Monomers and polymers
Laura Armstrong
Teacher
Recall Questions
This topic requires prior knowledge from GCSE Biological Molecules. Feel free to test your knowledge with these recall questions.
What is a polymer?
A polymer is a large molecule made up of many, repeating monomer units joined together by covalent bonds.
What are the repeating subunits of carbohydrates?
Sugars/ monosaccharides (glucose)
What are the repeating subunits of proteins?
Amino acids
Topic Explainer Video
Check out this @LauraDoesBiology video that explains monomers and polymers, or read the full notes below. Once you've gone through the whole note, try out the practice questions!
Monomers and Polymers
- Monomers are small, basic molecular units.
- Polymers are large molecules composed of many, repeating monomer units.
- Examples:
-
- Carbohydrates → Monosaccharides (e.g., glucose) form polysaccharides (e.g., starch, glycogen, cellulose).
- Proteins → Amino acids join to form polypeptides and proteins.
- Nucleic acids → Nucleotides form DNA and RNA.
Condensation and Hydrolysis Reactions
Condensation Reactions
- Condensation reactions occur when monomers bond together to form a polymer.
- A molecule of water (H₂O) is produced during the formation of each bond.
- Examples:
- Formation of glycosidic bonds in carbohydrates.
- Formation of peptide bonds in proteins.
- Formation of phosphodiester bonds in nucleic acids.
Hydrolysis Reactions
- Hydrolysis reactions break polymers into their monomers by adding water to break the bonds.
- Examples:
- Breaking starch into maltose using amylase (glycosidic bond hydrolysis).
- Breaking proteins into amino acids using proteases (peptide bond hydrolysis).
- Removing fatty acids from glycerol in triglycerides using lipases (ester bond hydrolysis).
Key Terms
- Monomer: A small unit that can form larger molecules.
- Polymer: A large molecule made of repeating monomer units.
- Condensation reaction: A reaction where monomers join and water is released.
- Hydrolysis reaction: A reaction where polymers break down with the addition of water.
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Exam Tips
- Always specify the type of bond broken or formed in your answers (e.g., peptide, glycosidic, phosphodiester).
- Don’t forget that water is produced in condensation reactions or added in hydrolysis reactions.
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Explain how biological polymers are formed and broken down. (2 marks)
Biological polymers are formed by condensation reactions, where many monomers join together, forming covalent bonds and producing water.
Conversely, biological polymers are broken down by hydrolysis reactions, where water is added to break the covalent bonds between monomers.
Practice Question
Try to answer the practice question from the TikTok on your own, then watch the video to see how well you did!