Macromolecules Cheat Sheet: Carbohydrates, Lipids, Proteins & Nucleic Acids
By Sarah Jenkins, M.S.N. · Updated April 18, 2026
The four macromolecules that make up all living things are Carbohydrates (energy), Lipids (long-term energy and membranes), Proteins (enzymes and structure), and Nucleic Acids (DNA and RNA genetic storage).
Whether you are taking the ATI TEAS or the Elsevier HESI A2, biological macromolecules are going to appear on your exam. These organic molecules are the physical building blocks of the human body, and nursing schools expect you to know them cold.
Because this topic is universal across exams, this cheat sheet applies directly to both. (Need to know how this fits into the broader syllabus? Check out our Ultimate TEAS 7 Study Guide or our Ultimate HESI Study Guide).
Monomers vs. Polymers
Before breaking down the four categories, you need to understand two vocabulary words that pop up relentlessly on multiple-choice sections:
- Monomer: Think of this as a single LEGO brick. It is one basic building block.
- Polymer: Think of this as a complete LEGO house. It is a large molecule made by snapping many monomers together.
1. Carbohydrates (The Energy Source)
Carbohydrates are the body's primary and most rapid source of energy. They are made of Carbon, Hydrogen, and Oxygen.
Monomer: Monosaccharides (e.g., glucose, fructose).
Polymer: Polysaccharides (e.g., starch, glycogen, cellulose).
Cellular Function: Instant fuel for the body. Animals store excess carbohydrates in the liver and muscles as glycogen.
2. Lipids (Fats & Membranes)
Lipids are unique because they are hydrophobic (they repel water). This is crucial! Remember that oil and water don't mix.
Monomer: Fatty acids and glycerol (Note: lipids don't form true polymers like the other three).
Types: Triglycerides, phospholipids, and steroids.
Cellular Function: Long-term energy storage, insulation, and the creation of the cellular plasma membrane (phospholipid bilayer).
3. Proteins (The Workers)
Proteins do almost everything in the cell. They build muscle, act as messengers, transport oxygen, and speed up chemical reactions.
Monomer: Amino acids (There are 20 different ones).
Polymer: Polypeptide chains.
Cellular Function: Structure (keratin), transport (hemoglobin), and catalysis (enzymes).
📋 From the Tutor's Desk
Many of my TEAS students lose points on enzyme questions because they don't realize that enzymes are just proteins. An enzyme is a highly specialized protein folded into a specific "lock and key" shape to speed up chemical reactions. If a question asks what class of macromolecule an enzyme belongs to, the answer is always Proteins. Furthermore, if you see a word ending in "-ase" (like an amylase or lipase), it's definitely an enzyme!
4. Nucleic Acids (Genetic Blueprints)
Nucleic acids store the genetic information necessary to build proteins. They dictate your eye color, your blood type, and essentially who you are.
Monomer: Nucleotides (made of a sugar, a phosphate group, and a nitrogenous base).
Polymer: DNA and RNA.
Cellular Function: Storing and transmitting genetic information.
Test Your Knowledge
Don't just read the definitions. You need to apply them in a multiple-choice format. Select your exam below and take a free mock practice test:
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