Overview
This lesson covers macromolecules, their building blocks (monomers and polymers), and explains the four main types: carbohydrates, lipids, proteins, and nucleic acids.
Macromolecules: General Concepts
- Macromolecules are large molecules essential to all living organisms.
- They are made of small units called monomers, which join together to form chains called polymers.
- The four main types of macromolecules are: carbohydrates, lipids, proteins, and nucleic acids.
Carbohydrates
- Carbohydrates are the main energy source for most living things and provide structure for many plants.
- Their monomers are called monosaccharides, which are simple sugars like glucose, fructose, and ribose.
- Chains of monosaccharides are called polysaccharides.
- Examples of polysaccharides:
- Starch (energy storage in plants)
- Glycogen (energy storage in animals)
- Cellulose (structure in plants)
- Chitin (structure in insects)
Lipids
- Lipids include fats, phospholipids, and steroids, and are all hydrophobic.
- Functions include energy storage, forming cell membranes, and acting as hormones.
- Lipids do not have true monomers, but include:
- Triglycerides (fats)
- Saturated and unsaturated fats
- Phospholipids (form cell membranes)
- Steroids (such as cholesterol and sex hormones)
Proteins
- Proteins are involved in nearly all cellular functions and are major components of living organisms.
- Their monomers are amino acids, with 20 different types.
- Chains of amino acids are called polypeptides.
- The function of a protein depends on how it folds.
Nucleic Acids
- Nucleic acids store, transmit, and express genetic information.
- Their monomers are nucleotides (such as adenine, guanine, and thymine).
- Chains of nucleotides are called polynucleotides, which make up DNA and RNA.
Key Terms & Definitions
- Macromolecule — a large molecule made of smaller units (monomers).
- Monomer — a small building block that can join with others to form a chain.
- Polymer — a chain of monomers.
- Monosaccharide — a single sugar molecule, building block of carbohydrates.
- Polysaccharide — a chain of many monosaccharides.
- Amino acid — building block of proteins.
- Polypeptide — a chain of amino acids that forms proteins.
- Nucleotide — building block of nucleic acids.
- Polynucleotide — a chain of nucleotides (e.g., DNA, RNA).
Actions / Next Steps
- Watch the suggested video about DNA and RNA for more information.
- Look for videos on each type of macromolecule as they become available.