The sharing of electrons creates a stable balance of attractive and repulsive forces between atoms.

TLS Online TPP Program

#Id: 7760

#Section 2: General Biology

Sulfur normally exists as an eight-atom molecule, S8, while phosphorus exists as a four-atom molecule, P4

TLS Online TPP Program

#Id: 7759

#Section 2: General Biology

Some elements exist naturally as molecules. For example, hydrogen and oxygen exist as two-atom molecules.

TLS Online TPP Program

#Id: 7758

#Section 2: General Biology

A molecule is the smallest part of a substance that has the physical and chemical properties of that substance. In some respects, a molecule is similar to an atom. A molecule, however, is composed of more than one atom.

TLS Online TPP Program

#Id: 7757

#Section 2: General Biology

Molecules are groups of atoms that behave as a single unit.

TLS Online TPP Program

#Id: 7756

#Section 2: General Biology

Fluorine (the most electronegative element) is assigned a value of 4.0, and values range down to cesium and francium which are the least electronegative at 0.7