3A_Biomolecules

=Biomolecules =

** Statements and Supporting Examples (reference to RaM Bio Site) **
Energy is stored in the organization of matter.
 * Statement:**

Fats are energy storage molecules. When the body needs energy, fats are broken down into glucose.
 * Example:**

**High heat capacity **  The temperature of liquid water rises and falls more slowly than that of most other liquids because the hydrogen bonds between water molecules hold more heat. This protects organisms from rapid temperature changes and helps them maintain homeostatic temperature. **High heat of vaporization **  Hydrogen bonds between water molecules require a relatively large amount of heat to break. This property moderates Earth’s surface temperature; permitting living systems to exist. When animals sweat, evaporation of the sweat removes body heat, thus cooling the animal.  **Water is a solvent **  Water dissolves a great number of substances (e.g., salts, large polar molecules). Ionized or polar molecules that are attracted to water are **hydrophilic ** (“water loving”); whereas non-ionized and nonpolar molecules that cannot attract water are **hydrophobic ** (“water fearing”). A solution contains dissolved substances called ** solutes. ** Cohesion ** allows water to flow freely without molecules separating. Adhesion is ability to adhere to polar surfaces. These characteristics allow water to rise up a tree from the roots to the leaves through small tubes. Adhesion of water to walls of vessels prevents water columns from breaking apart. Cohesion allows evaporation from leaves to pull water columns from roots. **Water has a high surface tension ** Water is relatively difficult to break through at its surface. This property permits a rock to be skipped across a pond surface and supports insects walking on the surface of water. **<span style="background-color: #d5a1fc; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 110%; letter-spacing: 0px; text-align: center;">Ice is less dense than water ** <span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%; letter-spacing: 0px;"> Below 4° C, hydrogen bonding becomes more rigid but more open, causing expansion. Because ice is less dense, it floats; therefore, bodies of water freeze from the top down. If ice was heavier than water, ice would sink and bodies of water would freeze solid. This property allows ice to act as an insulator on bodies of water, thereby protecting aquatic organisms during the winter.
 * <span style="background-color: #d5a1fc; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 110%; letter-spacing: 0px; text-align: center;">Cohesion and adhesion ****<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%; font-weight: normal; letter-spacing: 0px;">

<span style="font-family: Arial,Helvetica,sans-serif;"> Source: http://glencoe.mcgraw-hill.com/sites/dl/free/0035456775/694192/bioTP_CH2_mgb_final_OK.pdf

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The two most important characteristics of carbon as a basis for the chemistry of life, are that it has four valence bonds and that the energy required to make or break a bond is just at an appropriate level for building molecules which are not only stable, but also reactive. The fact that carbon atoms bond readily to other carbon atoms allows for the building of arbitrarily long and complex molecules. ====== <span style="color: #ff6d1f; font-family: Arial,Helvetica,sans-serif; font-size: 105%;"> <span style="font-family: Arial,helvetica,sans-serif;">There are not many other elements which appear to be even promising candidates for supporting life-like behaviour, but the most frequent alternative suggested is silicon. This is in the same group in the Periodic Table of elements and therefore also has four valence bonds. It also bonds to itself, but generally in the form of crystal lattices, less amenable to a complete source of life, rather than long chains. However, its compounds are generally highly stable and do not support the ability to readily re-combine in different permutations in a manner that would plausibly support life-like processes.
 * Additional Information -**

Source: http://en.wikipedia.org/wiki/Carbon-based_life

<span style="color: #ac066d; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">**Comparison Table**
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