Summary of Key Concepts: Biological Molecules

Biological Macromolecules

Biological macromolecules are large, complex molecules essential for life. They are built from smaller units called monomers and perform a variety of functions in living organisms. The four major classes are carbohydrates, lipids, proteins, and nucleic acids.

Carbohydrates

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. They serve as a primary source of energy and provide structural support in plants.

• Function: Dietary energy; storage; plant structure

• Monomer: Monosaccharide (simple sugar, e.g., glucose)

• Examples: Glucose, fructose, disaccharides (lactose, sucrose), polysaccharides (starch, cellulose)

Definition: Monosaccharides are the simplest form of carbohydrates and can be joined to form more complex sugars.

Example: Starch is a polysaccharide used by plants for energy storage.

Lipids

Lipids are hydrophobic molecules that include fats, oils, and steroids. They are important for long-term energy storage and make up cell membranes.

• Function: Long-term energy storage; components of cell membranes; hormones (steroids)

• Monomer: Components of a fat molecule (glycerol and fatty acids)

• Examples: Fats, oils, steroids

Definition: Triglycerides are a common form of fat, consisting of one glycerol molecule bonded to three fatty acids.

Example: Steroids, such as cholesterol, function as hormones in the body.

Proteins

Proteins are polymers made of amino acids. They perform a wide range of functions, including catalyzing reactions, providing structure, and transporting molecules.

• Function: Enzymes, structure, storage, contraction, transport, etc.

• Monomer: Amino acid

• Examples: Lactase (an enzyme), hemoglobin

Definition: Amino acids are organic compounds that combine to form proteins. There are 20 different amino acids found in proteins.

Example: Hemoglobin is a protein in red blood cells that transports oxygen.

Nucleic Acids

Nucleic acids store and transmit genetic information. The two main types are DNA and RNA.

• Function: Information storage

• Monomer: Nucleotide

• Examples: DNA, RNA

Definition: Nucleotides are the building blocks of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogenous base.

Example: DNA stores genetic information in the sequence of its nucleotides.

Comparison Table: Biological Macromolecules

Biological Macromolecule	Function	Monomer	Examples
Carbohydrates	Dietary energy; storage; plant structure	Monosaccharide	Glucose, fructose, lactose, sucrose, starch, cellulose
Lipids	Long-term energy storage; components of cell membranes; hormones (steroids)	Components of a fat molecule (glycerol and fatty acids)	Fats, oils, steroids
Proteins	Enzymes, structure, storage, contraction, transport, etc.	Amino acid	Lactase, hemoglobin
Nucleic acids	Information storage	Nucleotide	DNA, RNA