Topic 1.1 + 1.2 carbs + lipids

• Monosaccharides are organic monomers that cannot be hydrolysed to a simpler sugar.
• The molecular formula of glucose is C6H12O6.
• The tails of phospholipids can splay outwards, providing waterproofing.
• Phospholipids form a phospholipid bilayer in water, making them a component of membranes.
• The structure of α-glucose is cis isomer.
• The structure of β-glucose is trans isomer.
• The functions of glucose are related to its structure, for example, it is small and water soluble, has a complementary shape to antiport for co-transport for absorption in gut, and has a complementary shape to enzymes for glycolysis, making it a respiratory substrate.
• Ribose is a pentose monosaccharide.
• In a condensation reaction, a chemical bond forms between two molecules and a molecule of water is produced.
• In a hydrolysis reaction, a water molecule is used to break a chemical bond between two molecules.
• A polysaccharide is a polymer made from a repeating monosaccharide unit, examples include starch, glycogen, and cellulose.
• Multiple monomers form many chemical bonds, resulting in a polysaccharide.
• A bond forms when monosaccharides react, either 1,4 or 1,6 glycosidic bond.
• Glycogen is the main storage polymer of α-glucose in animal cells, it is insoluble, does not diffuse out of cells, and is compact.
• Two monomers form one chemical bond, resulting in a disaccharide.
• Three disaccharides are maltose, sucrose, and lactose, all with molecular formula C12H22O11.
• Starch is a storage polymer of α-glucose in plant cells, it is insoluble and does not diffuse out of cells.
• Cellulose is a polysaccharide found in plant cells, it is insoluble, does not diffuse out of cells, and has a complex structure.
• Cellulose has 1,4 glycosidic bonds, is a straight-chain, unbranched molecule, and its alternate glucose molecules are rotated 180°.
• H-bond crosslinks between parallel strands form microfibrils, giving cellulose high tensile strength.
• Cellulose, a polymer of 𝛽-glucose, gives rigidity to plant cell walls, preventing bursting under turgor pressure and holding the stem up.
• Phospholipids are amphipathic, with a glycerol backbone attached to two hydrophobic fatty acid tails and one hydrophilic polar phosphate head.
• Saturated fats contain only single bonds, are straight-chain molecules with many contact points, have a higher melting point, and are found in animal fats.
• The structure of triglycerides relates to their functions, including high energy:mass ratio, insoluble hydrocarbon chain, slow conductor of heat, and less dense than water.
• Triglycerides form through a condensation reaction between one molecule of glycerol and three fatty acids, forming ester bonds.
• Unsaturated fats contain C=C double bonds, are 'kinked' molecules with fewer contact points, have a lower melting point, and are found in plant oils.