All 4 major types of biomolecules (macromolecules of life) are carbon based.

Carbon atoms can attach to each other and form straight or branched chains and ringed structures. These structures act as the backbones of different types of biological molecules.

However, some carbon containing compounds such as carbides, carbonates, simple oxides of carbon (CO2), allotropes of carbon and cyanides are considered to be inorganic.

  • A carbide consists of carbon and a less electronegative element. Examples - calcium carbide(CaC2), silicon carbide (SiC), tungsten carbide (WC), and cementite (Fe3C),each used in key industrial applications.
  • A carbonate is a salt of carbonic acid (H2CO3). The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group (R-OCOO-R).
  • A cyanide is any compound that contains monovalent combining group CN (cyano group).

major types of  biomolecules include:

  1. Carbohydrates (monosaccharides, oligosaccharides, polysaccharides)
  2. Lipids (triglycerides, phospholipids, steroids)
  3. Proteins
  4. Nucleic Acids (DNA, RNA)

Carbohydrates and lipids store energy needed to drive synthesis reactions.

Nucleic acids store and transfer genetic information that manages which macromolecules to synthesize.

Protein and nucleic acid enzymes catalyze biochemical reactions in both catabolism and anabolism of macromolecules.

Catabolism - the breakdown of biomolecules in living organisms.

Anabolism - the synthesis of complex biological macromolecules.

Isomers of life macromolecules

Isomers of biological molecules - compounds with the same molecular formula but different structures.

Structural isomers of macromolecules differ in the placement of their covalent bonds.

Stereoisomers - have similar placements of their covalent bonds but differ in how these bonds are made to the surrounding atoms.

Isomerism of carbon based biological molecules

Functional groups of four types of biomolecules: carbohydrates, lipids, proteins, and nucleic acids

Functional groups of different types of biomolecules: carbs, lipids, proteins and nucleic acidsFunctional groups of different types of biomolecules are specific groups (moieties) of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules.

Each functional group of biomolecule has a specific role in cell metabolism.

Hydroxyl group is the functional group of alcohols. It adds polarity to organic molecules. One example of alcohols is glycerol, also commonly known as glycerine. Glycerol is a polyalcohol and an important part of triglycerides and phospholipids.

Carbonyl groups of aldehydes and ketones generally also increase polarity and reactivity of biological molecules. Biomolecules containing carbonyls tend to be volatile and stimulate senses with both pleasant and unpleasant odors.

A carboxyl group of carboxylic acids contains both a carbonyl group and a hydroxyl group, bonded to the same carbon atom. Organic molecules containing carboxyl groups are often highly polar and reactive. Common biomolecules, containing the carboxyl functional groups, are fatty acids and amino acids.

Amino groups also increase polarity and reactivity of an organic molecule. They readily form hydrogen bonds with other polar molecules and water. Amines are weakly basic. Amino and carboxyl groups of amino acids react to each other to form peptide bonds of proteins.

Phosphate groups are highly acidic and reactive. Phosphates are essential to the metabolic processes of photosynthesis and cellular respiration. A transfer of a phosphate group from one molecule to another delivers energy to chemical reactions.

The sulfhydryl (–SH) group is essential to protein stabilization.  

Amino acids with –SH groups form bonds called disulfide bridges (S–S bonds) that help protein molecules to take on and maintain a specific shape.

Monomers and polymers of 4 types of biomolecules

Most biological macromolecules are made from single subunits, or building blocks, called monomers.

The monomers combine with each other using covalent bonds to form larger macromolecules known as polymers.

Polymers can be divided into two groups:

  1. natural polymers (different types of biomolecules),
  2. synthetic polymers.

Polymers are broken down into monomers in a process known as hydrolysis, which means “to split water,” a reaction in which a water molecule is used during the breakdown.

Dehydration reactions involve the formation of new bonds, requiring energy, while hydrolysis reactions break bonds and release energy.

Dehydration and hydrolysis reactions are catalyzed, or “sped up,” by specific enzymes made up of proteins.

4 types of biomolecules (natural polymers) are formed

from smaller building blocks called monomers.

 Natural PolymerMonomer 
Carbohydrates → Monosaccharides
Proteins → Amino acids
Nucleic acids (DNA, RNA) → Nucleotides

Lipids →