USMLE ROADMAP BIOCHEMISTRY LANGE EBOOK PDF DOWNLOAD

USMLE ROADMAP BIOCHEMISTRY LANGE EBOOK PDF DOWNLOAD
USMLE ROADMAP BIOCHEMISTRY LANGE EBOOK PDF DOWNLOAD A. The special chemical properties of water make it ideal as the main physiologic sol- vent for polar substances in the body.
1. Within the water molecule, the oxygen nucleus draws electrons away from the
hydrogen atoms, producing an internal charge separation that makes each molecule magnetic or polar.
2. Substances that dissolve well in water are referred to as polar or hydrophilic.
3. Molecules that dissolve sparingly in water are nonpolar or hydrophobic.
B. Water molecules bind with each other through important noncovalent interac- tions called hydrogen bonds.
1. Hydrogen bonds result from attraction between the partially positively
charged hydrogen atoms of one molecule and the electronegative atom, usually
oxygen or nitrogen, of another molecule.
2. Hydrogen bonds are weak and rapidly break and re-form up to 1012 times per
second in water at 25Β°C.

C. The hydrogen bond network of water molecules confers special properties on water that are important for sustaining life.
1. Water has a high surface tension where it comes in contact with air.
a. Surface tension is the force acting to push together the liquid molecules at an air-liquid interface.

b. This property causes the liquid to form droplets and to resist passage of sub- stances across the interface.
c. The surface tension of fluid at the alveolar air-water interface of the lungs contributes to elastic recoil that causes the alveoli to return to the original volume after inflation during breathing.
2. Water has a high heat of vaporization, ie, the amount of heat needed to con- vert from liquid to gas phase. In conjunction with its high heat capacity, this property allows water to carry away heat efficiently as it evaporates, which ac- counts for the cooling effects of perspiration.

3. Water has a high dielectric constant, which is a measure of its ability to carry electrical current, as it does in nerve cells.

USMLE ROADMAP BIOCHEMISTRY LANGE EBOOK PDF DOWNLOAD