This document contains lecture notes from Lesson 1: Intro to Biomolecules to Lesson 8: Translation , including all the learning objectives/ spec points. This includes some detailed explanations of concepts lecturers explained live during their lectures that are not explained on the actual slides th...
S1,T1: 4BBY1013: Biochemistry Notes
15 December 2024 21:33
L1: The Molecules of Life
a) Recognise that complex biological macromolecules are made of smaller biomolecules
- Monomers might also have distinct functions
○ Sugars, fatty acids: energy source
○ Nucleotides (ATP): energy carrier
b) Outline the chemical features and properties of the four main classes of biological molecules
Carbohydrates
- Monosaccharides (simple sugars) are the single molecules which make up carbohydrates
- Functional groups include carbonyl and hydroxyl groups
- Hydrophilic
- polar due to the presence of the oxygen atoms present in hydroxyl and carbonyl groups
- Water soluble since hydrogen bonds can be formed with the oxygen atoms and water molecules
- Glucose, Fructose , ribose
c) Distinguish aldoses and ketoses and explain the formation of ring structures
- Aldoses are monosaccharides with aldehyde groups present
○ Glucose (6C) , ribose (5C) , glyceraldehyde (3C)
- Ketoses are monosaccharides with ketone groups present
○ Fructose (6C) , ribulose (5C) , dihydroxyacetone (3C)
- However, 5 and 6 carbon molecules spontaneously form ring structures in aqueous solutions
- 1:40000 glucose molecules are linear in solution
- The carbonyl group reacts with a hydroxyl group
d) Distinguish isomeric forms of glucose: enantiomers, anomers, epimers
- Enantiomers: non superimposable mirror images / optical isomers
○ D and L glucose
○ They differ in their configuration of the -OH group at the C1 atom in the linear form. In D glucose the -OH group is on the right hand side, whilst in L glucose it is on the left
○ D glucose is the most naturally occurring
○ In fact, only D glucose can be metabolised in the glycolysis pathway
Notes Page 1
, - Anomers: pair of enantiomers that are almost identical except at the anomeric carbon which bears the carbonyl group in the sugar's open chain form (anomeric carbon)
○ Includes alpha and beta D- glucose
○ When glucose is in the ring structure the hydroxyl can be attached at either position on carbon 1
○ Alpha and beta forms interconvert rapidly in solution
○ In our bodies, once glucose forms bonds , the monomers making up this polymer can only be alpha glucose
○ This is because the body does not have the enzymes to break down beta glucose
- Epimers: difference in the location of an -OH group in one location
○ Examples include the diagram shown below as well as alpha and beta D-glucose
e) Recognise and correctly name alpha and beta glycosidic bonds in disaccharides and polysaccharides
- Complex carbohydrates are formed when glycosidic bonds form between monosaccharides
- When the bond is formed, the alpha or beta configuration is locked
Once it's an alpha glucose, it remains an alpha glucose and same for beta glucose
Alpha glycosidic linkages are below and beta glycosidic linkages are above
Notes Page 2
, Polysaccharides can act as energy stores:
- Starch ( amylose and amylopectin) in plants
○ Amylose has a lot of alpha 1,4 linkages making it quite linear
- Glycogen in animals
○ Glycogen has a similar structure to amylopectin , being more branched due to alpha 1,6 glycosidic bonds
Complex oligosaccharides (a few saccharides) can form recognition molecules like glycoproteins and glycolipids (i.e. blood group determinants)
Lipids
- Water insoluble
- Soluble in organic solvents like ethanol OMSO
- Include the triacylglycerols, glycerophospholipids and steroids+ cholesterol
- Made up of fatty acid monomers
○ Hydrophilic -COOH head
○ Hydrophobic hydrocarbon tail prevents forming hydrogen bonds with water molecules
- Saturated fatty acids are straight chains with no C=C bonds meaning that they have a higher melting point and stay solid at room temperature
- Unsaturated fatty acids form kinks in their chains due to C=C bonds . This decreases the melting point so they are more likely to be liquid at room temperature.
- The double bonds also restrict rotation about the bond
- The length of fatty acid tails also determines physical properties
Notes Page 3
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