Monomers polymers and monosaccharides

• Monomer

  Smaller unit from which larger molecules are made
• Polymer

  Molecules made from large number of monomers joined
• Examples of monomers

  Monosaccharides

  Amino acids

  Nucleotides
• What is a condensation reaction?

  -A reaction that joins two molecules together

  • with the formation of a chemical bond

  • and involves the elimination of a molecule of water.
• What is a hydrolysis reaction?

  • A reaction that separates molecules

  • by breaking a chemical bond

  • and involves the use of a water molecule.
• Monosaccharide

  Monomers from which larger carbohydrates are made
• Three common monosaccharides

  Glucose

  Galactose

  Fructose
• Two isomers of glucose

  alpha glucose and beta glucose
• Alpha glucose

  hydrogen at top, OH at bottom
• Beta glucose

  glucose where on C1 OH on top, H on bottom
• Describe how disaccharides are formed

  By a condensation reaction between two monosaccharides
• Glucose + glucose

  maltose + water
• glucose+fructose

  Sucrose +water
• glucose +galactose

  lactose + water
• Describe test for reducing sugar

  1.Add Benedict's reagent

  2. Heat

  3.A positive results is a colour change from blue to green/yellow/orange/red
• Suggest why the colour change occurs at the top of the test tube first:

  Heat rises (convection currents).

  The the reaction occurs at the top of the test tube first
• Describe the test for a non-reducing sugar (4 marks):

  1 Following a negative reducing sugars test

  2. Boilthe sample in acid (acid hydrolysis). Then add alkaline to neutralise.

  3. Add Benedict's reagent and heat

  4. A positive result will go from blue to orange/red
• Describe the test for starch (2 mark):

  1. Add iodine to the sample

  2.A positive result will go from orange to blue/black
• Describe the test for lipids (3 marks):

  1 Add ethanol and shake to dissolve

  2. Then add distilled water

  3. A positive result is a white emulsion
• Describe the test for proteins (2 marks):

  1.Add biuret to the sample

  2.A positive result will go from blue to purple
• Name two groups of lipids

  1.Triglycerides

  2. Phospholipids
• Name the reaction that forms lipids:

  condensation
• Condensation reactions join the molecules to create triglyceride. Name the bond that forms and state between which molecules of the lipid it forms:

  • Bond - Ester bond

  • Location - Between glycerol and a fatty acid (RCOOH)
• saturated fatty acid

  The hydrocarbon chain only contains single carbon bonds
• Unsaturated fatty acids

  The hydrocarbon chain contains at least one double bond between carbon atoms.
• Describe the difference between the structure of a phospholipid and triglyceride molecule. (1 mark)

  In phospholipids, one of the fatty acids of a triglyceride is substituted by a phosphate-containing group.
• Name the reaction that joins the two fatty acids to the glycerol molecule and what bond is formed.

  Reaction -Condensation

  • Bond- Ester bond
• Phospholipids

  The 'head' of a phospholipid is described as being hydrophilic. It attracts water as it is charged. Due to the phosphate group being charged, it repels other fats.

  The fatty acid chain is not charged. It is known as the hydrophobic 'tail' and it repels water but will mix with lipids
• amino acids


  monomers which make up proteins.

  -there are 20 different amino acids
• There are 20 different amino acids. Which part of the amino acid general structure differs in all 20?

  The r group
• Name the reaction that joins amino acids together to form a polypeptide chain and the bond that forms:


  • Reaction - Condesation

  • Bond - Peptide bond
• Protein-primary structure

  The sequence/order of amino acids in a polypeptide chain
• secondary structure of protein

  The folding of the primary structure into an alpha helix or beta pleated sheet, held in place by hydrogen bonds.
• tertiary structure of protein

  The further folder of the secondary structure to create a unique 3D shape, held in place by hydrogen, ionic and sometimes disulfide bonds.
• quaternary structure of a protein

  There is more than 1 polypeptide chain in the protein.