Chemistry for Biology 

Carbon-based compounds are some of the most versatile organic compounds in living systems. It is incredible how Carbon can be arranged one way to produce stable graphite, yet it can also be arranged in another way to form diamond, one of the most unstable and virtually indestructible material on earth.

 

 

 

What are carbon-based compounds?

 

 

 

Carbon-based compounds usually refer to organic molecules that make life. Carbon-based compounds include hydrocarbons such as ethane, methane, and propane. It can also include the complex molecules that make up life such as carbohydrates, lipids, proteins, and nucleic acids. Since carbon has four electrons in its valence shell it can form covalent bonds with up to four other atoms. The polarity of the molecule would be determined by whether or not the electrons are shared equally. These molecules are arranged in a straight chain (linear, i.e. glycerol), a branched chain (i.e. hexane), and a ring structure (circular, i.e. vanillin). Carbon-based compounds can also be saturated (contains no carbon=carbon double bonds), or unsaturated (contains one or more carbon=carbon double bonds). The most important carbon-based compounds would be the biological molecules. Carbohydrates, lipids, proteins, and nucleic acids are all carbon-based. Life, then, is carbon based. Carbons make up the backbone of carbohydrates, the glycerols in lipids, the carboxly groups in protein, and the pentose sugar in DNA/RNA. Overall, there is an abundant number of carbon-based compounds and these compounds are what contributes to the diversity of life.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Functional Groups:

 

Carbons and hydrogens serve as the backbone for functional groups and help influence the property of these groups. Functional groups are groups of atoms that when bonded to the carbon skeleton, help influence the chemical properties and activity of molecules. Without carbon serving as a framework for these atoms to form covalent bonds with these functional groups would not exist. Let's look at the functional groups individually.

 

 

• Hydroxyl group (-OH)- This functional group is made of an oxygen and a hydrogen. Hydroxyl group molecules are often very polar and are easily soluble in water. The generic name for molecules with this group are alcohols. The sugar that you eat and the DNA that stores your genetic information contains this functional group.

 

 

 

• Carbonyl group (-C=O)- This functional group is made up of a carbon double bonded to an oxygen. This group is also polar and is frequently found in carbohydrates. The structure and placement of the carbonyl group is very important. If it is placed at the end of the molecule, then it is glucose. However, if it is located in the middle of the molecule then it is known as fructose. These carbonyl groups can combine with hydroxyl groups to form complex ring structures of carbohydrates.  

 

 

 

• Amino group (-NH2)- These functional groups are basic and accepts protons. They serve as an important component of the basic building blocks of proteins, amino acids. The carbon skeleton holds the amino group with a carboxyl group to make amino acids. The R group attached to the carbon usually determines the other properties of the amino acid.

 

 

 

• Carboxyl group (-COOH)- This functional group is extremly acidic due to its ability to release hydrogen ions and form COO. Carboxyl groups are found in every amino acid because it is one of the two main components that make up amino acids.

 

 

 

• Methyl group (-CH3)- One of the few non-polar functional groups. Methyl groups along with hydrocarbon chains can form long non-polar compounds that would be insoluble in water. Fatty acids, methane, nucleotides, wax, and many non-polar compounds are made up of methyl. The methyl group is what allows polar molecules to be non-polar and also allows certain functional molecules to be non-functional.

 

 

 

• Phosphate group (-O(PO3)2-)- These functional groups are very polar and is an important component of adenosine triphosphate, ATP. The phosphate group allows weak bonds to form due to it's unstable characteristics. This allows for the bonds between phosphates to be easily broken releasing high amounts of energy. Phosphate groups are also found in DNA/RNA and the 5' to 3' characteristics are due to phosphates attaching to either the 3-carbon or 5-carbon side of the pentose sugar. 

 

 

 

 

• Sulfhydryl group (-SH)- SUlfhydryl is a very reactive group. These functional groups can forn disulfide bridges to stabilze the structures of different biological molecules, i.e. proteins. Sulfhydryl groups are also very important in contributing to the functionality of enzymes. Sulfhydry is found in the active sites of enzymes that reacts to certain molecules to allow enzymes to function and speed up reactions.