Organic Molecules Unit 3 Lesson 1

CARBON Organic means that something contains carbon. In Biology, ‘organic’ especially refers to carbon-containing compounds or substances that are part of the processes of living organisms. The chemistry of carbon allows for the formation of an enormous variety of organic molecules. Since carbon has 4 outer shell electrons, it can form 4 chemical bonds with other atoms or molecules at a time.

CARBON-HYDROGEN BONDS Organic molecules contain carbon atoms that are bonded to hydrogen atoms. Carbon-hydrogen bonds are a vital part of the structure and function of living things. Example: Methane (CH4) is the byproduct of methanogenesis (microbial metabolism). In contrast, inorganic molecules do not contain carbon-hydrogen bonds. Methane (CH4)

CARBON-CARBON BONDS Carbon usually bonds with hydrogen, oxygen, nitrogen, or another carbon. When two carbon atoms bond, they either share 1 pair of electrons in a single bond, 2 pairs of electrons in a double bond, or 3 pairs of electrons in a triple bond. Example: The two carbon atoms in acetylene, a gas commonly used as fuel, share 3 pairs of electrons in a triple bond. Acetylene

FUNCTIONAL GROUPS Functional groups are specific clusters of atoms within molecules that are responsible for the way molecules behave. The structure of a functional group determines its function. Example: Ester functional groups are responsible for the characteristic chemical reactions of ester molecules. Ester molecules are commonly found in fragrances and essential oils. Ester Functional Group

HYDROPHILIC COMPOUNDS Functional groups are either polar or nonpolar. Polar molecules are hydrophilic (water loving). Hydrophilic compounds can be dissolved by water because they attract water. Example: Salt (NaCl) is able to dissolve in water because it is hydrophilic.

HYDROPHOBIC COMPOUNDS Nonpolar molecules are hydrophobic (water hating). Hydrophobic compounds cannot be dissolved by water because they repel water. Example: Plant cuticles consist of lipid and hydrocarbon polymers saturated with wax. The hydrophobic composition of a plant’s cuticle prevents moisture loss and excessive surface wetting.

ISOMERS Fructose Glucose Isomers are molecules that have identical molecular formulas but different structural arrangements. Example: Fructose and glucose have different structural arrangements but share the same molecular formula (C6H12O6).

MONOMERS AND POLYMERS Macromolecules are large molecules made up of hundreds or thousands of atoms. Polymers are large macromolecules that are composed of subunits known as monomers. Example: Amino acids (monomers) link together to make proteins (polymers).

CONDENSATION A condensation reaction occurs when smaller molecules (monomers) come together to form a macromolecule (polymer) and involves a loss of water. Condensation involves the formation of a chemical bond. Condensation Reaction Monomers coming together to form a polymer and give off water as a byproduct.

A polymer breaking down into monomers by the addition of water. HYDROLYSIS A hydrolysis reaction occurs when a macromolecule (polymer) breaks down into smaller molecules (monomers) and involves the addition of water. Hydrolysis involves the breakdown of a chemical bond. Hydrolysis Reaction A polymer breaking down into monomers by the addition of water.